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Study Objective: Hypoxemia is the most frequent adverse event observed during gastrointestinal endoscopy under procedural sedation. An optimum oxygen therapy has still not been conclusively determined., Design: A systematic review and network meta-analysis of randomized clinical trials., Setting: Digestive Endoscopy Center., Patients: Adults (≥18 years old and of both sexes) during gastrointestinal endoscopy under procedural sedation., Interventions: Pubmed, MEDLINE, Web of Science, Embase, and Clinicaltrials.gov. were searched until June 30, 2023. Randomized clinical trials (RCTs) comparing any oxygen therapy with another oxygen therapy or with placebo (nasal cannula, NC) were included., Measurement: The primary outcome was the incidence of hypoxemia, defined as the pulse oxygen saturation (SpO 2 ). Random-effects network meta-analyses were performed. Data are reported as odds ratios (OR), prediction intervals (PrI) and 95% CI. Bias risk was evaluated following the guidelines outlined by the Cochrane Collaboration. The quality of evidence was evaluated through the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework., Main Results: We included 27 RCTs with a total of 7552 patients. Compared to the use of NC, non-invasive positive pressure ventilation (NIPPV) demonstrated superior efficacy in mitigating hypoxemia (NIPPV vs. NC, OR = 0.16, 95% CI: 0.08-0.31, 95% PrI: 0.06-0.41), followed by Wei nasal jet tube (WNJT) (WNJT vs. NC, OR = 0.17, 95% CI: 0.10-0.30, 95% PrI: 0.07-0.42). The efficacy for preventing hypoxemia was ranked as follows: NIPPV > WNJT > oropharynx/nasopharyngeal catheter > high-flow nasal oxygenation > nasal mask > NC., Conclusions: During gastrointestinal endoscopy under procedural sedation, all other advanced oxygen therapies were found to be more efficacious than nasal cannula. NIPPV and WNJT appear to be the most efficacious oxygen therapy for preventing hypoxemia. Additionally, clinicians should make a choice regarding the most suitable oxygen therapy based on the risk population, type of endoscopy and adverse events., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objectives: To validate a method for continuously estimating the Pao 2 /Fio 2 (PF) ratio in all critically ill pediatric patients using only standard continuous data monitoring., Design: Retrospective study on a high temporal resolution database., Setting: PICU in Montreal, QC, Canada., Patients/subjects: We included any patients admitted from May 2015 to May 2023 who had an arterial blood gas (ABG) with concurrent continuous pulsed oximetry saturation (Spo 2 ) values. We used our previously validated mathematical model to determine the magnitude of hypoxemia by computing the estimated ePao 2 /Fio 2 (ePF) ratio and comparing it to the Spo 2 /Fio 2 (SF), using PF ratio as the reference standard., Interventions: None., Measurements and Main Results: We analyzed a total of 20,828 ABGs. When Spo 2 was below or equal to 97%, the ePF ratio showed a significantly better hypoxemia classification (none, light/moderate, or severe) than the SF ratio (0.80 vs. 0.72; p < 0.001), a lower fixed bias (16.26 vs. -35.24; p < 0.001), a lower mean absolute error (37.92 vs. 63.93; p < 0.001) and a lower proportional bias (slope of 1.01 vs. 0.81; p < 0.001). ePF ratio has also a better limits of agreement difference from Bland-Altman plot (248.10 vs. 292.45; p < 0.001) and coefficient of determination (0.68 vs. 0.59; p < 0.001). When Spo 2 was above 97%, the ePF ratio had better classification with Kappa (0.53 vs. 0.43; p < 0.001) and lower fixed bias (-0.63 vs. 65.68; p < 0.001)., Conclusions: The PF ratio based on ePF allows for a continuous estimation of hypoxemia severity with a better performance than the SF ratio., Competing Interests: The authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2024 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine.)

Background: Beneficial effects of breathing at [Formula: see text] < 0.21 on disease outcomes have been reported in previous preclinical and clinical studies. However, the safety and intra-hospital feasibility of breathing hypoxic gas for 5 d have not been established. In this study, we examined the physiologic effects of breathing a gas mixture with [Formula: see text] as low as 0.11 in 5 healthy volunteers., Methods: All 5 subjects completed the study, spending 5 consecutive days in a hypoxic tent, where the ambient oxygen level was lowered in a stepwise manner over 5 d, from [Formula: see text] of 0.16 on the first day to [Formula: see text] of 0.11 on the fifth day of the study. All the subjects returned to an environment at room air on the sixth day. The subjects' [Formula: see text], heart rate, and breathing frequency were continuously recorded, along with daily blood sampling, neurologic evaluations, transthoracic echocardiography, and mental status assessments., Results: Breathing hypoxia concentration dependently caused profound physiologic changes, including decreased [Formula: see text] and increased heart rate. At [Formula: see text] of 0.14, the mean [Formula: see text] was 92%; at [Formula: see text] of 0.13, the mean [Formula: see text] was 93%; at [Formula: see text] of 0.12, the mean [Formula: see text] was 88%; at [Formula: see text] of 0.11, the mean [Formula: see text] was 85%; and, finally, at an [Formula: see text] of 0.21, the mean [Formula: see text] was 98%. These changes were accompanied by increased erythropoietin levels and reticulocyte counts in blood. All 5 subjects concluded the study with no adverse events. No subjects exhibited signs of mental status changes or pulmonary hypertension., Conclusions: Results of the current physiologic study suggests that, within a hospital setting, delivering [Formula: see text] as low as 0.11 is feasible and safe in healthy subjects, and provides the foundation for future studies in which therapeutic effects of hypoxia breathing are tested., Competing Interests: Dr Mootha is listed as an inventor on patent applications filed by Massachusetts General Hospital on the therapeutic uses of hypoxia. Dr Berra is listed as the inventor on patent applications filed by Massachusetts General Hospital on the therapeutic uses of inhaled nitric oxide., (Copyright © 2024 by Daedalus Enterprises.)

Background: Pulse oximetry is a standart of anesthesia for perioperative monitoring. Due to the principles of Hb oxygen dissociation curve, peripheral oxygen saturation has an approximate sensitivity and specificity of 90% for the detection of hypoxemia., Objectives: The primary outcome of the study was to evaluate ORi Ⓡ as an early parameter to determine hypoxia in morbidly obese patients. The secondary outcome was to compare the effectiveness of ORi Ⓡ with SpO 2 in non-obese patients., Design: Prospective, observational study., Setting: Department of elective operating room at tertiary hospital., Patients and Methods: Observational study included written informed consent from 51 patients with 19 < BMI < 25 kg/m 2 and 51 patients with BMI > 40 kg/m 2 undergoing an elective surgery requiring tracheal intubation. In addition to standard monitors, an ORi sensor was placed and baseline values were recorded. The patients were preoxygenated until end tidal expiratory oxygen concentration is reached to 90%. After anesthesia induction and tracheal intubation, the breathing circuit was not connected tracheal tube until the SpO 2 decreased to 95%. Shapiro-Wilk, Pearson Chi-square, t-test, and Mann Whitney U test were used for the study., Main Outcome Measures: Times of tolerable apnea, ORi Ⓡ and SpO 2 values at the end of preoxygenation, beginning of intubation, beginning of the ORi alarm, when SpO 2 reached 95%, and when ORi reaches a plateau., Sample Size: 102 patients., Results: The alert period: time to reach ORi Ⓡ from 0.24 to a value of 95% SpO 2 was observed as 32 s in morbidly obese patients and 94 s in patients with a normal body mass index. The SpO 2 alert period was determined as time difference between 97% and 95% SpO 2 . The data were recorded as 15 s and 36 s, respectively. It was observed that tolerable apnea, ORi Ⓡ , SpO 2 and added alert times were longer in patients with normal BMI compared to morbidly obese patients., Conclusions: As a result, ORi Ⓡ can provide an early warning to prevent unexpected hypoxia before saturation begins to decrease in morbidly obese patients., Limitations: Inability to perform arterial blood gas sampling in the time periods when we looked at the parameters to determine the relationship between ORi Ⓡ and PaO 2 ., Gov Identifier: NCT05480748 registered 2022-07-29., (© 2024. The Author(s).)

Background: There is growing concern that pulse oximeters are routinely less accurate in hospitalized patients with darker skin pigmentation, in turn increasing risk of undetected (occult) hypoxemia and adverse clinical outcomes. The aim of this systematic review and meta-analysis was to synthesize evidence on racial and ethnic disparities in occult hypoxemia prevalence and clinical impacts of undetected hypoxemia., Methods: Ovid MEDLINE, Embase, and CINAHL databases were searched for relevant articles published through January 2024. Eligible studies must have been conducted among adults in inpatient or outpatient settings and report occult hypoxemia prevalence stratified by patient race or ethnicity, or clinical outcomes stratified by patient race or ethnicity and occult hypoxemia status. Screening for inclusion was conducted independently by two investigators. Data extraction and risk of bias assessment were conducted by one investigator then checked by a second. Outcome data were synthesized using random-effects meta-analyses., Results: Fifteen primary studies met eligibility criteria and reported occult hypoxemia prevalence in 732,505 paired oximetry measurements from 207,464 hospitalized patients. Compared with White patients, occult hypoxemia is likely more common among Black patients (pooled prevalence ratio = 1.67, 95% CI 1.47 to 1.90) and among patients identifying as Asian, Latinx, Indigenous, multiracial, or other race or ethnicity (pooled prevalence ratio = 1.39, 95% CI 1.19 to 1.64). Findings from studies reporting clinical outcomes suggest that Black patients with undetected hypoxemia may experience poorer treatment delivery outcomes than White patients with undetected hypoxemia. No evidence was found from outpatient settings., Discussion: This review and included primary studies rely on self-identified race or ethnicity, which may obscure variability in occult hypoxemia risk. Findings underscore that clinicians should be aware of the risk of occult hypoxemia in hospitalized patients with darker skin pigmentation. Moreover, oximetry data from included studies suggests that the accuracy of pulse oximeters could vary substantially from patient to patient and even within individual patients., Trial Registration: PROSPERO ( CRD42023402152 )., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Background: Nasal cannulas and face masks are common oxygenation tools used in conventional oxygen therapy for patients undergoing endoscopic surgery with sedation. However, as a novel supraglottic ventilation technique, the application of supraglottic jet oxygenation and ventilation (SJOV) in endoscopic surgery has not been well established., Method: We searched six electronic databases from inception to January 16, 2024, to assess the oxygenation/ventilation efficacy and side effects of the of SJOV in endoscopic surgery. The primary outcome was the incidence of hypoxemia. The secondary outcomes were the incidence of respiratory depression and adverse effects (nasal bleeding, sore throat, and dry mouth)., Results: Nine trials involving 2017 patients were included. The results demonstrated that the incidence of hypoxemia was lower in the SJOV group compared with the conventional oxygen therapy (COT) group [9 trails; 2017 patients; risk ratio (RR) = 0.18; 95% confidence interval (CI), (0.11-0.28)]. Subgroup analyses showed that SJOV reduced the incidence of hypoxemia in the high-risk group but had no effect on the low-risk group. The incidence of respiratory depression is lower in SJOV than in COT, but has increased side effects such as dry mouth. There was no statistically significant difference in nose bleeding or sore throat between the two groups., Conclusion: Compared with the COT, the SJOV decreased the incidence of hypoxemia in high-risk patients during endoscopic surgery with sedation. There was an increased risk of dry mouth, but not of nose bleeding or sore throat, during endoscopic surgery under sedation., Competing Interests: Declaration of competing interest All authors declare that there are no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The pathology of respiratory syncytial virus (RSV) infection remains unclear. An unbalanced immune response to RSV infection can lead to immunopathology, causing airway damage and impaired exchange of oxygen and carbon dioxide between the air and the bloodstream. We aimed to evaluate the association of the expression of inflammatory and antiviral genes in peripheral blood with severe hypoxemia in children with RSV infection seen in the hospital emergency room. We conducted a cross-sectional study on 121 RSV-infected children seen in hospital emergency rooms between 2015 and 2023. Total RNA was extracted from whole blood samples, and gene expression ( IL-6 , TNFα , CXCL8 , ISG15 , IFIT1 , RIGI , IFNβ , CCL5 , and CXCL10 ) was quantified using quantitative RT-PCR. The outcome variable was having severe hypoxemia (SpO 2 ≤ 90%). The association analysis was performed using a volcano plot, adjusted logistic regression, and orthogonal partial least squares discriminant analysis (OPLS-DA). We found that 26 of 121 children had severe hypoxemia (SpO 2 ≤ 90%). CXCL8 was overexpressed [fold changes (FC) > 2; q -value < 0.05], and ISG15 , IFIT1 , RIGI , IFNβ , CCL5 , and CXCL10 were underexpressed (FC <0.5; q -value <0.05) in children with severe hypoxemia. These associations were ratified using adjusted logistic regression. The OPLS-DA showed that the gene expressions of CXCL8 , ISG15 , IFIT1 , RIGI , and CXCL10 had values of variable importance in projection (VIP) ≥1, being the most relevant features. In conclusion, an imbalance favoring inflammation over antiviral defense may contribute to the pathogenesis of severe hypoxemia in RSV-infected children. These findings provide valuable insights into the pathology of RSV infection., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Pita-Martínez, Goez-Sanz, Virseda-Berdices, Gonzalez-Praetorius, Mazario-Martín, Rodriguez-Mesa, Quero-Delgado, Matías, Martínez and Resino.)

Background: Passengers on long-haul flights frequently consume alcohol. Inflight sleep exacerbates the fall in blood oxygen saturation (SpO 2 ) caused by the decreased oxygen partial pressure in the cabin. We investigated the combined influence of alcohol and hypobaric hypoxia on sleep, SpO 2 and heart rate., Methods: Two groups of healthy individuals spent either two nights with a 4-hour sleep opportunity (00:00-04:00 hours) in the sleep laboratory (n=23; 53 m above sea level) or in the altitude chamber (n=17; 753 hPa corresponding to 2438 m above sea level, hypobaric condition). Participants consumed alcohol before one of the nights (mean±SE blood alcohol concentration 0.043±0.003%). The order of the nights was counterbalanced. Two 8-hour recovery nights (23:00-07:00 hours) were scheduled between conditions. Polysomnography, SpO 2 and heart rate were recorded., Results: The combined exposure to alcohol and hypobaric condition decreased SpO 2 to a median (25th/75th percentile) of 85.32% (82.86/85.93) and increased heart rate to a median (25th/75th percentile) of 87.73 bpm (85.89/93.86) during sleep compared with 88.07% (86.50/88.49) and 72.90 bpm (70.90/78.17), respectively, in the non-alcohol hypobaric condition, 94.97% (94.59/95.33) and 76.97 bpm (65.17/79.52), respectively, in the alcohol condition and 95.88% (95.72/96.36) and 63.74 bpm (55.55/70.98), respectively, in the non-alcohol condition of the sleep laboratory group (all p<0.0001). Under the combined exposure SpO 2 was 201.18 min (188.08/214.42) below the clinical hypoxia threshold of 90% SpO 2 compared with 173.28 min (133.25/199.03) in the hypobaric condition and 0 min (0/0) in both sleep laboratory conditions. Deep sleep (N3) was reduced to 46.50 min (39.00/57.00) under the combined exposure compared with both sleep laboratory conditions (alcohol: 84.00 min (62.25/92.75); non-alcohol: 67.50 min (58.50/87.75); both p<0.003)., Conclusions: The combination of alcohol and inflight hypobaric hypoxia reduced sleep quality, challenged the cardiovascular system and led to extended duration of hypoxaemia (SpO 2 <90%)., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Inherited hemoglobin disorders are common in clinical practice. While qualitative (i.e. sickle cell disease) and quantitative (thalassemia) hemoglobinopathies are usually diagnosed clinically and confirmed through simple laboratory assessments, hemoglobin variants with altered oxygen affinity often go undetected due to their typically silent clinical presentation. Hemoglobin (Hb) J-Auckland, a low oxygen affinity hemoglobin variant first described in 1987 in Auckland, New Zealand, is one such silent disorder., Case Presentation: We report for the first time a clinically evident case of previously undiagnosed Hb J-Auckland in an 8-year-old girl who presented with unexplained hypoxemia at high altitude. Her oxygen level was corrected with supplemental oxygen and when assessed at low altitude. A brief discussion of the diagnostic approach and clinical implications is provided., Conclusion: Standard hemoglobin analysis is essential for the evaluation of suspected altered affinity hemoglobinopathy, and genetic testing is often required for definitive diagnosis. Early recognition and diagnosis of these variants can prevent mismanagement and improve patient outcomes.

Down syndrome (DS), the genetic condition caused by trisomy 21 (T21), is characterized by delayed neurodevelopment, accelerated aging, and increased risk of many co-occurring conditions. Hypoxemia and dysregulated hematopoiesis have been documented in DS, but the underlying mechanisms and clinical consequences remain ill defined. We report an integrative multi-omic analysis of ∼400 research participants showing that people with DS display transcriptomic signatures indicative of elevated heme metabolism and increased hypoxic signaling across the lifespan, along with chronic overproduction of erythropoietin, elevated biomarkers of tissue-specific hypoxia, and hallmarks of stress erythropoiesis. Elevated heme metabolism, transcriptional signatures of hypoxia, and stress erythropoiesis are conserved in a mouse model of DS and associated with overexpression of select triplicated genes. These alterations are independent of the hyperactive interferon signaling characteristic of DS. These results reveal lifelong dysregulation of key oxygen-related processes that could contribute to the developmental and clinical hallmarks of DS., Competing Interests: Declaration of interests J.M.E. has provided consulting services to Eli Lilly and Co., Gilead Sciences Inc., Biohaven Pharmaceuticals, and Perha Pharmaceuticals., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: When treating acute respiratory failure, both hypoxemia and hyperoxemia should be avoided. S pO 2 should be monitored closely and O 2 flows adjusted accordingly. Achieving this goal might be easier with automated O 2 titration compared with manual titration of fixed-flow O 2 . We evaluated the feasibility of using an automated O 2 titration device in subjects treated for acute hypoxemic respiratory failure in a tertiary care hospital., Methods: Health-care workers received education and training about oxygen therapy, and were familiarized with an automated O 2 titration device (FreeO 2, ). A coordinator was available from 8:00 am to 5:00 pm during weekdays to provide technical assistance. The ability of the device to maintain S pO 2 within the prescribed therapeutic window was recorded. Basic clinical information was recorded., Results: Subjects were enrolled from November 2020 to August 2022. We trained 508 health-care workers on the use of automated O 2 titration, which was finally used on 872 occasions in 763 subjects, distributed on the respiratory, COVID-19, and thoracic surgery wards, and in the emergency department. Clinical information could be retrieved for 609 subjects (80%) who were on the system for a median (interquartile range) of 3 (2-6) d, which represented 2,567 subject-days of clinical experience with the device. In the 82 subjects (14%) for whom this information was available, the system maintained S pO 2 within the prescribed targets 89% of the time. Ninety-six subjects experienced clinical deterioration as defined by the need to be transferred to the ICU and/or requirement of high flow nasal oxygen but none of these events were judged to be related to the O 2 device., Conclusions: Automated O 2 titration could be successfully implemented in hospitalized subjects with hypoxemic respiratory failure from various causes. This experience should foster further improvement of the device and recommendations for an optimized utilization., Competing Interests: Drs Simon, Lacasse, Lellouche, and Maltais are shareholders of Oxynov, the maker of FreeO2; Dr Lellouche is co-founder of Oxynov., (Copyright © 2024 by Daedalus Enterprises.)

Obstructive sleep apnea (OSA) is a sleep disorder that has been associated with the incidence of other pathologies. Diagnosis is mainly based on the apnea-hypopnea index (AHI) obviating other repercussions such as intermittent hypoxemia, which has been found to be associated to cardiovascular complications. Blood-based samples and urine have been the most utilised biofluids in metabolomics studies related to OSA, while sweat could be an alternative due to its non-invasive and accessible sampling, its reduced complexity, and comparability with other biofluids. Therefore, this research aimed to evaluate metabolic overnight changes in sweat collected from patients with OSA classified according to the AHI and oxygen desaturation index (ODI), looking for potential cardiovascular repercussions. Pre- and post-sleeping sweat samples from all individuals (n = 61) were analysed by gas chromatography coupled to high-resolution mass spectrometry after appropriate sample preparation to detect as many metabolites as possible. Permanent significant alterations in the sweat were reported for pyruvate, serine, lactose, and hydroxybutyrate. The most relevant overnight metabolic alterations in sweat were reported for lactose, succinate, urea, and oxoproline, which presented significantly different effects on factors such as the AHI and ODI for OSA severity classification. Overall metabolic alterations mainly affected energy production-related processes, nitrogen metabolism, and oxidative stress. In conclusion, this research demonstrated the applicability of sweat for evaluation of OSA diagnosis and severity supported by the detected metabolic changes during sleep., (© 2023 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.)

Purpose: Skin pigmentation influences peripheral oxygen saturation (SpO 2 ) compared to arterial saturation of oxygen (SaO 2 ). Occult hypoxemia (SaO 2  ≤ 88% with SpO 2  ≥ 92%) is associated with increased in-hospital mortality in venovenous-extracorporeal membrane oxygenation (VV-ECMO) patients. We hypothesized VV-ECMO cannulation, in addition to race/ethnicity, accentuates the SpO 2 -SaO 2 discrepancy due to significant hemolysis., Methods: Adults (≥ 18 years) supported with VV-ECMO with concurrently measured SpO 2 and SaO 2 measurements from over 500 centers in the Extracorporeal Life Support Organization Registry (1/2018-5/2023) were included. Multivariable logistic regressions were performed to examine whether race/ethnicity was associated with occult hypoxemia in pre-ECMO and on-ECMO SpO 2 -SaO 2 calculations., Results: Of 13,171 VV-ECMO patients, there were 7772 (59%) White, 2114 (16%) Hispanic, 1777 (14%) Black, and 1508 (11%) Asian patients. The frequency of on-ECMO occult hypoxemia was 2.0% (N = 233). Occult hypoxemia was more common in Black and Hispanic patients versus White patients (3.1% versus 1.7%, P < 0.001 and 2.5% versus 1.7%, P = 0.025, respectively). In multivariable logistic regression, Black patients were at higher risk of pre-ECMO occult hypoxemia versus White patients (adjusted odds ratio [aOR] = 1.55, 95% confidence interval [CI] = 1.18-2.02, P = 0.001). For on-ECMO occult hypoxemia, Black patients (aOR = 1.79, 95% CI = 1.16-2.75, P = 0.008) and Hispanic patients (aOR = 1.71, 95% CI = 1.15-2.55, P = 0.008) had higher risk versus White patients. Higher pump flow rates (aOR = 1.29, 95% CI = 1.08-1.55, P = 0.005) and on-ECMO 24-h lactate (aOR = 1.06, 95% CI = 1.03-1.10, P < 0.001) significantly increased the risk of on-ECMO occult hypoxemia., Conclusion: SaO 2 should be carefully monitored if using SpO 2 during ECMO support for Black and Hispanic patients especially for those with high pump flow and lactate values at risk for occult hypoxemia., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Objectives: This study examined the effects of acute normoxic and hypoxic exposure on neuromuscular and hemodynamic physiological responses performed during dynamic step muscle actions., Methods: Thirteen recreationally active men (mean ± SD age: 21.2 ± 2.9 yrs) performed dynamic leg extensions unilaterally under Normoxic (FiO 2  = 21 %) and Hypoxic (FiO 2  = 13 %) conditions in a randomized order at 20 %, 40 %, 60 %, 80 %, and 100 % of their maximal strength. Electromyographic (EMG) amplitude, EMG frequency, (Oxygenated and Deoxygenated hemoglobin; Oxy Hb , Deoxy Hb) , Total hemoglobin (Total Hb ), and skeletal muscle tissue oxygenation status (StO 2 ) were measured from the vastus lateralis during all contractions., Results: There were no detectable differences in the neuromuscular responses between normoxia and hypoxia for EMG amplitude (p = 0.37-0.74) and frequency (p = 0.17-0.83). For EMG amplitude there were general increases with intensity (p < 0.01-0.03). EMG frequency remained similar from 20% to 80% and then increased at 100 % effort (p = 0.02). There was no significant difference in patterns of responses for Oxy Hb (p = 0.870) and Total Hb (p = 0.200) between normoxia and hypoxia. StO 2 (p = 0.028) decreased and Deoxy Hb (p = 0.006) increased under hypoxia compared to normoxia during dynamic step muscle actions performed in a randomized order., Conclusion: Unlike fatigue, acute hypoxemia in an unfatigued state does not impact the localized neuromuscular responses, but minimally impacts the hemodynamic responses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Pulse oximetry is arguably the most impactful monitor ever introduced into respiratory care practice. Recently there has been increased attention to the problem of occult hypoxemia in which patients are hypoxemic despite an acceptable S pO 2 Although occult hypoxemia might be greater in Black patients than white patients, it is not insignificant in whites. In a given population of patients, the bias between S pO 2 and arterial oxygen saturation (S aO 2 ) might be close to zero. However, the limits of agreement can be wide, meaning that S pO 2 might overestimate S aO 2 in many individual patients, which can result in occult hypoxemia in some. Manufactures report accuracy of S pO 2 derived from normal individuals, which might differ from that in the clinical setting. That S pO 2 overestimates S aO 2 in an important number of individuals has caused some to recommend higher S pO 2 targets to avoid occult hypoxemia. There is also evidence that suggests that S pO 2 might not accurately trend S aO 2 Additional research is needed to investigate strategies to mitigate the bias between S pO 2 and S aO 2 Clinicians must be cognizant of the limitations of pulse oximetry when clinically using S pO 2 The aim of this paper is to provide an update on pulse oximetry., Competing Interests: Dr Hess discloses relationships with Daedalus Enterprises, American Association for Respiratory Care, Massachusetts General Hospital, Northeastern University, University of Pittsburgh, Lungpacer, Jones & Bartlett, McGraw Hill, and UpToDate. Dr Hess is Managing Editor of Respiratory Care., (Copyright © 2024 by Daedalus Enterprises.)

Introduction: Hypoxemia is a common complication of childhood respiratory tract infections and non-respiratory infections. Hypoxemic children have a five-fold increased risk of death compared to children without hypoxemia. In addition, there is limited evidence about hypoxemia and clinical predictors in Ethiopia. Therefore, this study was conducted to assess the prevalence and clinical predictors of hypoxemia among children with respiratory distress admitted to the University of Gondar Comprehensive Specialized Hospital., Methods: An institutional-based cross-sectional study was conducted from December 2020 to May 2021 in northwest Ethiopia. A total of 399 study participants were selected using systematic random sampling. The oxygen saturation of the child was measured using Masimo rad-5 pulse oximetry. SPSS version 21 software was used for statistical analysis., Result: In this study, the prevalence of hypoxemia among children with respiratory distress was 63.5%. The clinical signs and symptoms significantly associated with hypoxemia were: head-nodding (AOR: 4.1, 95% CI: 1.81-9.28) and chest indrawing (AOR: 3.08, 95% CI: 1.32-7.16) which were considered statistically the risk factors for hypoxemia while inability to feed (AOR: 0.13, 95% CI: 0.02-0.77) was the protective factor for hypoxemia. The most sensitive predictors of hypoxemia were fast breathing with sensitivity (98.4%), nasal flaring (100.0%), chest indrawing (83.6%), and intercostal retraction (93.1%). The best specific predictors of hypoxemia were breathing difficulty with specificity (79.4%), inability to feed (100.0%), wheezing (83.0%), cyanosis (98.6%), impaired consciousness (94.2%), head-nodding (88.7%), and supra-sternal retraction (96.5%)., Conclusion and Recommendation: The prevalence of hypoxemia among children was high. The predictors of hypoxemia were the inability to feed, head nodding, and chest indrawing. It is recommended that the health care settings provide immediate care for the children with an inability to feed, head nodding, and chest indrawing. The policymakers better to focus on preventive strategies, particularly those with the most specific clinical predictors., (© 2024. The Author(s).)

Competing Interests: Funding Support and Author Disclosures The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

The postoperative period is critical for the development of complications, including hypoxemia. To detect hypoxemia early and provide appropriate care, continuous monitoring of saturation is necessary: pulse oximetry is an easily accessible and simple method for this purpose. However, a SpO 2 cut-off value to detect hypoxemia in dogs recovering from general anesthesia is lacking in the veterinary literature. The objectives of this clinical study are to validate the room air SpO 2 test (SpAT), to identify a cut-off value to discriminate hypoxemia (Phase 1), and to apply the SpAT to study the incidence of transient postoperative hypoxemia (TPH) (Phase 2) in dogs with healthy lungs recovering from general anesthesia. Phase 1: 87 dogs recovering from general anesthesia with an arterial line were included. After extubation, SpAT was performed simultaneously with arterial blood sampling. A PaO 2 < 80 mmHg was considered hypoxemia. Phase 2: 654 dogs were enrolled. They underwent general anesthesia with different ventilation settings for different procedures. After extubation, dogs were classified as hypoxemic if the SpO 2 was lower than the cut-off obtained in phase 1. Phase 1 showed that the SpO 2 cut-off is < 95% (sensitivity 100%, specificity 97.4%; area under the curve, AUC = 0.996; 95% Confidence Interval = 0.944-1; P<0.0001). In Phase 2, 169 dogs were hypoxemic. Body Condition Score (BCS) > 3/5, dorsal recumbency, FiO 2 1, absence of Positive End-Expiratory Pressure (PEEP) had a significant odds ratio to induce TPH (5.8, 1.9, 3.7, 1.7, respectively). These results showed that SpO 2 < 95% indicates PaO 2 < 80 mmHg in dogs and TPH occurs in up to 28% of cases. Identification of associated risks could be useful to prevent and to increase awareness for monitoring and treatment., Competing Interests: Declaration of Competing Interest None of the authors has any financial or personal relationships that could inappropriately influence or bias the content of the paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Hypoxemia can occur in people at ultra-high altitude (above 3500 m) even at rest, and patients undergoing gastroscopy under general anesthesia have higher risk of hypoxemia. Supplementary oxygen via standard nasal cannula (SNC) is the standard of care for most patients who undergo gastroscopy under general anesthesia, which provides oxygen flow up to 15 L/min. High-flow nasal cannula (HFNC) could deliver oxygen at a rate up to 60 L/min, which is recommended by the American Society of Anesthesiologists Practice Guidelines. We speculated that the benefit with HFNC is more prominent in high-altitude areas, and aimed to compare the incidence of hypoxemia during gastroscopy under general anesthesia at ultra-high altitude with oxygen supply via either HFNC or SNC., Methods: The trial was registered at at Chinese Clinical Trial Registry (ChiCTR2100045513; date of registration on 18/04/2021). Adult patients undergoing gastroscopy with anesthesia (estimated duration of anesthesia at ≥ 15 min) were randomized at a 1:1 ratio to receive HFNC oxygen or SNC oxygen. The primary outcome was hypoxemia (SpO 2  < 90% for any duration). Secondary outcomes included severe hypoxemia (SpO 2  < 75% for any duration or SpO 2  < 90% but ≥ 75% for ≥ 60 s) and hypotension, as defined by reduction of mean arterial blood pressure by ≥ 25% from the baseline., Results: A total of 262 patients were enrolled: 129 in the HFNC group and 133 in the SNC group. All patients received the designated intervention. Student's t-test, Mann-Whitney U test and χ 2 test were employed in the study. The rate of hypoxemia was 9.3% (12/129) in the HFNC group versus 36.8% (49/133) in the SNC group [risk ratio (95% confidence interval): 0.25(0.14-0.45); P < 0.001). The HFNC group also had lower rate of severe hypoxemia [0.0% (0/129) versus 11.3% (15/133); risk ratio (95% confidence interval): 0.03(0.00-0.55); P < 0.001, respectively]. The rate of hypotension did not differ between the 2 groups [22.5% (29/129) in HFNC group versus 21.1% (28/133) in SNC group; risk ratio (95% confidence interval): 1.07(0.67-1.69) ; P = 0.779]., Conclusion: HFNC oxygen reduced the incidence of hypoxemia during anesthesia in adult patients undergoing gastroscopy at ultra-high altitude., (© 2024. The Author(s).)

Background: Hypoxemia represents the most prevalent adverse event during flexible bronchoscopy procedures aimed at foreign body retrieval in pediatric patients; if not expeditiously managed, it carries the potential for cardiac or respiratory arrest. The specific risk factors contributing to the occurrence of hypoxemia during foreign body FB removal via bronchoscopy have yet to be definitively established., Methods: This retrospective study included a cohort of 266 pediatric subjects from January 1, 2015, to December 31, 2022, who underwent flexible bronchoscopy for the purpose of FB extraction. In this cohort, the supraglottic airway was used to connect the anesthesia apparatus during the removal procedure., Results: In total, 45 of the pediatric patients (16.9%) experienced episodes of hypoxemia during the FB removal procedure. Multivariate analysis revealed that the following factors were significantly associated with the occurrence of hypoxemia: an operation time exceeding 60 min (odds ratio [OR] 8.55; 95% confidence interval [CI] 3.82-19.13), a maximum diameter exceeding 7 mm (OR 5.03; 95% CI, 2.24-11.29), and the presence of radiological evidence indicating pneumonia (OR 2.69; 95% CI, 1.27-5.69)., Conclusion: During flexible bronchoscopy procedures aimed at FB removal in pediatric patients, there is an increased susceptibility to hypoxemia. Factors including extended operation duration, larger FB dimensions, and radiographic evidence suggestive of pneumonia significantly contribute to a heightened risk of hypoxemia., (© 2024. The Author(s).)

Importance: Patients presenting to the emergency department (ED) with hypoxemia often have mixed or uncertain causes of respiratory failure. The optimal treatment for such patients is unclear. Both high-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) are used., Objectives: We sought to compare the effectiveness of initial treatment with HFNC versus NIV for acute hypoxemic respiratory failure., Design Setting and Participants: We conducted a retrospective cohort study of patients with acute hypoxemic respiratory failure treated with HFNC or NIV within 24 hours of arrival to the University of Michigan adult ED from January 2018 to December 2022. We matched patients 1:1 using a propensity score for odds of receiving NIV., Main Outcomes and Measures: The primary outcome was major adverse pulmonary events (28-d mortality, ventilator-free days, noninvasive respiratory support hours) calculated using a win ratio., Results: A total of 1154 patients were included. Seven hundred twenty-six (62.9%) received HFNC and 428 (37.1%) received NIV. We propensity score matched 668 of 1154 (57.9%) patients. Patients on NIV versus HFNC had lower 28-day mortality (16.5% vs. 23.4%, p = 0.033) and required noninvasive treatment for fewer hours (median 7.5 vs. 13.5, p < 0.001), but had no difference in ventilator-free days (median [interquartile range]: 28 [26, 28] vs. 28 [10.5, 28], p = 0.199). Win ratio for composite major adverse pulmonary events favored NIV (1.38; 95% CI, 1.15-1.65; p < 0.001)., Conclusions and Relevance: In this observational study of patients with acute hypoxemic respiratory failure, initial treatment with NIV compared with HFNC was associated with lower mortality and fewer composite major pulmonary adverse events calculated using a win ratio. These findings underscore the need for randomized controlled trials to further understand the impact of noninvasive respiratory support strategies., Competing Interests: Dr. Munroe was supported by grant number T32 HL 007749 (Multidisciplinary Training Program in Lung Disease), grant number F32 HL 172463 and grant number L30 HL 170379 (Loan Repayment Award) from the National Institutes of Health (NIH) and the National Heart, Lung, and Blood Institute (NHLBI). This work was also supported in part by a grant from NIH (NINDS and NHLBI) for infrastructure for the Clinical Coordinating Center for the Strategies to Innovate EmeRgENcy Care Clinical Trials Network—2U24NS100659. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. This article does not represent the views of the Department of Veterans Affairs or the U.S. government. Dr. Mosier has received travel support from Fisher & Paykel. The remaining authors have disclosed that they do not have any potential conflicts of interest.

Robot-assisted laparoscopic radical prostatectomy (RALP) has emerged as an effective treatment for prostate cancer with obvious advantages. This study aims to identify risk factors related to hypoxemia during the emergence from anesthesia in patients undergoing RALP. A cohort of 316 patients undergoing RALP was divided into two groups: the hypoxemia group (N = 134) and the non-hypoxemia group (N = 182), based on their postoperative oxygen fraction. Comprehensive data were collected from the hospital information system, including preoperative baseline parameters, intraoperative data, and postoperative recovery profiles. Risk factors were examined using multiple logistic regression analysis. The study showed that 38.9% of patients had low preoperative partial pressure of oxygen (PaO 2 ) levels. Several clinical parameters showed significant differences between the hypoxemia group and the non-hypoxemia group, including weight (P < 0.0001), BMI (P < 0.0001), diabetes mellitus (P = 0.044), history of emphysema and pulmonary alveoli (P < 0.0001), low preoperative PaO 2 (P < 0.0001), preoperative white blood cell count (P = 0.012), preoperative albumin (P = 0.048), intraoperative bleeding (P = 0.043), intraoperative CO 2 accumulation (P = 0.001), duration of surgery (P = 0.046), postoperative hemoglobin level (P = 0.002), postoperative hypoxemia (P = 0.002), and early postoperative fever (P = 0.006). Multiple logistic regression analysis revealed BMI (adjusted odds ratio = 0.696, 95% confidence interval 0.612-0.719), low preoperative PaO 2 (adjusted odds ratio = 9.119, 95% confidence interval 4.834-17.203), and history of emphysema and pulmonary alveoli (adjusted odds ratio = 2.804, 95% confidence interval 1.432-5.491) as independent factors significantly associated with hypoxemia on emergence from anesthesia in patients undergoing RALP. Our results demonstrate that BMI, lower preoperative PaO 2 , and a history of emphysema and pulmonary alveolar disease are independent risk factors associated with hypoxemia on emergence from anesthesia in patients undergoing RALP. These findings provide a theoretical framework for surgeons and anesthesiologists to facilitate strategies to mitigate postoperative hypoxemia in this unique patient population., (© 2024. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

Acute type A aortic dissection is a life-threatening cardiovascular disease characterized by rapid onset and high mortality. Emergency surgery is the preferred and reliable treatment option. However, postoperative complications significantly impact patient prognosis. Hypoxemia, a common complication, poses challenges in clinical treatment, negatively affecting patient outcomes and increasing the risk of mortality. Therefore, it is crucial to study and comprehend the risk factors and treatment strategies for hypoxemia following acute type A aortic dissection to facilitate early intervention., (© 2024. The Author(s).)

Introduction: The Roth score is an alternative strategy to estimate oxygen saturation by using a simple verbal test. We designed this clinical study to assess the validity of the Roth score (Spanish version) as a screening test for hypoxemia. A secondary objective was to evaluate the agreement and consistency between the oxygen saturation obtained via pulse oximetry (SpO 2 ) and arterial blood gas test (SaO 2 )., Methods: An observational study was conducted in two hospital emergency departments. Adult patients who underwent arterial blood gas tests were included in the analysis. Pulse oximetry values were determined, and the Roth score was applied in the Spanish language. The validity of the Roth score was assessed in terms of sensitivity and specificity by creating ROC curves and by calculating the area under the curve (AUC) for SpO 2 , SaO 2 , and oxygen pressure in the arterial blood (PaO 2 ). Agreement between SpO 2 and SaO 2 values was assessed by using the intraclass correlation coefficient (ICC), and consistency between both measures was calculated by following the method of Bland and Altman., Results: The ROC curve models of the Roth score results that were obtained for SaO 2 < 90%, ≤92%, and < 95% had AUCs of 0.574, 0.462, and 0.543, respectively, for the highest number that was obtained in the test, as well as AUCs of 0.403, 0.376, and 0.495, respectively, for the maximum time that was used. The AUCs for PaO 2 ≤ 60, ≤70, and ≤80 mmHg were 0.534, 0.568, and 0.512, respectively, for the maximum number that was obtained in the test, as well as AUCs of 0.521, 0.515, and 0.519, respectively, for the maximum time that was spent. The ICC between SaO 2 and SpO 2 was 0.817 (p < 0.001); additionally, the mean difference between the two measurements was -0.55., Conclusion: The Roth score performed in Spanish is not a valid test for hypoxemia screening. There is sufficient agreement and consistency between SaO 2 and SpO 2 measurements., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

Objectives: This study examined effects of acute hypoxia on the neuromuscular responses (electromyographic (EMG) amplitude and EMG frequency) and localized muscle tissue oxygenated hemoglobin (oxygenated hemoglobin (Oxy Hb ), deoxygenated hemoglobin (Deoxy Hb ), total hemoglobin (Total Hb ), and muscle tissue oxygenation saturation (StO 2 ) during the process of fatigue., Methods: Fifteen male participants (21.4±2.8yr) performed leg extension repetitions to failure at 70% 1-repetition maximum until volitional exhaustion under Normoxic (FiO 2 :21%) and Hypoxic (FiO 2 :12.9%) conditions. Electromyographic amplitude, EMG frequency, Oxy Hb , Deoxy Hb , Total Hb , and StO 2 were measured from the vastus lateralis at Initial, 20, 40, 60, 80, and 100% of the repetitions to failure., Results: There was no significant difference in the patterns of responses for EMG amplitude, Oxy Hb , or Deoxy Hb between Normoxia and Hypoxia. For EMG frequency, Hypoxia was greater than Normoxia and decreased with fatigue. Total Hb and StO 2 were greater under Normoxia compared to Hypoxia. The patterns of responses for EMG amplitude, Deoxy Hb , and Total Hb increased throughout the repetitions to failure. Oxy Hb and StO 2 exhibited decreases throughout the repetitions to failure for Normoxic and Hypoxic conditions., Conclusion: The EMG and oxygenation measurements non-invasively suggest a sympathoexcitatory response (indicated by EMG frequency) and provided complimentary information regarding the process of fatigue in normoxic and hypoxic states., Competing Interests: The authors have no conflict of interest.

Objectives/background: Interest in using blood oxygen desaturations in the diagnostics of sleep apnea has risen in recent years. However, no standardized criteria for desaturation scoring exist which complicates the drawing of solid conclusions from literature., Patients/methods: We investigated how different desaturation scoring criteria affect the severity of nocturnal hypoxic load and the prediction of impaired daytime vigilance in 845 patients. Desaturations were scored based on three features: 1) minimum oxygen saturation drop during the event (2-20%, 1% interval), 2) minimum duration of the event (2-20s, 1s interval), and 3) maximum plateau duration within the event (5-60s, 5s interval), resulting in 4332 different scoring criteria. The hypoxic load was described with oxygen desaturation index (ODI), desaturation severity (DesSev), and desaturation duration (DesDur) parameters. Association between hypoxic load and impaired vigilance was investigated with covariate-adjusted area under curve (AUC) analyses by dividing patients into normal (≤5 lapses) and impaired (≥36 lapses) vigilance groups based on psychomotor vigilance task performance., Results: The severity of hypoxic load varied greatly between different scoring criteria. For example, median ODI ranged between 0.4 and 12.9 events/h, DesSev 0.01-0.23 %-point, and DesDur 0.3-9.6 %-point when the minimum transient drop criterion of 3% was used and other two features were altered. Overall, the minimum transient drop criterion had the largest effect on parameter values. All models with differently determined parameters predicted impaired vigilance moderately (AUC = 0.722-0.734)., Conclusions: Desaturation scoring criteria greatly affected the severity of hypoxic load. However, the difference in the prediction of impaired vigilance between different criteria was rather small., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

In a recent publication in BMC Anesthesiology, Rincon, et al.present accuracy data for three pulse oximeters with sensors located at three different anatomic sites. Their results for the Masimo Radical with fingertip sensor are erroneous, and we present valid data here. Rincon, et al.show a Bias ± Precision of 2.02 ± 4.6, while the correct laboratory values are -0.01 ± 1.16. The most probable reason for these invalid data is that insufficient time was used at each saturation plateau to allow stabilization of SpO 2 readings on a fingertip sensor. It has been shown in the literature that fingertip sensors require at least a full minute of stable oxygenation conditions before their readings will be the same as earlobe sensors., (© 2022. The Author(s).)

Obese patients undergoing esophagogastroduodenoscopy procedures require sedation ranging between deep sedation and general anesthesia to tolerate the procedure which predisposes this patient population to hypoxemia development. A practical, cost-effective, and readily available means of preoxygenation that can be implemented by certified registered nurse anesthetists practicing in high-volume, fast-paced ambulatory gastrointestinal endoscopy centers is the use of a nonrebreathing face mask with reservoir bag and one-way exhalation valve, along with oxygen flow rates at 15 liters per minute, and instructing the patient in taking eight vital capacity deep breaths over 60 seconds prior to start of the procedure. The purpose of this quality improvement project was to reduce intraprocedural hypoxemic events, defined as intraprocedural SpO 2 values ≤ 90%, in obese patients undergoing esophagogastroduodenoscopy procedures with deep sedation using propofol. At baseline, 30.8% obese patients undergoing esophagogastroduodenoscopy procedures experienced hypoxemic events. Following preoxygenation, hypoxemic events were reduced to 14.3% with chi-square analysis showing statistical significance (χ 2 = 8.859, P =.003). Preoxygenation of obese patients prior to esophagogastroduodenoscopy procedures is an evidence-based practice that can reduce hypoxemic event occurrence during the procedure and improve patient safety., Competing Interests: Name: Russ Branch, DNP, CRNA, ACNP-BC Contribution: This author made significant contributions to the conception, synthesis, writing, and final editing and approval of the manuscript to justify inclusion as an author. Disclosures: None. Name: Haley Hoy, PhD, ACNP-BC Contribution: This author made significant contributions to the conception, synthesis, writing, and final editing and approval of the manuscript to justify inclusion as an author. Disclosures: None. Name: Katina Currin, DNP, CRNA Contribution: This author made significant contributions to the conception, synthesis, writing, and final editing and approval of the manuscript to justify inclusion as an author. Disclosures: None. The authors did not discuss off-label use within the article. Disclosure statements are available for viewing upon request., (Copyright © by the American Association of Nurse Anesthetists.)

Prolonged perinatal asphyxia and subsequent severe hypoxia are the main causes of mortality in neonatal dogs in the first days of life. In medicine, specific cardiac biochemical markers, such as troponin I, are used to diagnose ischemic and nonischemic myocardial injury in asphyxiated newborns after birth. Thus, the objectives of this study were to compare the levels of cardiac troponin I (cTnI) between asphyxiated and nonasphyxiated newborn dogs and evaluate the correlations of cTnI levels with the modified Apgar score, the levels of oxygen saturation, blood glucose, and lactatemia, and blood gas parameters. This study aimed to determine the possible use of cTnI as a marker of severe hypoxia and myocardial ischemic injury in neonatal dogs. Fifteen animals in a eutocic vaginal delivery group (VG), 15 animals in a cesarean section group (CG), and 13 animals in a hypoxia (asphyxiated) group (HG) were evaluated. The animals in the asphyxiated group were from dystocic deliveries and born by vaginal delivery or cesarean section. All groups were evaluated at birth and after 60 min. The newborns in the VG and CG exhibited mixed acidosis (respiratory acidosis due to increased partial pressure of CO 2 (pCO 2 ) and metabolic acidosis due to reduced pH and bicarbonate (HCO 3 ) levels, base excess/deficit in the extracellular fluid compartment (BEecf), and increased lactate levels) due to transient physiological hypoxemia at birth. The cTnI levels in the VG and CG were within the reference standards for healthy dogs. No correlations between cTnI level and the other parameters were observed in the VG and CG. Newborns in the HG exhibited prominent mixed acidosis (p < 0.05) due to severe hypoxemia. The Apgar score and blood gas parameters showed that these dogs were born asphyxiated, and they presented low vitality and the need for resuscitation maneuvers. The cTnI levels in the HG were significantly higher than those in the VG and CG (p < 0.05) and above the reference standards for healthy dogs, which indicated ischemic myocardial injury. The cTnI level was negatively correlated (p < 0.05) with the parameters Apgar score, heart rate, peripheral oxygen saturation (sO 2 ) level, reflex score, and total carbon dioxide (TCO 2 ) level and positively correlated (p < 0.01) with lactate level. This study showed that asphyxiated newborn dogs have higher serum cTnI levels than nonasphyxiated newborn dogs; thus, the cTnI can be used as a marker of severe hypoxia and ischemic myocardial damage in newborn dogs., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Studies evaluating the role of high-flow nasal cannula (HFNC) in sedated digestive endoscopy have reported conflicting results. This meta-analysis evaluates the effectiveness of HFNC in patients undergoing digestive endoscopy procedures under sedation., Methods: PubMed, Medline, EMBASE, Cochrane Central Register of Controlled Trials and Web of Science, were searched from inception to 31 July 2021. Only randomized clinical trials comparing HFNC with standard nasal cannula oxygen (SNC) during sedated digestive endoscopy were included. The incidence of hypoxemia was the primary outcome, and the secondary outcome was the percentage of patients who needed airway interventions., Results: Seven studies that enrolled 2998 patients were included. When compared to SNC, HFNC was associated with a significant reduction in hypoxemia incidence (OR 0.24, 95% CI 0.09 to 0.64) and airway intervention requirements (OR 0.15, 95% CI 0.03 to 0.69), with both high heterogeneity (I 2  = 81% and 94%). In subgroup analysis, when hypoxemia was defined as pulse oxygen saturation (SpO 2 ) < 90%, low risk of hypoxemia subjects who received HFNC were associated with a significant reduction in hypoxemia incidence (OR 0.02, 95% CI 0.00 to 0.07; heterogeneity I 2  = 39%) and airway intervention requirements (OR 0.02, 95% CI 0.01 to 0.04; heterogeneity I 2  = 15%). However, in the high risk of hypoxemia subjects, there were no significant differences between the two oxygen administration techniques in both primary (OR 0.81, 95% CI 0.36 to 1.78; heterogeneity I 2  = 0%) and secondary outcomes (OR 0.85, 95% CI 0.46 to 1.59; heterogeneity I 2  = 0%)., Conclusions: Compared to SNC, HFNC not only reduce the incidence of hypoxemia but also reduce the requirements for airway interventions during sedated digestive endoscopy procedures, especially in patients at low risk for hypoxemia. In high risk of hypoxemia patients, there were no significant differences between the two oxygen administration techniques. Trial registration PROSPERO International prospective register of systematic reviews on 28 July 2021, registration no. CRD42021264556., (© 2022. The Author(s).)

Objective: The goal of this study was to verify the details of neonatal respiratory inhibition (NRI) in healthy infants., Methods: We screened for NRI in 521 infants who weighed at least 2000 g and who were born at a gestational age of at least 36 weeks. Respiratory inhibition was defined as severe hypoxemia, accompanied by clinical manifestations of central cyanosis and a decrease in SpO 2 to less than 70%. NRI consists of feeding hypoxemia, respiratory inhibition after crying (RIAC), and respiratory inhibition after gastroesophageal reflux (RIGER). The subjects were monitored continuously via pulse oximetry from birth until discharge. To identify the details of NRI, we analyzed detailed notes taken by both parents and medical staff during monitoring using specific software designed to interpret pulse oximetry measurements. The mothers of infants with feeding hypoxemia received nursing guidance., Results: NRI was observed in 268 (51.4%) infants (feeding hypoxemia in 227 (43.6%); RIAC in 121 (23.2%); and RIGER in 12 (2.3%)). Among perinatal factors, NRI was related to diabetes mellitus ( p  = .008; odds ratio = 3.290; 95% CI: 1.371-7.895), twin pregnancy ( p  = .032; odds ratio = 2.061; 95% CI: 1.062-3.998), and cesarean section ( p  = .036; odds ratio = 1.537; 95% CI: 1.027-2.299) using multiple logistic regression analysis. Almost all infants with RIAC and RIGER, even those with severe cases, recovered until discharge. However, 93 (41.0%) infants with feeding hypoxemia needed additional feeding control after being discharged. Despite the provision of nursing guidance in feeding control, 143 (63.0%) infants experienced feeding hypoxemia continuously. The more frequently the infants experienced feeding hypoxemia, the more severe the degree of feeding hypoxemia became. Breastfeeding reduced the frequency and degree of feeding hypoxemia compared to bottle-feeding., Conclusions: NRI was often observed in healthy infants. Breastfeeding and careful feeding control should be recommended to mothers of infants with repeated feeding hypoxemia.

Clinical trials of therapeutics for traumatic brain injury (TBI) demonstrating preclinical efficacy for TBI have failed to replicate these results in humans, in part due to the absence of clinically feasible therapeutic windows for administration. Minocycline, an inhibitor of microglial activation, has been shown to be neuroprotective when administered early after experimental TBI but detrimental when administered chronically to human TBI survivors. Rather than focusing on the rescue of primary injury with early administration of therapeutics which may not be clinically feasible, we hypothesized that minocycline administered at a clinically feasible time point (24 h after injury) would be neuroprotective in a model of TBI plus delayed hypoxemia. We first explored several different regimens of minocycline dosing with the initial dose 24 h after injury and 2 h prior to hypoxemia, utilizing short-term neuropathology to select the most promising candidate. We found that a short course of minocycline reduced acute microglial activation, monocyte infiltration and hippocampal neuronal loss at 1 week post injury. We then conducted a preclinical trial to assess the long-term efficacy of a short course of minocycline finding reductions in hippocampal neurodegeneration and synapse loss, preservation of white matter myelination, and improvements in fear memory performance at 6 months after injury. Timing in relation to injury and duration of minocycline treatment and its impact on neuroinflammatory response may be responsible for extensive neuroprotection observed in our studies., (© 2022. The Author(s).)

Background: Our goal is to investigate the use of the oxygen reserve index (ORi) to detect hypoxemia and its relation with parameters such as; peripheral oxygen saturation, perfusion index (PI), and pleth variability index (PVI) during one-lung ventilation (OLV)., Methods: Fifty patients undergoing general anesthesia and OLV for elective thoracic surgeries were enrolled in an observational cohort study in a tertiary care teaching hospital. All patients required OLV after a left-sided double-lumen tube insertion during intubation. The definition of hypoxemia during OLV is a peripheral oxygen saturation (SpO2) value of less than 95%, while the inspired oxygen fraction (FiO2) is higher than 50% on a pulse oximetry device. ORi, pulse oximetry, PI, and PVI values were measured continuously. Sensitivity, specificity, positive and negative predictive values, likelihood ratios, and accuracy were calculated for ORi values equal to zero in different time points during surgery to predict hypoxemia. At Clinicaltrials.gov registry, the Registration ID is NCT05050552., Results: Hypoxemia was observed in 19 patients (38%). The accuracy for predicting hypoxemia during anesthesia induction at ORi value equals zero at 5 min after intubation in the supine position (DS5) showed a sensitivity of 92.3% (95% CI 84.9-99.6), specificity of 81.1% (95% CI 70.2-91.9), and an accuracy of 84.0% (95% CI 73.8-94.2). For predicting hypoxemia, ORi equals zero show good sensitivity, specificity, and statistical accuracy values for time points of DS5 until OLV30 where the sensitivity of 43.8%, specificity of 64%, and an accuracy of 56.1% were recorded. ORi and SpO2 correlation was found at DS5, 5 min after lateral position with two-lung ventilation (DL5) and at 10 min after OLV (OLV10) (p = 0.044, p = 0.039, p = 0.011, respectively). Time-dependent correlations also showed that; at a time point of DS5, ORi has a significant negative correlation with PI whereas, no correlations with PVI were noted., Conclusions: During the use of OLV for thoracic surgeries, from 5 min after intubation (DS5) up to 30 min after the start of OLV, ORi provides valuable information in predicting hypoxemia defined as SpO2 less than 95% on pulse oximeter at FiO2 higher than 50%., (© 2021. The Author(s).)

Background: Little is known about hypoxemia surrounding endotracheal intubation in the critically ill. Thus, we sought to identify risk factors associated with peri-intubation hypoxemia and its effects' on the critically ill., Methods: Data from a multicenter, prospective, cohort study enrolling 1,033 critically ill adults who underwent endotracheal intubation across 16 medical/surgical ICUs in the United States from July 2015-January 2017 were used to identify risk factors associated with peri-intubation hypoxemia and its effects on patient outcomes. We defined hypoxemia as any pulse oximetry ≤ 88% during and up to 30 minutes following endotracheal intubation., Results: In the full analysis (n = 1,033), 123 (11.9%) patients experienced the primary outcome. Five risk factors independently associated with our outcome were identified on multiple logistic regression: cardiac related reason for endotracheal intubation (OR 1.67, [95% CI 1.04, 2.69]); pre-intubation noninvasive ventilation (OR 1.66, [95% CI 1.09, 2.54]); emergency intubation (OR 1.65, [95% CI 1.06, 2.55]); moderate-severe difficult bag-mask ventilation (OR 2.68, [95% CI 1.72, 4.19]); and crystalloid administration within the preceding 24 hours (OR 1.24, [95% CI 1.07, 1.45]; per liter up to 4 liters). Higher baseline S p O 2 was found to be protective (OR 0.93, [95% CI 0.91, 0.96]; per percent up to 97%). Consistent results were seen in a separate analysis on only stable patients (n = 921, 93 [10.1%]) (those without baseline hypoxemia ≤ 88%). Peri-intubation hypoxemia was associated with in-hospital mortality (OR 2.40, [95% CI 1.33, 4.31]; stable patients: OR 2.67, [95% CI 1.38, 5.17]) but not ICU length of stay (point estimate 0.9 days, [95% CI -1.0, 2.8 days]; stable patients: point estimate 1.5 days, [95% CI -0.4, 3.4 days]) after adjusting for age, body mass index, illness severity, airway related reason for intubation (i.e., acute respiratory failure), and baseline S P O 2 ., Conclusions: Patients with pre-existing noninvasive ventilation and volume loading who were intubated emergently in the setting of hemodynamic compromise with bag-mask ventilation described as moderate-severe were at increased risk for peri-intubation hypoxemia. Higher baseline oxygenation was found to be protective against peri-intubation hypoxemia. Peri-intubation hypoxemia was associated with in-hospital mortality but not ICU length of stay., Trial Registration: Clinicaltrials.gov identifier: NCT02508948 and Registered Report Identifier: RR2-10.2196/11101.

Background: Hypoxemia frequently occurs during bronchoscopy. High-flow nasal cannula (HFNC) oxygen therapy may be a feasible alternative to prevent the deterioration of gas exchange during bronchoscopy. With the convenience of clinical use in mind, we modified an HFNC using a single cannula. This clinical trial was designed to test the hypothesis that a modified HFNC would decrease the proportion of patients with a single moment of peripheral arterial oxygen saturation (SpO 2 ) < 90% during bronchoscopy., Methods: In this single-center, prospective randomized controlled trial, hospitalized patients in the respiratory department in need of diagnostic bronchoscopy were randomly assigned to a modified HFNC oxygen therapy group or a conventional oxygen therapy (COT) group. The primary outcome was the proportion of patients with a single moment of SpO 2  < 90% during bronchoscopy., Results: Eight hundred and twelve patients were randomized to the modified HFNC (n = 406) or COT (n = 406) group. Twenty-four patients were unable to cooperate or comply with bronchoscopy. Thus, 788 patients were included in the analysis. The proportion of patients with a single moment of SpO 2  < 90% during bronchoscopy in the modified HFNC group was significantly lower than that in the COT group (12.5% vs. 28.8%, p < 0.001). There were no significant differences in the fraction of inspired oxygen between the two groups. The lowest SpO 2 during bronchoscopy and 5 min after bronchoscopy in the modified HFNC group was significantly higher than that in the COT group. Multivariate analysis showed that a baseline forced vital capacity (FVC) < 2.7 L (OR, 0.276; 95% CI, 0.083-0.919, p = 0.036) and a volume of fluid instilled > 60 ml (OR, 1.034; 95% CI, 1.002-1.067, p = 0.036) were independent risk factors for hypoxemia during bronchoscopy in the modified HFNC group., Conclusions: A modified HFNC could decrease the proportion of patients with a single moment of SpO 2  < 90% during bronchoscopy. A lower baseline FVC and large-volume bronchoalveolar lavage may predict desaturation during bronchoscopy when using a modified HFNC. Trial registration ClinicalTrials. Gov: NCT02606188. Registered 17 November 2015., (© 2021. The Author(s).)

Background: Limited evidence is available regarding the association between OSA and coronary plaque assessed by using quantitative coronary CT angiography., Research Question: Are there any associations between OSA severity-related indexes and the presence and burden of coronary plaque?, Study Design and Methods: Cross-sectional data from 692 patients who underwent sleep monitoring and coronary CT angiography were used for this study. Of these patients, 120 (17.3%) underwent polysomnography, and 572 (82.7%) underwent respiratory polygraphy. Multivariable logistic and linear regression analyses were used to investigate the associations of OSA severity-related indexes with the presence, volume, and composition of plaque., Results: In multivariable analyses, patients with moderate to severe OSA were more likely to have coronary plaques (P = .037), and plaques were more likely to contain a noncalcified plaque (NCP) component (P = .032) and a low-density NCP (LD NCP) component (P = .030). Furthermore, the apnea-hypopnea index and oxygen desaturation index as continuous variables were both associated with the presence of plaque, NCP, and LD NCP (all, P < .05). Multivariable linear regression models showed that moderate to severe OSA was associated with NCP volume (β = 50.328; P = .042) and LD NCP volume (β = 15.707; P = .011). Moreover, the apnea-hypopnea index (P = .015), oxygen desaturation index (P = .005), and percentage of nighttime with oxygen saturation < 90% (P = .017) were all significant predictors of LD NCP volume. Compared with those with no or mild OSA, patients with severe OSA had a significantly higher total plaque volume (P = .036), NCP volume (P = .036), and LD NCP volume (P = .013)., Interpretation: OSA was independently associated with the presence and burden of coronary plaque, which suggests an increased risk of coronary events., Clinical Trial Registration: Chinese Clinical Trial Registry; No. ChiCTR-ROC-17011027; http://chictr.org.cn., (Copyright © 2021 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Background and Aim: Whether long-term oxygen therapy (LTOT) improves survival in interstitial lung disease (ILD) is unclear. A recent study reported similar survival in ILD patients with severe hypoxemia on LTOT vs. moderate hypoxemia without LTOT, and proposed that LTOT could be indicated in ILD already at moderate hypoxemia. The aim of this study was to compare survival by severity of hypoxemia in patients with ILD and COPD, respectively, treated with LTOT., Methods: A population-based, longitudinal study of adults starting LTOT for ILD or COPD 1987-2018. Transplant-free survival was compared between moderate (PaO2 7.4-8.7 kPa) and severe (PaO2<7.4 kPa) hypoxemia using Cox regression, adjusted for age, sex, BMI, smoking status, WHO performance status, year of starting LTOT, diagnosis of heart failure, ischemic heart disease and diabetes mellitus., Results: In total, 17,084 patients were included, with ILD and moderate (n = 470) or severe hypoxemia (n = 2,408), and COPD with moderate (n = 2,087) or severe hypoxemia (n = 12,119). Compared with in COPD, ILD patients on LTOT had lower transplant-free survival after one year (41.9 vs. 67.1%) and two years (20.3 vs. 46.5%). In COPD worse hypoxemia was associated with slightly increased risk of death/lung transplantation, aHR 1.07 (1.00-1.14), a difference not shown in ILD, aHR 0.91 (0.80-1.03)., Conclusion: Transplant-free survival did not differ in ILD patients between moderate and severe hypoxia despite LTOT., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Hypoxemia is a cardinal feature of fibrotic interstitial lung disease (ILD). The incidence, progression, and prognostic significance of hypoxemia in patients with fibrotic ILD currently is unknown., Research Question: What are the epidemiologic features of hypoxemia and its additive prognostic value in a current risk prediction model of fibrotic ILD?, Methods: We identified 848 patients with fibrotic ILD (258 with idiopathic pulmonary fibrosis [IPF]) in five prospective ILD registries from Australia, Canada, and Switzerland. Cumulative incidence of exertional and resting hypoxemia from the time of diagnosis was estimated at 1-year intervals in patients with baseline 6-min walk tests, adjusted for competing risks of death and lung transplantation. Likelihood ratio tests were used to determine the prognostic significance of exertional and resting hypoxemia for 1-year mortality or transplantation when added to the ILD-GAP model. The cohort was divided into derivation and validation subsets to evaluate performance characteristics of the extended model (the ILD-GAP-O 2 model), which included oxygenation status as a predictor., Results: The 1-, 2-, and 5-year overall cumulative incidence was 6.1%, 17.3%, and 40.1%, respectively, for exertional hypoxemia and 2.4%, 5.6%, and 16.5%, respectively, for resting hypoxemia, which were significantly higher in patients with IPF compared with patients without IPF (P < .001 for both). Addition of exertional or resting hypoxemia to the ILD-GAP model improved 1-year mortality and transplantation prediction (P < .001 for both). The ILD-GAP-O 2 model showed improved discrimination (C-index, 0.80 vs 0.75) and model fit (Akaike information criteria, 400 vs 422) in the validation cohort, with comparable calibration., Interpretation: Patients with IPF have higher cumulative incidence of exertional and resting hypoxemia than patients without IPF. The extended ILD-GAP-O 2 model provides additional risk stratification for 1-year prognosis in fibrotic ILD., (Copyright © 2021 American College of Chest Physicians. All rights reserved.)

Gestational hypoxemia is often associated with reduced birth weight, yet how hypoxemia controls uteroplacental nutrient metabolism and supply to the fetus is unclear. This study tested the effects of maternal hypoxemia (HOX) between 0.8 and 0.9 gestation on uteroplacental nutrient metabolism and flux to the fetus in pregnant sheep. Despite hypoxemia, uteroplacental and fetal oxygen utilization and net glucose and lactate uptake rates were similar in HOX (n = 11) compared to CON (n = 7) groups. HOX fetuses had increased lactate and pyruvate concentrations and increased net pyruvate output to the utero-placenta. In the HOX group, uteroplacental flux of alanine to the fetus was decreased, as was glutamate flux from the fetus. HOX fetuses had increased alanine and decreased aspartate, serine, and glutamate concentrations. In HOX placental tissue, we identified hypoxic responses that should increase mitochondrial efficiency (decreased SDHB, increased COX4I2) and increase lactate production from pyruvate (increased LDHA protein and LDH activity, decreased LDHB and MPC2), both resembling metabolic reprogramming, but with evidence for decreased (PFK1, PKM2), rather than increased, glycolysis and AMPK phosphorylation. This supports a fetal-uteroplacental shuttle during sustained hypoxemia whereby uteroplacental tissues produce lactate as fuel for the fetus using pyruvate released from the fetus, rather than pyruvate produced from glucose in the placenta, given the absence of increased uteroplacental glucose uptake and glycolytic gene activation. Together, these results provide new mechanisms for how hypoxemia, independent of AMPK activation, regulates uteroplacental metabolism and nutrient allocation to the fetus, which allow the fetus to defend its oxidative metabolism and growth., (© 2021 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Purpose: Since 2010, new guidelines for procedural sedation and the Helsinki Declaration on Patient Safety have increased patient safety, comfort, and acceptance considerably. Nevertheless, the administration of sedatives and opioids during sedation procedures may put the patient at risk of hypoxemia. However, data on hypoxemia during procedural sedation are scarce. Here, we studied the incidence and severity of hypoxemia during procedural sedations in our hospital., Methods: A historical, single-centre cohort study was performed at the University Medical Centre Utrecht (UMCU), a tertiary centre in the Netherlands. Data from procedural sedation in our hospital between 1 January 2011 and 31 December 2018 (3,459 males and 2,534 females; total, 5,993) were extracted from our Anesthesia Information Management System. Hypoxemia was defined as peripheral oxygen saturation < 90% lasting at least two consecutive minutes. The severity of hypoxemia was calculated as area under the curve. The relationship between the severity of hypoxemia and body mass index (BMI), American Society of Anesthesiologists (ASA) Physical Status classification, and duration of the procedure was investigated. The primary outcome was the incidence of hypoxemia., Results: Twenty-nine percent of moderately to deeply sedated patients developed hypoxemia. A high incidence of hypoxemia was found in patients undergoing procedures in the heart catheterization room (54%) and in patients undergoing bronchoscopy procedures (56%). Hypoxemia primarily occurred in longer lasting procedures (> 120 min) and especially in the latter phases of the procedures. There was no relationship between severity of hypoxemia and BMI or ASA Physical Status., Conclusions: This study showed that a considerable number of patients are at risk of hypoxemia during procedural sedation with a positive correlation shown with increasing duration of medical procedures. Additional prospective research is needed to investigate the clinical consequences of this cumulative hypoxemia., (© 2021. The Author(s).)

Background: To investigate the indications for high-flow nasal cannula oxygen (HFNC) therapy in patients with hypoxemia during ventilator weaning and to explore the predictors of reintubation when treatment fails., Methods: Adult patients with hypoxemia weaning from mechanical ventilation were identified from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. The patients were assigned to the treatment group or control group according to whether they were receiving HFNC or non-invasive ventilation (NIV) after extubation. The 28-day mortality and 28-day reintubation rates were compared between the two groups after Propensity score matching (PSM). The predictor for reintubation was formulated according to the risk factors with the XGBoost algorithm. The areas under the receiver operating characteristic curve (AUC) was calculated for reintubation prediction according to values at 4 h after extubation, which was compared with the ratio of SpO 2 /FiO 2 to respiratory rate (ROX index)., Results: A total of 524,520 medical records were screened, and 801 patients with moderate or severe hypoxemia when undergoing mechanical ventilation weaning were included (100 < PaO2/FiO2 ≤ 300 mmHg), including 358 patients who received HFNC therapy after extubation in the treatment group. There were 315 patients with severe hypoxemia (100 < PaO2/FiO2 ≤ 200 mmHg) before extubation, and 190 patients remained in the treatment group with median oxygenation index 166[157,180] mmHg after PSM. There were no significant differences in the 28-day reintubation rate or 28-day mortality between the two groups with moderate or severe hypoxemia (all P > 0.05). Then HR/SpO 2 was formulated as a predictor for 48-h reintubation according to the important features predicting weaning failure. According to values at 4 h after extubation, the AUC of HR/SpO 2 was 0.657, which was larger than that of ROX index (0.583). When the HR/SpO 2 reached 1.2 at 4 h after extubation, the specificity for 48-h reintubation prediction was 93%., Conclusions: The treatment effect of HFNC therapy is not inferior to that of NIV, even on patients with oxygenation index from 160 to 180 mmHg when weaning from ventilator. HR/SpO 2 is more early and accurate in predicting HFNC failure than ROX index.

Background: To assess the relationship between the intrapulmonary shunt and PaO 2 /FiO 2 in severe hypoxemic patients after acute type A aortic dissection (ATAAD) surgery and to evaluate the effect of inhaled nitric oxide (iNO) on intrapulmonary shunt., Methods: Postoperative ATAAD patients with PaO 2 /FiO 2  ≤ 150 mmHg were enrolled. Intrapulmonary shunt was calculated from oxygen content of different sites (artery [CaO 2 ], mixed venous [CvO 2 ], and alveolar capillary [CcO 2 ]) using the Fick equation, where intrapulmonary shunt = (CcO 2 -CaO 2 )/(CcO 2 -CvO 2 ). Related variables were measured at baseline (positive end expiratory pressure [PEEP] 5 cm H 2 O), 30 min after increasing PEEP (PEEP 10 cm H 2 O), 30 min after 5 ppm iNO therapy (PEEP 10 cm H 2 O + iNO), and 30 min after decreasing PEEP (PEEP 5 cm H 2 O + iNO)., Results: A total of 20 patients were enrolled between April 2019 and December 2019. Intrapulmonary shunt and PaO 2 /FiO 2 were correlated in severe hypoxemic, postoperative ATAAD patients (adjusted R 2  = 0.467, p < 0.001). A mixed model for repeated measures revealed that iNO, rather than increasing PEEP, significantly decreased the intrapulmonary shunt (by 15% at a PEEP of 5 cm H 2 O and 16% at a PEEP of 10 cm H 2 O, p < 0.001 each) and increased PaO 2 /FiO 2 (by 63% at a PEEP of 5 cm H 2 O and 65% at a PEEP of 10 cm H 2 O, p < 0.001 each). After iNO therapy, the decrement of intrapulmonary shunt and the increment of PaO 2 /FiO 2 were also correlated (adjusted R 2  = 0.375, p < 0.001)., Conclusions: This study showed that intrapulmonary shunt and PaO 2 /FiO 2 were correlated in severe hypoxemic, postoperative ATAAD patients. Furthermore, iNO, rather than increasing PEEP, significantly decreased the intrapulmonary shunt to improve severe hypoxemic conditions., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Platypnea-orthodeoxia syndrome (POS) is a rare condition characterized by dyspnoea (platypnea) and arterial desaturation in the upright position resolved in the supine position (orthodeoxia). Intracardiac shunt, pulmonary ventilation-perfusion mismatch and others intrapulmonary abnormalities are involved., Case Presentation: We report a case of POS associated with two pathophysiological issues: one, cardiac POS caused by a patent foramen ovale (PFO) and second, pulmonary POS due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) interstitial pneumonia. POS has resolved after recovery of coronavirus disease 2019 (COVID-19) pneumonia., Conclusions: Right-to-left interatrial shunt and intrapulmonary shunt caused by SARS-CoV-2 pneumonia contributed to refractory hypoxemia and POS. Therefore, in case of COVID-19 patient with unexplained POS, the existence of PFO must be investigated.

Background: Supplemental oxygen is an essential treatment for childhood pneumonia but is often unavailable in low-resource settings or unreliable due to frequent and long-lasting power outages. We present a novel medium pressure reservoir (MPR) which delivers continuous oxygen to pediatric patients through power outages., Methods: An observational case series pilot study assessing the capacity, efficacy and user appraisal of a novel MPR device for use in low-resource pediatric wards. We designed and tested a MPR in a controlled preclinical setting, established feasibility of the device in two rural Kenyan hospitals, and sought user feedback and satisfaction using a standardized questionnaire., Results: Preclinical data showed that the MPR was capable of bridging power outages and delivering a continuous flow of oxygen to a simulated patient. The MPR was then deployed for clinical testing in nine pediatric patients at Ahero and Suba Hospitals. Power was unavailable for 2% of the total time observed due to 11 power outages (median 4.6 min, IQR 3.6-13.0 min) that occurred during treatment with the MPR. Oxygen flowrates remained constant across all 11 power outages. Feedback on the MPR was uniformly positive; all respondents indicated that the MPR was easy to use and provided clinically significant help to their patients., Conclusion: We present a MPR oxygen delivery device that has the potential to mitigate power insecurity and improve the standard of care for hypoxemic pediatric patients in resource-limited settings.

Abstract Breath-hold divers are known to develop cardiac autonomic changes and brady-arrthymias during prolonged breath-holding (BH). The effects of BH-induced hypoxemia were investigated upon both cardiac autonomic status and arrhythmogenesis by comparing breath-hold divers (BHDs) to non-divers (NDs). Eighteen participants (9 BHDs, 9 NDs) performed a maximal voluntary BH with face immersion. BHDs were asked to perform an additional BH at water surface to increase the degree of hypoxemia. Beat-to-beat changes in heart rate (HR), short-term fractal scaling exponent (DFAα1), the number of arrhythmic events [premature ventricular contractions (PVCs), premature atrial contractions (PACs)] and peripheral oxygen saturation (SpO 2 ) were recorded during and immediately following BH. The corrected QT-intervals (QTc) were analyzed pre- and post-acute BH. A regression-based model was used to split BH into a normoxic (NX) and a hypoxemic phase (HX). During the HX phase of BH, BHDs showed a progressive decrease in DFAα1 during BH with face immersion ( p  < 0.01) and BH with whole-body immersion ( p  < 0.01) whereas NDs did not ( p  > 0.05). In addition, BHDs had more arrhythmic events during the HX of BH with whole-body immersion when compared to the corresponding NX phase (5.9 ± 6.7 vs 0.4 ± 1.3; p  < 0.05; respectively). The number of PVCs was negatively correlated with SpO 2 during BH with whole-body immersion ( r  = -0.72; p  < 0.05). The hypoxemic stage of voluntary BH is concomitant with significant cardiac autonomic changes toward a synergistic sympathetic and parasympathetic stimulation. Co-activation led ultimately to increased bradycardic response and cardiac electrophysiological disturbances.

Patients treated with hemodialysis (HD) repeatedly undergo intradialytic low arterial oxygen saturation and low central venous oxygen saturation, reflecting an imbalance between upper body systemic oxygen supply and demand, which are associated with increased mortality. Abnormalities along the entire oxygen cascade, with impaired diffusive and convective oxygen transport, contribute to the reduced tissue oxygen supply. HD treatment impairs pulmonary gas exchange and reduces ventilatory drive, whereas ultrafiltration can reduce tissue perfusion due to a decline in cardiac output. In addition to these factors, capillary rarefaction and reduced mitochondrial efficacy can further affect the balance between cellular oxygen supply and demand. Whereas it has been convincingly demonstrated that a reduced perfusion of heart and brain during HD contributes to organ damage, the significance of systemic hypoxia remains uncertain, although it may contribute to oxidative stress, systemic inflammation, and accelerated senescence. These abnormalities along the oxygen cascade of patients treated with HD appear to be diametrically opposite to the situation in Tibetan highlanders and Sherpa, whose physiology adapted to the inescapable hypobaric hypoxia of their living environment over many generations. Their adaptation includes pulmonary, vascular, and metabolic alterations with enhanced capillary density, nitric oxide production, and mitochondrial efficacy without oxidative stress. Improving the tissue oxygen supply in patients treated with HD depends primarily on preventing hemodynamic instability by increasing dialysis time/frequency or prescribing cool dialysis. Whether dietary or pharmacological interventions, such as the administration of L-arginine, fermented food, nitrate, nuclear factor erythroid 2-related factor 2 agonists, or prolyl hydroxylase 2 inhibitors, improve clinical outcome in patients treated with HD warrants future research.