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Purpose: We investigated the effects of manipulating running velocity and hypoxic exposure on vastus lateralis muscle oxygenation levels during treadmill running. Methods: Eleven trained male distance runners performed 7 randomized runs at different velocities (8, 10, 12, 14, 16, 18, and 20 km·h−1), each lasting 45 seconds on an instrumented treadmill in normoxia (fraction of inspired oxygen [FiO2] = 20.9%), moderate hypoxia (FiO2 = 16.1%), high hypoxia (FiO2 = 14.1%), and severe hypoxia (FiO2 = 13.0%). Continuous assessment of Tissue Saturation Index (TSI) in the vastus lateralis muscle was conducted using near-infrared spectroscopy. Subsequently, changes in TSI (ΔTSI) data over the final 20 seconds of each run were compared between velocities and conditions. Results: There was a significant velocity × condition interaction for ΔTSI% (P <.001, η p 2 =.19), with a smaller ΔTSI% decline in normoxia compared with high hypoxia and severe hypoxia at 8 km·h−1 (g = 1.30 and 1.91, respectively), 10 km·h−1 (g = 0.75 and 1.43, respectively), and 12 km·h−1 (g = 1.47 and 1.95, respectively) (pooled values for all conditions: P <.037). The ΔTSI% decline increased with each subsequent velocity increment from 8 km·h−1 (−9.2% [3.7%]) to 20 km·h−1 (−22.5% [4.1%]) irrespective of hypoxia severity (pooled values for all conditions: P <.048). Conclusions: Running at slower velocities in conjunction with high and severe hypoxia reduces vastus lateralis muscle oxygenation levels. Muscle ΔTSI% proves to be a sensitive indicator, underscoring the potential use of near-infrared spectroscopy as a reference index of internal load during treadmill runs. [ABSTRACT FROM AUTHOR]

Purpose: We examined changes in stride temporal parameters and spring-mass model characteristics during repeated sprints following a 3-week period of "live high–train low and high" (LHTLH) altitude training in team-sport players. Methods: While residing under normobaric hypoxia (≥14 h/d; inspired oxygen fraction [FiO2] 14.5%–14.2%) for 14 days, elite field hockey players performed, in addition to their regular field hockey practice in normoxia, 6 sessions (4 × 5 × 5-s maximal sprints; 25-s passive recovery; 5-min rest) under either normobaric hypoxia (LHTLH; FiO2 ∼14.5%, n = 11) or normoxia (live high–train low; FiO2 20.9%, n = 12). A control group (live low–train low; FiO2 ∼20.9%, n = 9) residing in normoxia without additional repeated-sprint training was included. Before (Pre) and a few days (Post-1) and 3 weeks (Post-2) after the intervention, stride mechanics were assessed during an overground repeated-sprint test (8 × 20 m, 20-s recovery). Two-way repeated-measures analysis of variance (time [Pre, Post-1, and Post-2] × condition [LHTLH, live high–train low, and live low–train low]) were conducted. Results: Peak sprinting speed increased in LHTLH from Pre to Post-1 (+2.2% [2.0%]; P =.002) and Post-2 (+2.0% [2.4%]; P =.025), with no significant changes in live high–train low and live low–train low. There was no main effect of time (all P ≥.062), condition (all P ≥.771), or a significant time × condition interaction (all P ≥.230) for any stride temporal variable (contact time, flight time, stride frequency, and stride length) or spring-mass model characteristics (vertical and leg stiffness). Conclusions: Peak sprinting speed improved in elite field hockey players following LHTLH altitude training, while stride mechanical adjustments to repeated overground sprints remained unchanged for at least 3 weeks postintervention. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of repeated-sprint training with voluntary hypoventilation at low (RSH-VHL) and high (RS-VHH) lung volume on repeated-sprint ability (RSA) in female athletes. Methods: Over a 6-week period, 24 female soccer players completed 12 sessions of repeated 30-m running sprints with end-expiratory breath holding (RSH-VHL, n = 8), end-inspiratory breath holding (RS-VHH, n = 8), or unrestricted breathing (RS-URB, n = 8). Before and after training, a running RSA test consisting of performing 30-m all-out sprints until exhaustion was implemented. Results: From before to after training, the number of sprints completed during the RSA test was increased in both RSH-VHL (19.3 [0.9] vs 22.6 [0.9]; P <.01) and RS-VHH (19.3 [1.5] vs 20.5 [1.7]; P <.01) but not in RS-URB (19.4 [1.3] vs 19.5 [1.7]; P =.67). The mean velocity and the percentage decrement score calculated over sprints 1 to 17 were, respectively, higher (82.2% [1.8%] vs 84.6% [2.1%] of maximal velocity) and lower (23.7% [3.1%] vs 19.4% [3.2%]) in RSH-VHL (P <.01), whereas they remained unchanged in RS-VHH and RS-URB. The mean arterial oxygen saturation recorded during training at the end of the sprints was lower in RSH-VHL (92.1% [0.4%]) than in RS-VHH (97.3% [0.1%]) and RS-URB (97.8% [0.1%]). Conclusions: This study shows that female athletes can benefit from the RSH-VHL intervention to improve RSA. The performance gains may have been limited by the short sprinting distance with end-expiratory breath holding, which provoked only moderate hypoxemia. The increase in the number of sprints in RS-VHH seems to show that factors other than hypoxia may have played a role in RSA improvement. [ABSTRACT FROM AUTHOR]

Purpose: We examined the effects of increasing hypoxia severity on oxygenation kinetics in the vastus lateralis muscle during repeated treadmill sprints, using statistical parametric mapping (SPM). Methods: Ten physically active males completed 8 sprints of 5 seconds each (recovery = 25 s) on a motorized sprint treadmill in normoxia (sea level; inspired oxygen fraction = 0.21), moderate hypoxia (inspired oxygen fraction = 0.17), and severe hypoxia (SH; inspired oxygen fraction = 0.13). Continuous assessment of tissue saturation index (TSI) in the vastus lateralis muscle was conducted using near-infrared spectroscopy. Subsequently, TSI data were averaged for the sprint–recovery cycle of all sprints and compared between conditions. Results: The SPM analysis revealed no discernible difference in TSI signal amplitude between conditions during the actual 5-second sprint phase. However, during the latter portion of the 25-second recovery phase, TSI values were lower in SH compared with both sea level (from 22 to 30 s; P =.003) and moderate hypoxia (from 16 to 30 s; P =.001). The mean distance covered at sea level (22.9 [1.0] m) was greater than for both moderate hypoxia (22.5 [1.2] m; P =.045) and SH (22.3 [1.4] m; P =.043). Conclusions: The application of SPM demonstrated that only SH reduced muscle oxygenation levels during the late portion of the passive (recovery) phase and not the active (sprint) phase during repeated treadmill sprints. These findings underscore the usefulness of SPM for assessing muscle oxygenation differences due to hypoxic exposure and the importance of the duration of the between-sprints recovery period. [ABSTRACT FROM AUTHOR]

Background: Repeated exposure to heat (ie, plasma volume expansion) or altitude (ie, increase in total hemoglobin mass), in conjunction with exercise, induces hematological adaptations that enhance endurance performance in each respective environment. Recently, combining heat and altitude training has become increasingly common for athletes preparing to compete in temperate, sea-level conditions. Purpose: To review the physiological adaptations to training interventions combining thermal and hypoxic stimuli and summarize the implications for temperate, sea-level performance. Current Evidence: To date, research on combining heat and hypoxia has employed 2 main approaches: simultaneously combining the stressors during training or concurrently training in the heat and sleeping at altitude, sometimes with additional training in hypoxia. When environmental stimuli are combined in a training session, improvements in aerobic fitness and time-trial performance in temperate, sea-level conditions are generally similar in magnitude to those observed with heat, or altitude, training alone. Similarly, training in the heat and sleeping at altitude does not appear to provide any additional hematological or nonhematological benefits for temperate; sea-level performance relative to training in hot, hypoxic, or control conditions. Conclusions: Current research regarding combined heat and altitude interventions does not seem to indicate that it enhances temperate, sea-level performance to a greater extent than "traditional" (heat or hypoxia alone) training approaches. A major challenge in implementing combined-stressor approaches lies in the uncertainty surrounding the prescription of dosing regimens (ie, exercise and environmental stress). The potential benefits of conducting heat and altitude exposure sequentially (ie, one after the other) warrants further investigation. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate acute psychophysiological responses to repeated-sprint training in hypoxia (RSH) combined with whole-body cryotherapy (WBC). Method: Sixteen trained cyclists performed 3 sessions in randomized order: RSH, WBC-RSH (WBC pre-RSH), and RSH-WBC (WBC post-RSH). RSH consisted of 3 sets of 5 × 10-second sprints with 20-second recovery at a simulated altitude of 3000 m. Power output, muscle oxygenation (tissue saturation index), heart-rate variability, and recovery perception were analyzed. Sleep quality was assessed on the nights following test sessions and compared with a control night using nocturnal ActiGraphy and heart-rate variability. Results: Power output did not differ between the conditions (P =.27), while the decrease in tissue saturation index was reduced for WBC-RSH compared to RSH-WBC in the last set. In both conditions with WBC, the recovery perception was higher compared to RSH (WBC-RSH: +15.4%, and RSH-WBC: +21.9%, P <.05). The number of movements during the RSH-WBC night was significantly lower than for the control night (−18.7%, P <.01) and WBC-RSH (−14.9%, P <.05). RSH led to a higher root mean square of the successive differences of R-R intervals and high-frequency band during the first hour of sleep compared to the control night (P <.05) and RSH-WBC (P <.01). Conclusions: Inclusion of WBC in an RSH session did not modify the power output but could improve prolonged performance in hypoxia by maintaining muscle oxygenation. A single RSH session did not deteriorate sleep quality. WBC, particularly when performed after RSH, positively influenced recovery perception and sleep. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of cycling-based repeated-sprint training in hypoxia versus in normoxia on single overground running sprint performance and associated force–velocity (F–V) profile in world-class female rugby sevens players. Methods: Eighteen world-class female rugby sevens players were randomly assigned to repeated-sprint cycling training in normobaric hypoxia (n = 9) or normoxia (n = 9) groups. Training consisted of 4 sessions of repeated-sprint cycling training in normobaric hypoxia or in normoxia (4 × 5 × 5-s cycle sprints—25-s intersprint recovery performed in simulated altitude of ∼5000 m or in normoxia with 3-min interset rest in normoxia for both groups) in addition to rugby sevens training and strength and conditioning sessions within a 9-day intervention period before an international competition. Before and 1 day after the intervention, single 50-m overground running "all-out" sprint performance and associated F–V-related mechanical output were assessed. Results: No interaction (group × time; all P >.088), time effect (before vs 1 d after; all P >.296), or group effect (repeated-sprint cycling training in normobaric hypoxia vs in normoxia; all P >.325) was detected for 50-m overground running sprint performance and any derived F–V profiling variables. Conclusions: Four sessions of repeated-sprint training either in hypoxia or in normoxia performed over 9 days had no influence on single 50-m overground running sprint performance and associated F–V profile. In world-class female rugby sevens players, the intervention (training camp before an international competition) might have been too short to induce measurable changes. It is also plausible that implementing a similar program in players with likely different F–V profile may result in negligible mechanical effect. [ABSTRACT FROM AUTHOR]

Extracorporeal membrane oxygenator (ECMO) is a well-established therapy for respiratory failure. Refractory hypoxemia, despite the use of ECMO, remains a challenging problem. The ECMO circuit may not provide enough oxygenation support in the presence of high cardiac output, increased physiologic demand, and impaired gas exchange. Adding a second ECMO oxygenator using the same pump (sometimes needing a second drainage cannula) can improve oxygenation and facilitate lung-protective ventilation in selected patients. We describe a 3-patient series with severe ARDS secondary to SARS-CoV-2 infection and refractory hypoxemia during ECMO support successfully treated with this approach. [ABSTRACT FROM AUTHOR]

Introduction: Prone position ventilation (PPV) of patients with adult respiratory distress syndrome (ARDS) supported with veno-venous extracorporeal membrane oxygenation (V-V ECMO) may improve oxygenation and alveolar recruitment and is recommended when extensive dorsal consolidations are present, but only few data regarding adverse events (AE) related to PPV in this group of patients have been published. Methods: Nationwide retrospective analysis of 68 COVID-19 patients admitted from March 2020 – December 2021 with severe ARDS and need of V-V ECMO support. The number of patients treated with PPV, number of PPV-events, timing, the time spent in prone position, number and causes of AE are reported. Causes to stop the PPV regimen and risk factors for AE were explored. Results: 44 out of 68 patients were treated with PPV, and 220 PPV events are evaluated. AE were identified in 99 out of 220 (45%) PPV events and occurred among 31 patients (71%). 1 fatal PPV related AE was registered. Acute supination occurred in 19 events (9%). Causes to stop the PPV regimen were almost equally distributed between effect (weaned from ECMO), no effect, death (of other reasons) and AE. Frequent causes of AE were pressures sores and ulcers, hypoxia, airway related and ECMO circuit related. Most AE occurred during patients first or second PPV event. Conclusions: PPV treatment was found to carry a high incidence of PPV related AE in these patients. Causes and preventive measures to reduce occurrence of PPV related AE during V-V ECMO support need further exploration. [ABSTRACT FROM AUTHOR]

Background: Nasal obstruction in humans leads to mouth breathing and subsequent hypoxia in the entire body. Furthermore, nasal obstruction in growing children affects craniofacial growth and development. Objective: To investigate the effects of unilateral nasal obstruction (UNO) on craniofacial growth in mice of different ages, particularly on the morphology of the nasomaxillary complex and mandible. Methods: Mice aged 3, 6 and 12 weeks were selected as representatives of juvenile, adolescent and adult stages, respectively. A total of 30 male C57BL/6J mice (10 mice each at the ages of 3, 6 and 12 weeks) were used in this study for a 3‐week experiment. The mice in each age stage were randomly and evenly assigned to either the control group (C3+3, C6+3 and C12+3) or the experimental group (E3+3, E6+3 and E12+3). The UNO model in experimental group was constructed by plugging the mouse's left nostril, thereby disrupting its normal nasal breathing pattern and inducing hypoxia. The control group underwent the sham procedure. After 3 weeks, the length, width and height of the cranium, nasomaxillary complex and mandible of each group were measured on two‐dimensional images constructed by micro‐computed tomography. Furthermore, the impact of UNO on mouse growth was evaluated through the measurement of femoral length. Results: In juvenile mice, UNO inhibited the growth of cranial width, cranial height and mandibular length. In adolescent mice, UNO impeded the growth of the femoral length, cranial length, nasomaxillary length and mandibular length. In adult mice, no significant negative effects of UNO on craniofacial growth were found. Conclusion: Referring to the experimental results, in addition to actively treating nasal obstruction in patients, it is important to monitor the growth of the mandible in juveniles, as well as the nasomaxillary and mandibular growth in adolescents during orthodontic clinical practice. [ABSTRACT FROM AUTHOR]

Vital signs are an essential component of the emergency department (ED) assessment. Vital sign abnormalities are associated with adverse events in the ED setting and may indicate a risk of poor outcomes after ED discharge. What is the risk of adverse events among adult patients with abnormal vital signs at the time of ED discharge? Studies retrieved included 6 retrospective studies with adult patients discharged from the ED. These studies evaluated adverse outcomes in adult patients discharged from the ED with abnormal vital signs. Hypotension at discharge was associated with the highest odds of adverse events after discharge. Tachycardia was also a key predictor of adverse events after discharge and may be easily missed by ED clinicians. Based on the available evidence, the specific vital sign abnormality and the number of total abnormalities influence the risk of adverse outcomes after discharge. Vital sign abnormalities at the time of discharge also increase the risk of ED revisit. The most common abnormal vital sign at the time of discharge is tachycardia. [ABSTRACT FROM AUTHOR]

Recent evidence suggests that different hypoxic modalities might accelerate the rehabilitation process in injured athletes. In this review, the application of hypoxia during rehabilitation from musculoskeletal injury is explored in relation to two principles: (1) facilitating the healing of damaged tissue, and (2) mitigating detraining and inducing training adaptations with a reduced training load. Key literature that explores the underlying mechanisms for these themes is presented, and considerations for practice and future research directions are outlined. For principle (1), passive intermittent hypoxic exposures might accelerate tissue healing through angiogenic and osteogenic mechanisms. Experimental evidence is largely derived from rodent research, so further work is warranted to establish whether clinically meaningful effects can be observed in humans, before optimal protocols are determined (duration, frequency, and hypoxic severity). Regarding principle (2), a hypoxia-related increase in the cardiometabolic stimulus imposed by low-load exercise is appealing for load-compromised athletes. As rehabilitation progresses, a variety of hypoxic modalities can be implemented to enhance adaptation to energy-systems and resistance-based training, and more efficiently return the athlete to competition readiness. While hypoxic modalities seem promising for accelerating musculoskeletal injury rehabilitation in humans, and are already being widely used in practice, a significant gap remains regarding their evidence-based application. [ABSTRACT FROM AUTHOR]

\nSummary boxOver the past decade, numerous studies have investigated an innovative “live low-train high” approach based on the repetition of short (<30 s) “all-out” sprints with incomplete recoveries in hypoxia; the so-called Repeated-Sprint training in Hypoxia (RSH). The aims of the present review are therefore threefold. First, this study summarizes the available evidence on putative additional performance enhancement after RSH comparing to the same training in normoxia (RSN). Second, a critical analysis of underpinning mechanisms discusses how advantages can be obtained through RSH for sea-level performance enhancement. An enhanced microcirculatory vasodilation leading to improved muscle perfusion and/or oxygenation and an increase in muscular phosphocreatine content may help explain the superiority of RSH vs. RSN. Third, the present review aims to provide guidelines for coaches, athletes and scientists to apply RSH interventions with regard to the interval duration, exercise-to-rest ratio and training volume. In conclusion, this review supports repeated-sprint training in hypoxia as an efficient (but not magic) training intervention with 77% of the controlled studies reporting an additional benefit with added hypoxia, mainly for team-, combat- and racket-sports athletes but also for all other sports (e.g. endurance) that require repeated accelerations with lesser fatigue. This review critically analyzes the results of the studies involving repeated-sprint training in hypoxia (RSH) since 2013.10 years ago, RSH was proposed as a promising training strategy shown to delay muscle and metabolic fatigue, particularly during repeated-sprint exercises with incomplete recoveries.In the past decade, RSH has gained great popularity among athletes, coaches and scientists as an effective training reproduced in various sports with a large majority of studies reporting beneficial outcomes.RSH may improve performance in a fibre-type-selective and intensity-dependent manner, with mechanisms presumably different than those associated with other (less intense) hypoxic training methods.This review critically analyzes the results of the studies involving repeated-sprint training in hypoxia (RSH) since 2013.10 years ago, RSH was proposed as a promising training strategy shown to delay muscle and metabolic fatigue, particularly during repeated-sprint exercises with incomplete recoveries.In the past decade, RSH has gained great popularity among athletes, coaches and scientists as an effective training reproduced in various sports with a large majority of studies reporting beneficial outcomes.RSH may improve performance in a fibre-type-selective and intensity-dependent manner, with mechanisms presumably different than those associated with other (less intense) hypoxic training methods. [ABSTRACT FROM AUTHOR]

Oxygen production within human cells plays a critical role in cellular metabolism and is implicated in various diseases, including cancer. Investigating cellular heterogeneity under oxygen stimulation is crucial for elucidating disease mechanisms and advancing early therapeutic design. In this study, the platinum‐based wireless nanopore electrode (WNE) with a diameter of ≈200 nm is employed as a powerful tool to produce oxygen molecules near the cell nucleus. The oxygen production can be quantitatively controlled by adjusting the applied voltage. Through delivering oxygen near the cancer cell nucleus, this technique shows the capacity to alleviate the hypoxia microenvironment, a key factor in chemotherapy resistance. Furthermore, by modulating oxygen levels within individual living cells and delivering chemotherapeutic agents to the cancer cell nucleus, this approach offers significant potential for single‐cell manipulation and the investigation of cellular heterogeneity under oxygen stimulation. [ABSTRACT FROM AUTHOR]

Background: This narrative review was written by an expert panel to the members of the jury to help in the development of clinical practice guidelines on oxygen therapy. Results: According to the expert panel, acute hypoxemic respiratory failure was defined as PaO2 < 60 mm Hg or SpO2 < 90% on room air, or PaO2/FiO2 ≤ 300 mm Hg. Supplemental oxygen should be administered according to the monitoring of SpO2, with the aim at maintaining SpO2 above 92% and below 98%. Noninvasive respiratory supports are generally reserved for the most hypoxemic patients with the aim of relieving dyspnea. High-flow nasal cannula oxygen (HFNC) seems superior to conventional oxygen therapy (COT) as a means of avoiding intubation and may therefore be should probably be used as a first-line noninvasive respiratory support in patients requiring more than 6 L/min of oxygen or PaO2/FiO2 ≤ 200 mm Hg and a respiratory rate above 25 breaths/minute or clinical signs of respiratory distress, but with no benefits on mortality. Continuous positive airway pressure (CPAP) cannot currently be recommended as a first-line noninvasive respiratory support, since its beneficial effects on intubation remain uncertain. Despite older studies favoring noninvasive ventilation (NIV) over COT, recent clinical trials fail to show beneficial effects with NIV compared to HFNC. Therefore, there is no evidence to support the use of NIV or CPAP as first-line treatment if HFNC is available. Clinical trials do not support the hypothesis that noninvasive respiratory supports may lead to late intubation. The potential benefits of awake prone positioning on the risk of intubation in patients with COVID-19 cannot be extrapolated to patients with another etiology. Conclusions: Whereas oxygen supplementation should be initiated for patients with acute hypoxemic respiratory failure defined as PaO2 below 60 mm Hg or SpO2 < 90% on room air, HFNC should be the first-line noninvasive respiratory support in patients with PaO2/FiO2 ≤ 200 mm Hg with increased respiratory rate. Further studies are needed to assess the potential benefits of CPAP, NIV through a helmet and awake prone position in patients with acute hypoxemic respiratory failure not related to COVID-19. [ABSTRACT FROM AUTHOR]

Background: Solid tumors often develop hypoxic regions, leading to aggressive behavior and increased drug resistance. Methods: The chemical composition of Cymbopogon citratus essential oil (EO) was analyzed using GC-MS. Alginate nanoparticles containing the EO and its primary component, citral, were synthesized via the ionic gelation method. Encapsulation was confirmed using ATR-FTIR analysis. The anticancer efficacy of C. citratus EO, citral, and their respective alginate nanoparticles was evaluated under normoxic (21% oxygen) and hypoxic (1% oxygen) conditions on breast cancer (MDA-MB-231) and melanoma (A-375) cell lines. Additionally, qPCR and flow cytometry were used to assess apoptosis gene expression ratios (Bax/Bcl-2) and levels of apoptosis. Results: Citral (80.98%) was identified as the major component of the EO. Alginate nanoparticles containing C. citratus EO and citral (C. citratus-AlgNPs and citral-AlgNPs) were synthesized with particle sizes of 195 ± 4 nm and 222 ± 9 nm, and zeta potentials of -22 ± 3 mV and − 17 ± 1 mV, respectively. Both samples demonstrated significantly greater efficacy under hypoxic conditions. Citral and C. citratus-AlgNPs had IC50 values of 27 (19–39) µg/mL and 25 (4-147) µg/mL, respectively, against MDA-MB-231 and A-375 cells. Flow cytometry showed increased apoptosis under hypoxic conditions, with the highest rates observed for citral-AlgNPs and C. citratus-AlgNPs (84 ± 5 and 92 ± 5% in MDA-MB-231 and A-375 cells, respectively). Conclusion: This study demonstrates that alginate nanoparticles enhance the anticancer activity of C. citratus-AlgNPs and citral, particularly under hypoxic conditions, highlighting their potential for hypoxia-targeted cancer therapies. [ABSTRACT FROM AUTHOR]

The ocean has experienced substantial oxygen loss over recent decades, affecting marine ecosystems and fisheries. Investigating ocean deoxygenation during hyperthermal events, such as the Paleocene-Eocene Thermal Maximum (PETM), offers insights into its future dynamics. Here, sediment cores from the South Atlantic reveal a pronounced decline in foraminifera-bound δ15N, concurrent with an increase in marine barite δ34S and enhanced ocean productivity during the PETM. These findings suggest an expansion of oxygen-deficient zones (ODZs) from suboxia to anoxia in the thermocline, with ammonium and sulfide accumulation. Model simulations indicate "ammonium-type" ODZs were driven by Southern Ocean warming and elevated productivity. Intense fixed nitrogen loss at the upper boundary of these ODZs, along with increased oceanic phosphorus inventory, likely spurred a compensatory rise in N2 fixation. While the Pacific might experience different oxygenation conditions during the PETM, parts of the Atlantic thermocline became anoxic, highlighting potential spatial variabilities of ocean deoxygenation under global warming. Extreme warming 56 million years ago may have rendered parts of the subsurface Atlantic Ocean anoxic and toxic to fish due to ammonium and hydrogen sulfide accumulation – a scenario we must strive to prevent under current anthropogenic climate change. [ABSTRACT FROM AUTHOR]

Air-breathing fish risk losing aerially sourced oxygen to ambient hypoxic water since oxygenated blood from the air-breathing organ returns through the heart to the branchial basket before distribution. This loss is thought to help drive the evolutionary reduction in gill size with the advent of air-breathing. In many teleost fish, gill size is known to be highly plastic by modulation of their anatomic diffusion factor (ADF) with inter-lamellar cell mass (ILCM). In the anoxia-tolerant crucian carp, ILCM recedes with hypoxia but regrows in anoxia. The air-breathing teleost Chitala ornata has been shown to increase gill ADF from normoxic to mildly hypoxic water by reducing ILCM. Here, we test the hypothesis that ADF is modulated to minimize oxygen loss in severe aquatic hypoxia by measuring ADF, gas-exchange, and by using computed tomography scans to reveal possible trans-branchial shunt vessels. Contrary to our hypothesis, ADF does not modulate to prevent oxygen loss and despite no evident trans-branchial shunting, C. ornata loses only 3% of its aerially sourced O2 while still excreting 79% of its CO2 production to the severely hypoxic water. We propose this is achieved by ventilatory control and by compensating the minor oxygen loss by extra aerial O2 uptake. [ABSTRACT FROM AUTHOR]

Plant quiescence and seed dormancy can be triggered by reduced oxygen availability. Under water, oxygen depletion caused by flooding can culminate in a quiescent state, which is a plant strategy for energy preservation and survival. In adult plants, a quiescent state can be activated by sugar starvation, leading to metabolic depression. In seeds, secondary dormancy can be activated by reduced oxygen availability, which creates an unfavourable state for germination. The physical dormancy of some seeds and buds includes barriers to external conditions, which indirectly results in hypoxia. The molecular processes that support seed dormancy and plant survival through quiescence under hypoxia include the N-degron pathway, which enables the modulation of ethylene-responsive factors of group VII and downstream targets. This oxygen- and nitric oxide-dependent mechanism interacts with phytohormone-related pathways to control growth. [ABSTRACT FROM AUTHOR]

Objective: This letter to the editor presents suggestions for the therapeutic use of riboflavin in perinatal brain lesions caused by oxygen deprivation.Methods: Clinical and preclinical studies using riboflavin conjugated with other components for the treatment of cerebral oxygen deprivation were included in the discussion.Results: Oxygen deprivation is predisposed by anoxia, hypoxia, or ischemia and causes severe early central damage, including sensorimotor impairment. At the moment, these lesions lack effective and affordable therapies. We present studies demonstrating the neuroprotective effects of riboflavin–containing drugs to treat children affected by hypoxic perinatal injuries.Discussion: This article suggests conducting preclinical studies to elucidate the potential isolated effects of riboflavin on the pathogenesis of perinatal brain injury caused by oxygen deprivation, by presenting routes for future clinical strategies for the prevention or treatment of perinatal encephalopathies. [ABSTRACT FROM AUTHOR]

Aim Methods Results Conclusions The aim of this study was to compare patients referred to our retrieval service who were palliated before transfer, versus those transferred who were palliated within 7 days of birth.We conducted a retrospective chart review of infants referred to our neonatal retrieval service between 1 December 2015 and 31 March 2022 who died during retrieval or within 7 days of referral. Demographic and clinical data were collected from the service database and electronic medical records.Data on 60 infants were analysed; 25 (42%) infants were not transported and were palliated at the referring hospital, 35 (58%) infants were transported and later palliated at the accepting hospital. The most common primary diagnoses were prematurity (42%) and hypoxemic ischemic encephalopathy (HIE) (42%). Infants palliated at the referring hospital were more likely than those transported and later palliated to require resuscitation including chest compressions (52% vs. 23%, P = 0.02), management for hypotension (72% vs. 20%, P < 0.001) and management for pneumothorax (28% vs. 0%, P = 0.001) and less likely to require management for seizures (8% vs. 43%, P = 0.003).Palliation at the referring hospital should be considered as an option when escalating care is predicted to not affect outcome. In this cohort the infants least likely to be transported required significant management during stabilisation. Determining the infants for whom transport is non‐beneficial remains difficult. [ABSTRACT FROM AUTHOR]

Background: Interatrial right-to-left shunt flow through a patent foramen ovale (PFO) can be caused by changes in heart position for anastomosis during off-pump coronary artery bypass (OPCAB). We herein present a case in which the direction of PFO shunt flow changed with heart position during OPCAB and the ventilation settings after sternal closure. Case presentation: A 66-year-old man with interstitial pneumonia underwent OPCAB. Preoperative transesophageal echocardiography revealed right-to-left shunt flow through a PFO induced by the Valsalva maneuver. During OPCAB, heart displacement resulted in right-to-left shunting and acute hypoxemia, which quickly improved with increase of inspired oxygen fraction. After chest closure, bidirectional shunt flow developed under increased airway pressure. Conclusions: Vigilant intraoperative monitoring with TEE and postoperative airway pressure management are important to address shunt flow and hypoxemia due to PFO. [ABSTRACT FROM AUTHOR]

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, TNFa, CXCL8, ISG15, IFIT1, RIGI, IFNb, CCL5, and CXCL10) was quantified using quantitative RT-PCR. The outcome variable was having severe hypoxemia (SpO2 = 90%). The association analysis was performed using a volcano plot, adjusted logistic regression, and orthogonal partial least squares discriminant analysis (OPLSDA). We found that 26 of 121 children had severe hypoxemia (SpO2 = 90%). CXCL8 was overexpressed [fold changes (FC) > 2; q-value < 0.05], and ISG15, IFIT1, RIGI, IFNb, 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. [ABSTRACT FROM AUTHOR]

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 SpO2 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/m2 and 51 patients with BMI > 40 kg/m2 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 SpO2 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 SpO2 values at the end of preoxygenation, beginning of intubation, beginning of the ORi alarm, when SpO2 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% SpO2 was observed as 32 s in morbidly obese patients and 94 s in patients with a normal body mass index. The SpO2 alert period was determined as time difference between 97% and 95% SpO2. The data were recorded as 15 s and 36 s, respectively. It was observed that tolerable apnea, ORiⓇ, SpO2 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 PaO2. Clinical trials. gov identifier: NCT05480748 registered 2022-07-29. [ABSTRACT FROM AUTHOR]

A fundamental question in evolutionary biology concerns the relative contributions of phenotypic plasticity vs. local adaptation (genotypic specialization) in enabling wide-ranging species to inhabit diverse environmental conditions. Here, we conduct a long-term hypoxia acclimation experiment to assess the relative roles of local adaptation and plasticity in enabling highland and lowland deer mice (Peromyscus maniculatus) to sustain aerobic thermogenesis at progressively increasing elevations. We assessed the relative physiological performance capacities of highland and lowland natives as they were exposed to progressive, stepwise increases in hypoxia, simulating the gradual ascent from sea level to an elevation of 6,000 m. The final elevation of 6,000 m far exceeds the highest attainable elevations within the species' range, and therefore tests the animals' ability to tolerate levels of hypoxia that surpass the prevailing conditions within their current distributional limits. Our results demonstrate that highland natives exhibit superior thermogenic capacities at the most severe levels of hypoxia, suggesting that the species' broad fundamental niche and its ability to inhabit such a broad range of elevational zones is attributable to genetically based local adaptation, including evolved changes in plasticity. Transcriptomic and physiological measurements identify evolved changes in the acclimation response to hypoxia that contribute to the enhanced thermogenic capacity of highland natives. [ABSTRACT FROM AUTHOR]

Aim Methods Results Conclusion To investigate if tachypneic response to hypoxia is decreased in older patients.We included all patients ≥65 years of age attending 52 Spanish emergency departments (EDs) for whom peripheral arterial oxygen saturation (SatO2) measured by pulsioxymetry and respiratory rate (RR) were registered at ED arrival. We assessed the relationship between SatO2 and RR in different models, and with the best‐fitting model, we independently analyzed this relationship in four subgroups according to patient age (65–69, 70–79, 80–89, and ≥90 years). Five sensitivity analyses using different subsets of patients were carried out to check for the consistency of the results.We included 7126 patients, with medians for SatO2 and RR of 97% (interquartile range [IQR]: 94–98) and 15 bpm (IQR: 15–16), respectively. We found significant associations (P < 0.001) between SatO2 and RR in every model tested (P < 0.001 for all), with the quadratic model obtaining the best fit (R2: 0.098) over those obtained with linear (R2: 0.096) and logarithmic (R2: 0.092) models. The same was observed in sensitivity analyses, with R2 for quadratic models ranging from 0.069 in patients with low comorbidity and 0.102 in patients breathing room air. The mean RR for 100% SatO2 was 15 bpm and increased as SatO2 decreased, although with a progressive slowing of the slope, with a mean RR of 27 at 50% SatO2. We detected a decreased RR response to increasing hypoxemia according to age and, while the RR curve was higher and with a progressively steepening slope in the 972 patients aged 65–69 (mean RR of 42 bpm with 50% SatO2), a progressive slowing of slope was observed in the 2693 patients aged 70–79 (mean RR of 28 with 50% SatO2), the 2582 aged 80–89 (mean RR of 25) and the 879 aged ≥90 (mean RR of 23). Sensitivity analyses provided very similar results.Tachypneic response to hypoxemia in older patients decreases as age advances, regardless of the reason leading to hypoxemia. Geriatr Gerontol Int 2024; ••: ••–••. [ABSTRACT FROM AUTHOR]

Viscosity and hypoxia, as microenvironment parameters, play important roles in maintaining normal biological processes and homeostasis. Therefore, simultaneous and sensitive detection of these elements with simple and effective methods could offer precise information in biology. Here, we report a two-site lysosome-targeting fluorescent probe, NVP, for monitoring viscosity and nitroreductase with dual emission channels (emission shift is 86 nm). The NVP probe has displayed highly sensitive and selective responses towards viscosity and nitroreductase, respectively. Significantly, the fluctuations of viscosity and NTR have been detected in vitro and in vivo. We expect that the dual-responsive fluorescent NVP probe will become a potential molecular tool for the exploration of deeper functions of viscosity and hypoxia. [ABSTRACT FROM AUTHOR]

Background: Sigh breaths may impact outcomes in acute hypoxemic respiratory failure (AHRF) during assisted mechanical ventilation. We investigated whether sigh breaths may impact mortality in predefined subgroups of patients enrolled in the PROTECTION multicenter clinical trial according to: 1.the physiological response in oxygenation to Sigh (responders versus non-responders) and 2.the set levels of positive end-expiratory pressure (PEEP) (High vs. Low-PEEP). If mortality differed between Sigh and No Sigh, we explored physiological daily differences at 7-days. Results: Patients were randomized to pressure support ventilation (PSV) with Sigh (Sigh group) versus PSV with no sigh (No Sigh group). (1) Sighs were not associated with differences in 28-day mortality in responders to baseline sigh-test. Contrarily-in non-responders-56 patients were randomized to Sigh (55%) and 28-day mortality was lower with sighs (17%vs.36%, log-rank p = 0.031). (2) In patients with PEEP > 8cmH2O no difference in mortality was observed with sighs. With Low-PEEP, 54 patients were randomized to Sigh (48%). Mortality at 28-day was reduced in patients randomised to sighs (13%vs.31%, log-rank p = 0.021). These findings were robust to multivariable adjustments. Tidal volume, respiratory rate and ventilatory ratio decreased with Sigh as compared with No Sigh at 7-days. Ventilatory ratio was associated with mortality and successful extubation in both non-responders and Low-PEEP. Conclusions: Addition of Sigh to PSV could reduce mortality in AHRF non-responder to Sigh and exposed to Low-PEEP. Results in non-responders were not expected. Findings in the low PEEP group may indicate that insufficient PEEP was used or that Low PEEP may be used with Sigh. Sigh may reduce mortality by decreasing physiologic dead space and ventilation intensity and/or optimizing ventilation/perfusion mismatch. Clinical Trial Registration: ClinicalTrials.gov; Identifier: NCT03201263. [ABSTRACT FROM AUTHOR]

Background: As a supportive treatment, the effectiveness of oxygen therapy in ischemic stroke (IS) patients remains unclear. This study aimed to evaluate the relationships between arterial partial pressure of oxygen (PaO2) and both consciousness at discharge and all-cause mortality risk in ICU IS patients. Methods: Blood gas measurements for all patients diagnosed with IS were extracted from the MIMIC-IV database. Patients were classified into four groups based on their average PaO2 during the first ICU day: hypoxemia (PaO2 < 80 mmHg), normoxemia (PaO2 80–120 mmHg), mild hyperoxemia (PaO2 121–199 mmHg), and moderate/severe hyperoxemia (PaO2 ≥ 200 mmHg). The primary endpoint was 90-day all-cause mortality. Secondary outcomes included the level of consciousness at discharge, assessed by the Glasgow Coma Scale (GCS), and 30-day all-cause mortality. Multivariate Cox regression and Restricted cubic spline (RCS) analysis were used to investigate the relationship between mean PaO2 and mortality, and to assess the nonlinear association between exposure and outcomes. Results: This study included a total of 946 IS patients. The cumulative incidence of 30-day and 90-day all-cause mortality increased with decreasing PaO2 levels. RCS analysis revealed a nonlinear relationship between PaO2 and the risk of 30-day all-cause mortality (nonlinear P < 0.0001, overall P < 0.0001), as well as a nonlinear association between PaO2 and 90-day all-cause mortality (nonlinear P < 0.0001, overall P < 0.0001). The results remained consistent after excluding the small subset of patients who received reperfusion therapy. Sensitivity analysis indicated that the favorable impact on survival tends to increase with the extended duration of elevated PaO2. Conclusions: For IS patients who do not receive reperfusion therapy or whose recanalization status is unknown, a lower PaO2 early during ICU admission is considered an independent risk factor for short-term and recent mortality. Adjusting respiratory parameters to maintain supraphysiological levels of PaO2 appears to be beneficial for survival, although this finding requires further validation through additional studies. Trial registration: Not applicable. [ABSTRACT FROM AUTHOR]

To address the issue of the traditional fish hypoxia detection methods, which have low accuracy and require a lot of labor, a Prune-YOLOv5s-based hypoxia risk assessment method for farmed fish is proposed. This paper introduces a hypoxia risk assessment method for cultured fish based on the Prune - YOLOv5s algorithm. This method first collects data on aquatic surface respiration (ASR) performed by fish under hypoxic conditions to create a data set for fish hypoxia. The dataset is then utilized to train the YOLOv5s model. Then, the lightweight and improved YOLOv5s model was used to monitor the behavior of fish surface respiration during hypoxia in real-time. The introduction of the ASR coefficient allows for quantifying ASR instances in fish, which indicates hypoxia risk. The fish hypoxia assessment module is designed to evaluate the risk of hypoxia. The improved performance of the YOLOv5s model before and after modifications and the accuracy of the fish hypoxia assessment module are tested through the fish hypoxia experiment. The test results show that compared with the YOLOv5s model, the detection accuracy, model size, inference speed, and detection speed of the PruneYOLOv5s model have been significantly improved. Among them, the detection accuracy of the 65% Prune YOLOv5s model, which has the best comprehensive performance, has been increased by 0.6% compared with the original model. The size of the model is reduced to 45. 3% of the original model. The inference speed is improved by 23.8%, and the detection speed is enhanced by 31.4%. The fish hypoxia assessment method achieves 97.4% accuracy in the test set of 39 test videos and performs well in the hypoxia cycle experiment. The research indicates that the Prune-YOLOv5s-based hypoxia risk assessment method for cultured fish can effectively detect hypoxic conditions and provide accurate risk alerts, showing high feasibility for practical application. [ABSTRACT FROM AUTHOR]

Simple Summary: Pancreatic cancer is surrounded by a dense fibrotic environment due to the activity of pancreatic stellate cells (PSCs). This hinders the effectiveness of treatment by limiting drug penetration and oxygen delivery. To better understand this, PSCs and cancer cells were studied in laboratory models using radiotracer imaging techniques. The results indicated that while glucose uptake and hypoxia were similar between cancer cells alone and in combination with PSCs, a specific marker of fibrosis (FAPα) was significantly higher in PSC-rich environments. In mice, the marker in question decreased in tumors with only PSCs, indicating that the cells had died. Conversely, the biomarker increased over time in tumors containing both cancer cells and PSCs, suggesting that mouse cells had invaded. This study sheds light on how the tumor environment influences metabolism and thus provides insights for more targeted theranostic applications. In turn, this approach supports the development of more reliable models. Background/Objective Pancreatic stellate cells (PSCs) in pancreatic adenocarcinoma (PDAC) are producing extracellular matrix, which promotes the formation of a dense fibrotic microenvironment. This makes PDAC a highly heterogeneous tumor-stroma-driven entity, associated with reduced perfusion, limited oxygen supply, high interstitial fluid pressure, and limited bioavailability of therapeutic agents. Methods In this study, spheroid and tumor xenograft models of human PSCs and PanC-1 cells were characterized radiopharmacologically using a combined positron emission tomography (PET) radiotracer approach. [18F]FDG, [18F]FMISO, and [18F]FAPI-74 were employed to monitor metabolic activity, hypoxic metabolic state, and functional expression of fibroblast activation protein alpha (FAPα), a marker of activated PSCs. Results In vitro, PanC-1 and multi-cellular tumor spheroids demonstrated comparable glucose uptake and hypoxia, whereas FAPα expression was significantly higher in PSC spheroids. In vivo, glucose uptake as well as the transition to hypoxia were comparable in PanC-1 and multi-cellular xenograft models. In mice injected with PSCs, FAPα expression decreased over a period of four weeks post-injection, which was attributed to the successive death of PSCs. In contrast, FAPα expression increased in both PanC-1 and multi-cellular xenograft models over time due to invasion of mouse fibroblasts. Conclusion The presented models are suitable for subsequently characterizing stromal cell-induced metabolic changes in tumors using noninvasive molecular imaging techniques. [ABSTRACT FROM AUTHOR]

Simple Summary: Exogenous ketone esters (KEs) are compounds that elevate blood ketones without dietary restriction and they show promise as anti-cancer agents. This study examined the effects of an exogenous ketone ester-supplemented (eKET) diet in mouse models of metastatic breast and kidney cancers. Our eKET diet slowed tumor growth and reduced metastatic spread to the lungs in both cancer types. The mechanisms behind these effects differed: the eKET diet downregulated genes involved in Wnt and TGFβ signaling in mammary cancers, whereas it downregulated genes related to hypoxia and DNA damage repair in tumor-bearing kidneys. The diet was safe for use overall but was associated with some negative physiological effects in mice with renal cancer. Thus, eKET diets could be an effective addition to current cancer treatments, but additional work is needed to fully understand their limitations. Background/Objectives: Ketone esters (KEs) exhibit promise as anti-cancer agents but their impact on spontaneous metastases remains poorly understood. Although consumption of a ketogenic diet (KD) that is low in carbohydrates and high in fats can lead to KE production in vivo, the restrictive composition of KDs may diminish adherence in cancer patients. Methods: We investigated the effects of an exogenous ketone ester-supplemented (eKET), carbohydrate-replete diet on tumor growth, metastasis, and underlying mechanisms in orthotopic models of metastatic breast (4T1-Luc) and renal (Renca-Luc) carcinomas. Mice were randomized to diet after tumor challenge. Results: Administration of KEs did not alter tumor cell growth in vitro. However, in mice, our eKET diet increased circulating β-hydroxybutyrate and inhibited primary tumor growth and lung metastasis in both models. Body composition analysis illustrated the overall safety of eKET diet use, although it was associated with a loss of fat mass in mice with renal tumors. Immunogenetic profiling revealed divergent intratumoral eKET-related changes by tumor type. In mammary tumors, Wnt and TGFβ pathways were downregulated, whereas in renal tumors, genes related to hypoxia and DNA damage repair were downregulated. Conclusions: Thus, our eKET diet exerts potent antitumor and antimetastatic effects in both breast and renal cancer models, albeit with different modes of action and physiologic effects. Its potential as an adjuvant dietary approach for patients with diverse cancer types should be explored further. [ABSTRACT FROM AUTHOR]

Hypoxia in preterm infants is a clinical condition that has been associated with cognitive and behavioral disturbances for which treatment strategies are strongly required. Melatonin administration following brain insults has been considered a promising therapeutic strategy due to its antioxidant and anti‐inflammatory effects. Not surprisingly, it has been extensively studied for preventing disturbances following brain injury. This study evaluated the effects of melatonin on developmental disturbances, memory disruption, and hippocampal cell loss induced by neonatal anoxia in rats. Neonatal Wistar rats were subjected to anoxia and subsequently treated with melatonin. Later, maturation of physical characteristics, ontogeny of reflexes, learning and memory in the Morris water maze (MWM), and estimates of the number of hippocampal neurons, were evaluated. Melatonin treatment attenuated (1) female anoxia‐induced delay in superior incisor eruption, (2) female anoxia‐induced vibrissae placement reflexes, and (3) male and female anoxia‐induced hippocampal neuronal loss. Melatonin also promoted an increase (5) in swimming speeds in the MWM. In addition, PCA analysis showed positive associations between the acoustic startle, auditory canal open, and free fall righting parameters and negative associations between the male vehicle anoxia group and the male melatonin anoxia group. Therefore, melatonin treatment attenuates both anoxia‐induced developmental deficits and hippocampal neuronal loss. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

A 71-year-old man with a history of recurrent tonsillar squamous cell carcinoma was admitted to the hospital with oropharyngeal bleeding. He received high-dose radiation therapy with curative intent. On day 4 of hospitalization, he demonstrated hypoxia resulting from an airway mucus plug and was brought to the medical ICU. [ABSTRACT FROM AUTHOR]

Deep water running (DWR) is an exercise model often used for health promotion purposes. This study standardized an aerobic capacity evaluation protocol specific for attached DWR in young healthy adults and monitored a DWR session with normobaric hypoxia exposure addition. In study 1, nine young healthy adults, seven male and two female (22.88 ± 3.14 years old; 72.44 ± 11.38 kg; 174.88 ± 9 cm; 23.58 ± 2.33 kg m−2), were subjected to two DWR incremental tests with a 48-hour interval between them, and in study 2, six healthy males were subjected to three (hypoxia, normoxia, and inter-effort recovery hypoxia) attached DWR exercise sessions involving normobaric hypoxia. Data are expressed as average ± standard deviation. Friedman's test was used to compare the groups with a significance level of P < 0.05. In study 1, no significant statistical differences were observed for the physiological variables analyzed. In study 2, there was no difference in strength and lactate between conditions; values of rates of perceived exertion were higher in the hypoxic session, compared to inter-effort recovery hypoxia, in efforts 1 and 5, respectively, while heart rate was lower in effort 1 in normoxia. In hypoxia, effort 1 was lower than effort 3, with no alteration in recovery hypoxia. This aerobic capacity evaluation protocol is valid, sensitive, and replicable, and there were no important differences in the physiological variables from high-intensity exercise sessions monitoring in hypoxia, normoxia, and inter-effort recovery hypoxia conditions. [ABSTRACT FROM AUTHOR]

Measuring tissue oxygen concentration is crucial in understanding the pathophysiological process of hypoxia in head and neck cancer (HNC) and its significant role in cancer biology. This study aimed to determine the feasibility of T1 mapping using a variable flip angle (VFA) technique with stack of stars (SOS) trajectory sampling in HNC patients undergoing chemoradiotherapy (CRT). To evaluate the ability of SOS acquisition to detect T1, a phantom study was conducted and compared to conventional Cartesian acquisition (CART). Additionally, four newly diagnosed patients were recruited and underwent two scans each at baseline and inter-treatment. The repeatability of SOS and CART acquisitions was assessed by comparing the T1 measurements of CSF from the baseline and intra-treatment MRI studies. The changes in ∆T1 of the tumors during air and oxygen inhalation between baseline and inter-treatment scans were also evaluated. Our study found that the 3D VFA SOS sequence was effective in reducing motion artifacts compared to the conventional VFA sequence with CART sampling and the same scan time, as demonstrated by the results from the phantom and patient studies. In terms of repeatability, no significant correlation was observed between the variability in ΔT1 measurements of CSF obtained from SOS T1 maps. The SOS ΔT1 measurements showed higher consistency, as evidenced by the ICC values ranging from 0.52 to 0.92. The ∆T1 measurements on the primary tumors increased after the first CRT (p<0.05) for all patients who showed a positive treatment response, except for one patient (0.05

The article discusses research which evaluated the effect of helmet continuous positive airway pressure (CPAP) on tidal volume assessed by bioelectrical impedance. The study analyzed the variation in respiratory parameters including tidal volumes, breathing frequency and minute ventilation before helmet application and after helmet CPAP application. Results of arterial blood gas analysis, respiratory and hemodynamics parameters are presented.

BACKGROUND: The flow reaching the vocal folds may be lower than that at the output of high-flow nasal cannula (HFNC) system. This could be due to upper-respiratory obstruction, oxygen leakage, or other factors. The objective of this study was to observe the effect of flow through a nasopharyngeal airway on intrapharyngeal pressure (IPP) in subjects undergoing fiberoptic bronchoscopy (FOB). METHODS: Patients scheduled for FOB were invited to participate. Measurements were performed at flows of 0-60 L/min; the subjects wore WN-N95 folding medical protective masks (N95) and either underwent FOB or not. IPP at each flow was recorded following 15 s of ventilation, and the cross-sectional area (CSA) of the gastric sinus was measured before and after FOB. Hypoxemia, reflux aspiration, and other pertinent events were recorded. RESULTS: Sixty subjects undergoing FOB at the Affiliated Hospital of Jiaxing University participated in this trial from October 2022-September 2023. IPP increased significantly with an increase in flow and also increased after placing the N95 mask with the same flow (P < .001). When results from before to after FOB were compared, the difference in CSA was statistically significant 263.6 (220.7-300.5) mm² vs 305.5 (275.4-329.5) mm², P < .001, but the difference in the risk of reflux aspiration was not statistically significant (0% vs 6.7%, P = .13). Complication rates during treatment were 8.3% for hypoxemia, 0% for reflux aspiration, 1.7% for hypertension, 1.7% for hypotension, 6.7% for tachycardia, 5% for bradycardia, and 10% for postoperative nausea and vomiting. CONCLUSIONS: HFNC can provide effective oxygen therapy for people undergoing FOB, and increases in IPP with flow in the range of 0-60 L/min may not increase the risk of reflux aspiration. [ABSTRACT FROM AUTHOR]

Introduction: Hypoxic respiratory failure occurs when the respiratory system cannot adequately provide oxygen to the body, leading to hypoxemia. High-flow nasal cannula (HFNC) improved the survival rate among patients with acute hypoxic respiratory failure. Due to physiological alterations, pregnancy can exacerbate distal renal tubular acidosis (dRTA). Pregnancy complicated by hypokalemic periodic paralysis (HPP) poses significant risks due to the potential cardiac and respiratory failure related to low potassium levels. Case description: A woman, 21 years old, pregnant with her first child at 33-34 weeks gestation came with complaints of shortness of breath one day before admission. Complaints accompanied by cramps in both legs. On the second day, the respiratory rate (RR) suddenly increased to 35x/min, and oxygen saturation (SpO2) was 95% on a non-rebreathing mask (NRM) at 15 l/min. The patient was transferred to the Intensive Care Unit (ICU) with a diagnosis of primigravida at 33-34 weeks, respiratory failure, HPP, suspected dRTA, severe metabolic acidosis, sepsis, and urinary tract infection (UTI). She was given O2 via HFNC at flow 40 l/min and a fraction of inspired oxygen (FiO2) 66%. Improvement was seen on the 4th day; the patient's shortness of breath was reduced with HFNC, and the patient's motor strength improved. Conclusion: The use of HFNC showed a positive outcome and was proven to have been successful in treating hypoxic respiratory failure in pregnant women. Respiratory muscle weakness and severe metabolic acidosis caused by dRTA and HPP cannot be cleared due to the limited settings in rural areas. Furthermore, the assessment and management of HPP and dRTA are still limited in many hospitals in remote areas of Indonesia. [ABSTRACT FROM AUTHOR]

The article presents a case study of unresolved pneumonia in a 43-year-old male admitted to the ICU due to an endobronchial mass obstructing the left main bronchus. Typically, patients with community-acquired pneumonia show improvement within 3-5 days; however, persistent symptoms or radiologic infiltrates indicate non-resolving pneumonia, necessitating the ruling out of alternative diagnoses such as tuberculosis or cancer, and assessment of treatment efficacy and patient compliance.

Objective: Obstructive sleep apnea (OSA) has been associated with an elevated cardiovascular risk, increased daytime sleepiness, cognitive decline, and slower electroencephalographic activity (EEG). This study assesses EEG patterns during wakefulness in OSA patients compared to those without sleep-disordered breathing. Materials and methods: This retrospective study analyzed 30 OSA patients with an Apnea/Hypopnea Index (AHI) of 15 or higher, as well as 29 individuals without sleep-disordered breathing (AHI of 5 or lower) who underwent hospital polysomnography and met all inclusion criteria. Sociodemographic and EEG data were obtained from the sleep laboratory database. Blinded EEG analysis was conducted by two observers, assessing activity in the frontal, central, and occipital regions. Results: No significant differences were observed in EEG activity between OSA and non-OSA patients. However, a weak correlation was found between decreased C3 EEG frequency and higher AHI (p = 0.033), as well as increased total sleep time and higher O2 EEG frequency (p = 0.038). Lower amplitudes in C3 (p = 0.043) and O1 (p = 0.031) were correlated with reduced average oxygen saturation. Conclusion: Our findings suggest that OSA-related hypoxemia may impact neuronal activity, highlighting the need to address this sleep-disordered breathing in order to potentially prevent the cognitive decline observed in OSA patients. [ABSTRACT FROM AUTHOR]

Background: Previous studies have reported the link between hypoxic conditions and NLRP3 inflammasome-mediated pulpal inflammation in the progression of pulpitis. However, the underlying mechanism has not been fully elucidated. This study aimed to investigate the role of HIF-1α in the regulation of NLRP3 inflammasome pathway via NF-κB signaling under hypoxic conditions with or without LPS in human dental pulp fibroblasts (HDPFs) during the progression of pulpitis. Methods: HIF-1α plasmids or siRNAs were used to upregulate or downregulate HIF-1α in HDPFs, respectively. The effect of hypoxia with or without LPS on the NF-κB signaling and NLRP3 inflammasome pathway was analyzed by immunofluorescence staining, qRT-PCR, western blotting and ELISA. Results: The hypoxic conditions alone induced ASC oligomerization and NLRP3/CASP1 inflammasome pathway activation via NF-κB signaling in a time-dependent manner in HDPFs. The upregulation of HIF-1α further promoted hypoxia-induced ASC oligomerization and NLRP3/CASP1 inflammasome pathway activation via NF-κB signaling compared to the hypoxia-induced group. In comparison, downregulation of HIF-1α inhibited ASC oligomerization and NLRP3/CASP1 inflammasome pathway activation via NF-κB signaling compared to the hypoxia-induced group. Additionally, LPS plus hypoxia further promoted HIF-1α expression and NLRP3/ASC/CASP1 inflammasome pathway activation via NF-κB signaling compared to the hypoxia-induced group. Conclusions: HIF-1α served as a positive regulator of NLRP3/ASC/CASP1 inflammasome pathway activation via NF-κB signaling in HDPFs in the sterile pulpal inflammation and caries-related pulpitis microenvironment. The finding of a novel functional HIF-1α-NF-κB-NLRP3 axis provides insight into the link between the hypoxic microenvironment and pulpal inflammation, thus supporting a promising therapeutic strategy for the control of pulpal inflammation. [ABSTRACT FROM AUTHOR]

Generating highly organized skeletal muscle tissues that mimics the cellular alignment, maturation, and contraction of native skeletal muscle remains a challenge in disease modeling and regenerative therapies. Existing methodologies are constrained by complexity in fabrication and difficulty in achieving aligned 3D myofibers. Here, a functional skeletal muscle organoid‐on‐a‐chip (SMO) is engineered by establishing mechanical boundary constraints at either end of the cell‐laden extracellular matrix hydrogel within polydimethylsiloxane microstructures to promote the formation of an anisotropic biophysical microenvironment in tissues. The linearly aligned tissue, featuring multinucleated myofibers with distinct cross‐striations, exhibited a positive force‐frequency relationship and stable calcium transients under electrical stimulation. SMOs applicability is demonstrated by systematically evaluating muscle response to varying degrees of intermittent hypoxia. Murine‐ or human‐derived SMOs revealed that, with increasing hypoxia severity, muscles transitioned from a compensatory phase‐characterized by enhanced contractile function, vacuolation and hypertrophic‐like changes in myofibers, fiber type switching, and metabolic shift, to a decompensatory stage, paralleling in vivo muscle responses and highlighting interspecies differences. Human‐derived SMOs are also utilized to assess self‐repair capabilities and pharmaceuticals protective effects on damaged muscle. Together, the platform, with its simplicity of operation and reliable phenotypic readouts, demonstrates significant potential for future disease modeling and regenerative therapies. [ABSTRACT FROM AUTHOR]

Hypoxia (low-oxygen) is one of the most common characteristics of solid tumours. Exploiting tumour hypoxia to reductively activate Pt(IV) prodrugs has the potential to deliver toxic Pt(II) selectively and thus overcome the systemic toxicity issues of traditional Pt(II) therapies. However, our current understanding of the behaviour of Pt(IV) prodrugs in hypoxia is limited. Here, we evaluated and compared the aryl carbamate fluorogenic Pt(IV) complexes, CisNap and CarboNap, as well as the previously reported OxaliNap, as potential hypoxia-activated Pt(IV) (HAPt) prodrugs. Low intracellular oxygen concentrations (<0.1%) induced the greatest changes in the respective fluorescence emission channels. However, no correlation between reduction under hypoxic conditions and toxicity was observed, except in the case for CarboNap, which displayed significant hypoxia-dependent toxicity. Other aryl carbamate Pt(IV) derivatives (including non-fluorescent analogues) mirrored these observations, where carboplatin(IV) derivative CarboPhen displayed a hypoxia-selective cytotoxicity similar to that of CarboNap. These findings underscore the need to perform extensive structure activity relationship studies on the cytotoxicity of Pt(IV) complexes under normoxic and hypoxic conditions. [ABSTRACT FROM AUTHOR]

BACKGROUND Long-term oxygen supplementation for at least 15 hours per day prolongs survival among patients with severe hypoxemia. On the basis of a nonrandomized comparison, long-term oxygen therapy has been recommended to be used for 24 hours per day, a more burdensome regimen. METHODS To test the hypothesis that long-term oxygen therapy used for 24 hours per day does not result in a lower risk of hospitalization or death at 1 year than therapy for 15 hours per day, we conducted a multicenter, registry-based, randomized, controlled trial involving patients who were starting oxygen therapy for chronic, severe hypoxemia at rest. The patients were randomly assigned to receive long-term oxygen therapy for 24 or 15 hours per day. The primary outcome, assessed in a time-to-event analysis, was a composite of hospitalization or death from any cause within 1 year. Secondary outcomes included the individual components of the primary outcome assessed at 3 and 12 months. RESULTS Between May 18, 2018, and April 4, 2022, a total of 241 patients were randomly assigned to receive long-term oxygen therapy for 24 hours per day (117 patients) or 15 hours per day (124 patients). No patient was lost to follow-up. At 12 months, the median patient-reported daily duration of oxygen therapy was 24.0 hours (interquartile range, 21.0 to 24.0) in the 24-hour group and 15.0 hours (interquartile range, 15.0 to 16.0) in the 15-hour group. The risk of hospitalization or death within 1 year in the 24-hour group was not lower than that in the 15-hour group (mean rate, 124.7 and 124.5 events per 100 person-years, respectively; hazard ratio, 0.99; 95% confidence interval [CI], 0.72 to 1.36; 90% CI, 0.76 to 1.29; P=0.007 for nonsuperiority). The groups did not differ substantially in the incidence of hospitalization for any cause, death from any cause, or adverse events. CONCLUSIONS Among patients with severe hypoxemia, long-term oxygen therapy used for 24 hours per day did not result in a lower risk of hospitalization or death within 1 year than therapy for 15 hours per day. [ABSTRACT FROM AUTHOR]

Simple Summary: Head and neck squamous cell carcinoma (HNSC) is the most common type of cancer in the head and neck region, affecting areas like the mouth and throat. Understanding how these cancers grow and spread is crucial for developing better treatments. This study focuses on a group of proteins called solute carrier (SLC) transporters, which help cancer cells survive and grow by moving nutrients and other molecules in and out of cells. We investigated the levels of these transporters in cancerous tissues compared to normal tissues and found that certain SLC transporters are much more active in tumors. These transporters are linked to worse outcomes for patients. By targeting these specific transporters with new drugs, we hope to create more effective treatments that can block cancer growth and improve survival rates for patients with HNSC. Background: Head and neck squamous cell carcinoma (HNSC) is the most prevalent cancer in the head and neck region, originating from the mucosal epithelium of the oral cavity, pharynx, and larynx. The solute carrier (SLC) transporter superfamily, consisting of over 400 proteins across 65 families, plays a crucial role in cellular functions and presents promising targets in precision oncology. This study aims to analyze the expression of SLC transporters in HNSC and their potential as biomarkers and therapeutic targets. Methods: We leveraged mRNA and protein expression data from The Cancer Genome Atlas (TCGA) and The Human Protein Atlas (HPA) to examine SLC transporter expression in HNSC. Gene Set Enrichment Analysis (GSEA) was conducted to assess the involvement of SLC transporters in various oncogenic pathways. Results: Significant upregulation of SLC transporters was observed in tumor tissues compared to normal tissues, with notable increases in SLC16A3, SLC53A1, SLC25A32, and SLC2A3. This upregulation correlated with poorer overall survival (OS) and disease-specific survival (DSS). GSEA revealed that these transporters are significantly involved in critical oncogenic pathways, including epithelial-mesenchymal transition (EMT), angiogenesis, and hypoxia, which are vital for cancer progression and metastasis. Conclusions: The study identifies SLC transporters as potential biomarkers and therapeutic targets in HNSC. Targeting these transporters with small molecule inhibitors could disrupt essential supply routes for cancer cells, enhancing treatment efficacy and improving patient outcomes. This study paves the way for developing SLC-based target therapies in precision oncology, with the goal of improving survival rates for patients with HNSC. [ABSTRACT FROM AUTHOR]

Endoscopic retrograde cholangiopancreatography (ERCP) is an important endoscopic technology in the field of digestive endoscopy. It is mainly used to diagnose biliary diseases in the early stage, and now it has developed into the diagnosis and treatment of biliary and pancreatic diseases. Compared with the general endoscopic treatment, its operation time is longer and its anesthesia risk is greater. ERCP under sedation/anesthesia can enhance patients′ tolerance and create better diagnosis and treatment conditions for digestive endoscopists, but there is also the risk of anesthesia-related hypoxemia, so airway management during operation is particularly important. In this paper, the ventilation strategies of ERCP patients under sedation/anesthesia were reviewed in combination with the related research in recent years. [ABSTRACT FROM AUTHOR]

Iron‐rich, ferruginous waters were the dominant geochemical regime for most of Earth's history. Modern ferruginous waters are found in stratified, sulfur‐poor lakes, and serve as crucial analogs for biogeochemical cycling throughout Earth's past. Here we present the first depth‐resolved data of physical structure, nutrients and trace elements from Lake Poso (Indonesia), a deep oligotrophic ancient lake. Lake Poso is ferruginous, with anoxia below ~ 90 m depth, placing it among the world's largest ferruginous lakes. Physical stratification is weaker than other tropical anoxic lakes, indicating sensitivity for paleoclimate reconstructions. Trace elements and nutrients are predominantly shaped by the oxic–anoxic transition. Manganese– and Fe oxyhydroxide–driven biogeochemical cycling occurs at distinct depth horizons, with Co and Ni controlled by Mn and showing shallow release in anoxic waters, while V, Cr, P, and As are controlled by Fe, with release in surface sediments and diffusive transport. Chromium is nonquantitatively removed in anoxic waters, in contrast to widespread assumptions in Cr‐based paleoreconstructions. Oxycline U and Se removal corresponds to a local N minimum, suggesting biological reduction and/or uptake. These first ferruginous water Se data also show removal in sediments, indicating sediment signals reflect multiple removal processes and informing Se‐based paleoreconstructions, while the absence of sediment U removal contrasts other anoxic basins. A comparison with other ferruginous lakes demonstrates how local influences drive deviations from expectations in other systems, and highlight common, generalizable ferruginous basin features. Therefore, these data will guide research in ferruginous settings across space and time, and improve paleoreconstructions from ferruginous sediment records. [ABSTRACT FROM AUTHOR]

Background/Objectives: The present study examined the effect of 12-week combined exercise training in normobaric hypoxia on arterial stiffness, inflammatory biomarkers, and red blood cell (RBC) hemorheological function in 24 obese older women (mean age: 67.96 ± 0.96 years). Methods: Subjects were randomly divided into two groups (normoxia (NMX; n = 12) and hypoxia (HPX; n = 12)). Both groups performed aerobic and resistance exercise training programs three times per week for 12 weeks, and the HPX group performed exercise programs in hypoxic environment chambers during the intervention period. Body composition was estimated using bioelectrical impedance analysis equipment. Arterial stiffness was measured using an automatic waveform analyzer. Biomarkers of inflammation and oxygen transport (tumor necrosis factor alpha, interleukin 6 (IL-6), erythropoietin (EPO), and vascular endothelial growth factor (VEGF)), and RBC hemorheological parameters (RBC deformability and aggregation) were analyzed. Results: All variables showed significantly more beneficial changes in the HPX group than in the NMX group during the intervention. The combined exercise training in normobaric hypoxia significantly reduced blood pressure (systolic blood pressure: p < 0.001, diastolic blood pressure: p < 0.001, mean arterial pressure: p < 0.001, pulse pressure: p < 0.05) and brachial–ankle pulse wave velocity (p < 0.001). IL-6 was significantly lower in the HPX group than in the NMX group post-test (p < 0.001). Also, EPO (p < 0.01) and VEGF (p < 0.01) were significantly higher in the HPX group than in the NMX group post-test. Both groups showed significantly improved RBC deformability (RBC EI_3Pa) (p < 0.001) and aggregation (RBC AI_3Pa) (p < 0.001). Conclusions: The present study suggests that combined exercise training in normobaric hypoxia can improve inflammatory biomarkers and RBC hemorheological parameters in obese older women and may help prevent cardiovascular diseases. [ABSTRACT FROM AUTHOR]