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Background: SpO2 is a widely used estimation of oxygen saturation owing to its convenient usage and low cost. However, SpO2 determination under low perfusion condition is severely affected by noise.Methods: In this paper, an autocorrelation modeling method for the oxygen saturation measurement during low perfusion is presented. The proposed method mainly contains two steps: calculating the autocorrelation of the photoplethysmography (PPG) signals and modeling for the parameter calculation. The autocorrelation of the PPG signals can suppress the noise and extract pulse waves from low perfusion signals. The model can realize the calculation of SpO2 with the autocorrelation signals. Results: Experiments showed that the new method had a good accuracy and stability under low perfusion condition (perfusion index (PI)

Continuous and mobile monitoring of vital signs may soon become a reality on hospital wards. By enabling the early detection of clinical deterioration, it may improve quality of care and patient safety.

Objectives Determine if chronic rhinosinusitis (CRS) is associated with systemic hypoxemia. Methods Outpatient otolaryngology visits for 12 months were analyzed, identifying patients with a diagnosis of CRS, without a comorbid diagnosis of pulmonary disease, and an oxygen saturation measurement within 14 days of the otolaryngology visit. Oxygen saturation (SpO2) measures (average SpO2, minimum SpO2 and proportion abnormal SpO2) were compared between CRS patients (with nasal polyps [NP] and without NP) and a control cohort of otology patients, also without pulmonary disease with univariate and multivariate analysis. Results Among 640 unique CRS patients with 3105 encounters, the mean and minimum SpO2 measurements were 97.6% (97.5%‐97.7%) and 97.3% (97.2%‐97.5%), respectively. Among 3613 control patients with 25 073 encounters, the mean and minimum SpO2 measurements were 97.3% (97.3%‐97.4%) and 97.1% (97.1%‐97.2%), respectively. When comparing mean and minimum SpO2 among CRSsNP (97.5% and 97.2%), CRScNP (97.3% and 97.0%) and control patients (97.3% and 97.1%), no statistically significant differences were found among the 3 groups in mean and minimum SpO2 adjusting for age and sex (P = .183 and P = .464, respectively, ANOVA). With respect to the presence of an abnormally low oxygen saturation (SpO2 ≤ 94%), 4.4% of the CRSsNP, 10.9% of the CRScNP and 7.3% of the control patients demonstrated a low oxygen saturation (P = .013). Conclusion CRS alone does not objectively contribute to systemic hypoxemia, although a subset of CRScNP patients may have abnormally low SpO2, possibly warranting SpO2 assessment in this group of patients. Level of evidence 3.

Background Suboptimal tissue perfusion and oxygenation during surgery may be responsible for postoperative nausea and vomiting in some patients. This trial tested the hypothesis that muscular tissue oxygen saturation–guided intraoperative care reduces postoperative nausea and vomiting. Methods This multicenter, pragmatic, patient- and assessor-blinded randomized controlled (1:1 ratio) trial was conducted from September 2018 to June 2019 at six teaching hospitals in four different cities in China. Nonsmoking women, 18 to 65 yr old, and having elective laparoscopic surgery involving hysterectomy (n = 800) were randomly assigned to receive either intraoperative muscular tissue oxygen saturation–guided care or usual care. The goal was to maintain muscular tissue oxygen saturation, measured at flank and on forearm, greater than baseline or 70%, whichever was higher. The primary outcome was 24-h postoperative nausea and vomiting. Secondary outcomes included nausea severity, quality of recovery, and 30-day morbidity and mortality. Results Of the 800 randomized patients (median age, 50 yr [range, 27 to 65]), 799 were assessed for the primary outcome. The below-goal muscular tissue oxygen saturation area under the curve was significantly smaller in patients receiving muscular tissue oxygen saturation–guided care (n = 400) than in those receiving usual care (n = 399; flank, 50 vs. 140% · min, P < 0.001; forearm, 53 vs. 245% · min, P < 0.001). The incidences of 24-h postoperative nausea and vomiting were 32% (127 of 400) in the muscular tissue oxygen saturation–guided care group and 36% (142 of 399) in the usual care group, which were not significantly different (risk ratio, 0.89; 95% CI, 0.73 to 1.08; P = 0.251). There were no significant between-group differences for secondary outcomes. No harm was observed throughout the study. Conclusions In a relatively young and healthy female patient population, personalized, goal-directed, muscular tissue oxygen saturation–guided intraoperative care is effective in treating decreased muscular tissue oxygen saturation but does not reduce the incidence of 24-h posthysterectomy nausea and vomiting. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

The incidence of retinopathy of prematurity (ROP) is showing an increasing trend in the United States. This may be because of increasing survival rates among extremely preterm infants (

Purpose: To inform about possible use of the automatic retinal oximetry for the retinal oxygen saturation measurement in the eye and systemic diseases. Methods: We performed a literature review dealing with issues of retinal oxygen saturation monitoring by dual non-invasive retinal oximetry Oxymap T1 (Oxymap ehf. Reykjavík, Iceland). Results: We have found two main strains writing our paper on retinal oxygen saturation eye diseases. The first section concerns diseases created by having hypoxia as its main pathological factor - for example diabetes mellitus and retinal vein occlusion. The second group deals with atrophy as the main pathological mechanism which is typical for decreasing retinal oxygen consumption – for example glaucoma or retinitis pigmentosa (the second one named is not included in our work). Oximetry in systemic diseases creates a relatively new chapter of this branch with a very big potential of interdisciplinary cooperation for the future. It is possible the cooperation will not only include diabetologists but also neurologists (for example, in diseases like sclerosis multiplex or Devic‘s, Alzheimer‘s and Parkinson‘s disease) and haematologists (retinal oxygen saturation changes in patients with different rheological attributes of blood). Conclusion: Retinal oxygen saturation measuring by automatic retinal oximetry is a relatively new method with scientifically confirmed high reproducibility of results. Currently it is the only experimental method with vast potentials not only in the realm of the possibility of observing eye diseases (diabetic retinopathy, retinal vein occlusion or glaucoma) but also in developing interdisciplinary cooperation with diabetologists, neurologists and haematologists.

Background COVID-19 exerts deleterious cardiopulmonary effects, leading to worse prognosis in the most effected. Purpose The aim of this retrospective multi-center observational cohort study was to analyze the trajectories of key advanced hemodynamic parameters amongst hospitalized COVID-19 patients according to different risk populations using a chest-patch wearable providing continuous remote patient monitoring. Methods The study was conducted in five COVID-19 isolation units. Patients admitted to the units were connected to a photoplethysmography based noninvasive remote advanced hemodynamic monitor after completing a basic risk factor survey. Physiological parameters were measured every 15 minutes during the hospitalization, including cardiac output (CO), cardiac index (CI), systemic vascular resistance (SVR), heart rate, blood pressure (BP), respiratory rate, blood oxygen saturation (SpO2), and body temperature. Results 492 COVID-19 patients (179 females, average age 58.7 years) were included in the final analysis, with more than 3 million measurements collected during an average of 75.3 hours. Overall, within the first five days of hospitalizations we found a significant increase in SVR, and a significant decrease in SpO2, DBP, CO and CI (p Conclusions This is the first comprehensive continuous advanced hemodynamic profiling of COVID-19 patients. Worse hemodynamic status was prominent in high risk populations. Funding Acknowledgement Type of funding sources: None.

A multiwavelength photoacoustic remote sensing (PARS) microscope is combined with swept-source optical coherence tomography and applied to in-vivo, non-contact retinal imaging. Building on the proven strength of multiwavelength PARS imaging, the system is applied for estimating retinal oxygen saturation in the rat eye. The capability of the technology is demonstrated by imaging both microanatomy and the microvasculature of the retina in-vivo. To our knowledge, this is the first time a non-contact photoacoustic imaging technique is employed for in-vivo oxygen saturation measurement in the retina.

Oxygen saturation (StO 2 ) measurement allows to detect different clinical conditions related with the low oxygenation of tissues or is used to monitor the quality and safety of organ transplantation. This study is focused on the visualization and measurement of StO 2 using hyperspectral imaging (HSI) through non-contact skin captures, targeting a potential real-time monitoring application. A customized acquisition system composed by a hyperspectral camera (covering the 470-900 nm spectral range) and a thermal camera was developed to capture images of hands in a non-contact fashion. An experimental procedure was established to measure the evolution of StO 2 in healthy hands where a compression of the index finger or brachial artery were performed. StO 2 measurements were performed in normal, compression, and reperfusion states. Two mathematical models with different sets of wavelengths were evaluated. The results show the proposed models, which employed two wavelengths (660 and 880 nm), obtain reliable StO 2 values, providing a potential non-contact imaging tool for StO 2 measurement.

Oxygen is commonly used in the delivery room during neonatal resuscitation. The transition from intrauterine to extrauterine life is a challenge to newborns, and exposure to too much oxygen can cause an increase in oxidative stress. The goal of resuscitation is to achieve normal oxygen levels as quickly as possible while avoiding excessive oxygen exposure and preventing inadequate oxygen supplementation. Although it has been shown that room air resuscitation is as effective as using 100% oxygen, often preterm infants need some degree of oxygen supplementation. The ideal concentration of oxygen with which to initiate resuscitation is yet to be determined. Current delivery room resuscitation guidelines recommend the use of room air for term newborns and preterm newborns of greater than or equal to 35 weeks' gestation and the use of a fraction of inspired oxygen of 0.21 to 0.3 for preterm infants of less than 35 weeks' gestation. Further recommendations include titrating oxygen supplementation as needed to obtain goal saturations. However, there is no current consensus on an intermediate oxygen concentration to start resuscitation or goal range saturations for preterm and asphyxiated term infants.

The article presents selected issues related to the construction of a microprocessor pulse-oximeter. Pulse oximeters are non invasive medical devices that monitor level of the oxygen saturation of the splanchnic blood. The proposed principle of the system’s operation, presented in the paper, was implemented in the device constructed and tested in a laboratory. The selected results of laboratory examination of the proposed system are presented in the paper. It is potentially possible to implement this method of the oxygen saturation measurement to the contemporary textiles and intelligent clothes. The result of the laboratory examination of the exemplary patient is presented and it proofs proper operation of the proposed device. Selected issues related with proper implementation of the proposed device in the intelligent clothes are described and a proper solution of the potential problems is proposed.

Background and Aims Patients on haemodialysis (HD) suffer a very high rate of cardiovascular mortality with some evidence suggesting a possible association with decreasing blood oxygen saturation (SO2) during sessions. The ratio between arterial SO2 (SaO2) and central venous SO2 (ScvO2) or Oxygen Extraction Ratio (OER), which represents an estimate of the amount of oxygen claimed by peripheral tissues and of the haemodialysis related hypoxic stress, might represent a new prognostic factor. Method We evaluate the relationship between OER values and mortality risks in HD patients in a prospective multicentre observational study. We enrolled chronic HD patients with permanent central venous catheter (CVC) and no fistula, in whom ScvO2 measurement is at hand and SaO2 is available with a peripheral oxymeter. OER ([(SaO2−ScvO2)/SaO2]×100) was measured before and after HD at enrolment (HD OER sessions) in each patients, and a one-year follow-up was planned to record the number of deaths. Results In 101 patients (age 71.5 ± 14 years on dialysis for 47 ± 38 months), during 9 ± 6 months of follow up, we recorded 35 deaths. Patients were then divided into two groups, above or below the median value of pre-HD OER, which was 30%. In these groups, the average incidence of deaths was 12% (24 deaths) and 5,5% (11 deaths) respectively (p Conclusion Patients with pre-HD OER > 30% have a higher mortality risk, most probably secondary to reduced capability to respond to HD related oxygen requirements. OER is novel biomarker to identify patients at greatest clinical risk.

PURPOSE. Recent evidence suggests that the smaller retinal vessels are significantly involved in the regulation of retinal blood flow and that this regulation may differ among the macular area and the retinal periphery. An alternative to studying blood flow regulation in smaller retinal vessels that are difficult to resolve is to assess the metabolic consequences of changes in the microcirculation using oximetry. METHODS. In 20 normal persons aged (mean ± SD, range) 30.1 ± 3.8 (24-37) years, the oxygen saturation and diameter of retinal arterioles and venules to the macular area and the retinal periphery were studied before and during an increase in the arterial blood pressure induced by isometric exercise. RESULTS. The isometric exercise increased the mean arterial blood pressure by (mean ± SEM) 10.0 ± 1.1 mm Hg but induced no significant changes in the diameter of the arterioles (P = 0.83). The isometric exercise had no significant effect on the oxygen saturation in the arterioles supplying the macular area and the retinal periphery (P > 0.42 for both comparisons). However, there was a significant increase in the oxygen saturation in venules draining the retinal periphery to reduce the oxygen extraction from (mean ± SEM) 36.0% ± 2.3% to 30.6% ± 2.1% (P = 0.002) but no significant change in the preexisting low oxygen extraction in the macular area that changed from (mean ± SEM) 18.2% ± 3.0% to 16.2% ± 1.9% (P = 0.37). CONCLUSIONS. Minor changes in the arterial blood pressure can induce changes in retinal rheology with significant regional variation. The finding may help explain regional variations in manifestations of retinal vascular disease such as hyperpermeability in the macular area and capillary occlusion in the retinal periphery.

Aim This study aimed to investigate the effect of different probe placements on the ventral and dorsal sides of the same finger using pulse oxygen saturation monitoring. Methods This clinical trial used a convenience sampling method in patients admitted to the Second Hospital of Hebei Medical University. We enrolled 1330 patients from March to July 2018, including patients who were hospitalized in the intensive care unit (n = 258) and in the general ward (n = 1072). Pulse oxygen saturation measurements obtained from the ventral and dorsal sides of the same finger were compared. This work adhered to the STROBE checklist requirements. Results We found that pulse oxygen saturation measurements between the dorsal and ventral sides of a finger were not affected by different fingers, disease types, the application of a ventilator, vasoactive drugs, the conscious state of the patient or the instrument model. Conclusion Our findings suggested no significant difference in saturation measurements with variation in the placement of the pulse oxygen saturation measurement instrument between the dorsal and ventral sides of a finger, regardless of illness severity. We believe that these results could simplify the monitoring procedures performed by nurses and eliminate worries concerning the inaccuracy of data because of varied probe positions.

(1) Background: The aim of our study was to investigate the relationship between retinal metabolic alterations (retinal vessel oximetry, RO) and structural findings (retinal vessel diameter, central retinal thickness and retinal nerve fiber layer thickness, RNFL) in patients with inherited retinal diseases (IRDs). (2) Methods: A total of 181 eyes of 92 subjects were examined: 121 eyes of 62 patients with IRDs were compared to 60 eyes of 30 healthy age-matched controls. The retinal vessel oximetry was performed with the oxygen saturation measurement tool of the Retinal Vessel Analyser (RVA, IMEDOS Systems UG, Jena, Germany). The oxygen saturation in all four major peripapillary retinal arterioles (A-SO2, %) and venules (V-SO2, %) were measured and their difference (A-V SO2, %) was calculated. Additionally, retinal vessel diameters of the corresponding arterioles (D-A, µm) and venules (D-V, µm) were determined. The peripapillary central retinal thickness and the RNFL thickness were measured using spectral domain optical coherence tomography (SD-OCT) (Carl Zeiss Meditec, Dublin, CA, USA). Moreover, we calculated the mean central retinal oxygen exposure (cO2-E, %/µm) and the mean peripapillary oxygen exposure (pO2-E, %/µm) per micron of central retinal thickness and nerve fiber layer thickness by dividing the mean central retinal thickness (CRT) and the RNFL thickness with the mean A-V SO2. (3) Results: Rod-cone dystrophy patients had the highest V-SO2 and A-SO2, the lowest A-V SO2, the narrowest D-A and D-V and the thickest RNFL, when compared not only to controls (p ≤ 0.040), but also to patients with other IRDs. Furthermore, in rod-cone dystrophies the cO2-E and the pO2-E were higher in comparison to controls and to patients with other IRDs (p ≤ 0.005). Cone-rod dystrophy patients had the lowest cO2-E compared to controls and patients with other IRDs (p ≤ 0.035). Evaluated in central zones, the cO2-E was significantly different when comparing cone-rod dystrophy (CRD) against rod-cone dystrophy (RCD) patients in all zones (p &lt, 0.001), whereas compared with controls and patients with inherited macular dystrophy this was observed only in zones 1 and 2 (p ≤ 0.018). The oxygen exposure was also the highest in the RCD group for both the nasal and the temporal peripapillary area, among all the evaluated groups (p ≤ 0.025). (4) Conclusions: The presented metabolic-structural approach enhances our understanding of inherited photoreceptor degenerations. Clearly demonstrated through the O2-E comparisons, the central and the peripapillary retina in rod-cone dystrophy eyes consume less oxygen than the control-eyes and eyes with other IRDs. Rod-cone dystrophy eyes seem to be proportionally more exposed to oxygen, the later presumably leading to more pronounced oxidative damage-related remodeling.

The aim of this study was to determine if there is a difference in 6-min walk test (6MWT) distance when the assessor accompanies the patient to continuously measure peripheral oxygen saturation (SpO2) compared to the patient walking unaccompanied. We conducted a randomised crossover study to evaluate the impact of the assessor walking with the patient during the 6MWT (6MWTwith) versus the patient walking alone (6MWTwithout). At the end of a pulmonary rehabilitation programme, each patient performed two 6MWTs in random order and separated by a 30-min rest. 49 patients with chronic obstructive pulmonary disease (COPD) (Global Initiative for Obstructive Lung Disease classification II–IV) were included. In a regression model adjusting for period and subject, accompanying the patient resulted in a lower walking distance (mean difference −9.1 m, 95% CI −13.9– −4.3, p=0.0004). Notably, six patients walked more than 30 m farther (minimal important difference) in one of the two conditions (6MWTwith: n=1, 6MWTwithout: n=5). There were no between-sequence-group differences in heart rate, dyspnoea, leg fatigue and SpO2. The median (interquartile range) number and duration of SpO2 signal artefacts were high but not different between the experimental conditions (6MWTwith: 17 (4–24), 34 s (7–113 s); 6 MWTwithout: 11 (3–26), 24 s (4–62 s)). At a study population level, we observed a statistically significant difference in 6MWT distance between the two experimental conditions; however, the magnitude of difference was small and may not be clinically relevant. Nevertheless, in a clinical setting, unaccompanied walking resulted in a substantially higher walking distance in individual patients, pointing towards strictly standardised testing methodology, in particular in pre–post study designs., Accompanied walking during a 6MWT versus unaccompanied walking results in shorter walked distance (mean difference −9.1 m, 95% CI −13.9– −4.3 m). No differences in nadir SpO2 or oximetry artefacts were noted between accompanied and unaccompanied walking. https://bit.ly/3tBjfCq

Objectives RBCs are known to undergo deleterious changes during storage, known as storage lesions, which have been shown to result in decreased oxygen-carrying capacity. However, there is inadequate literature describing the effects of stored RBC allogeneic transfusion on oxygen parameters in vivo. The oxygen standard parameters were retrospectively assessed before and after RBC transfusion. Methods Patients who received 1 RBC transfusion were assessed for hemoglobin (Hb) levels, peripheral capillary oxygen saturation (Spo2), and partial pressure of arterial oxygen (Pao2) from 12 hours before and 24 hours after transfusion. Results In total, 78 patients who were monitored by Spo2 and 28 patients monitored by Pao2 were included in this analysis. Following RBC transfusion, Hb levels increased significantly (P Conclusions This single-center, retrospective study revealed evidence of significantly decreased oxygenation and tissue perfusion after single-unit RBC transfusion, despite corrected Hb levels.

SUMMARY Hepatopulmonary Syndrome (HPS) is a complication of cirrhosis that worsens the disease's prognosis, pre and post liver transplant. The objective of this study is to analyze the prevalence of HPS in cirrhotic patients at our service and to correlate it with oxygen saturation (SatO2) using a pulse oximeter to evaluate if this is useful as a screening test for HPS. A prospective study was conducted in patients with hepatic cirrhosis conventionally selected from 2014 to 2016. All the patients underwent an echocardiogram with microbubbles and oxygen saturation measurement by pulse oximetry. Those with intrapulmonary shunt were submitted to arterial blood gas analysis. The relationship between oxygen saturation and HPS was assessed by the multivariate model of binary logistic regression. We analyzed 77 patients, and 23.3% (18 patients) had all criteria for HPS. The relationship between HPS and SatO2 did not show statistical significance, even after the variables were adjusted for sex, age, and smoking. Oxygen saturation alone was not able to detect HPS in the sample of cirrhotic patients. More accurate methods for screening and diagnosis of the syndrome should be used. RESUMO A Síndrome Hepatopulmonar (SHP) é uma complicação da cirrose que piora o prognóstico da doença pré e pós-transplante hepático. O objetivo do trabalho é analisar a prevalência de SHP em pacientes cirróticos de nosso serviço e correlacioná-la com a saturação de oxigênio (SatO2) pelo oxímetro de pulso, e avaliar se este seria útil como um exame de triagem no diagnóstico de SHP. Foi realizado um estudo prospectivo em pacientes portadores de cirrose hepática no período de 2014 a 2016. Todos os pacientes foram submetidos a um ecocardiogama com microbolhas e a saturação de oxigênio pela oximetria de pulso. Aqueles com shunt intrapulmonar foram submetidos a gasometria arterial. A relação entre a saturação de oxigênio e SHP foi avaliada pelo modelo multivariado de regressão logística binário. Foram analisados 77 pacientes, destes 23,3% (18 pacientes) apresentaram todos os critérios para SHP. A relação entre a SHP com a SatO2 não obteve significância estatística, mesmo após as variáveis terem sido ajustadas pelo sexo, idade e tabagismo atual ou passado. A saturação de oxigênio, de forma isolada, não foi capaz de distinguir a SHP na amostra de pacientes cirróticos em nosso estudo. Deve-se utilizar métodos mais acurados para a triagem e diagnóstico dessa síndrome.

Introduction: It is difficult to determine illness severity for coronavirus disease 2019 (COVID-19) patients, especially among stable-appearing emergency department (ED) patients. We evaluated patient outcomes among ED patients with a documented ambulatory oxygen saturation measurement. Methods: This was a retrospective chart review of ED patients seen at New York University Langone Health during the peak of the COVID-19 pandemic in New York City. We identified ED patients who had a documented ambulatory oxygen saturation. We studied the outcomes of high oxygen requirement (defined as >4 liters per minute) and mechanical ventilation among admitted patients and bounceback admissions among discharged patients. We also performed logistic regression and compared the performance of different ambulatory oxygen saturation cutoffs in predicting these outcomes. Results: Between March 15–April 14, 2020, 6194 patients presented with fever, cough, or shortness of breath at our EDs. Of these patients, 648 (11%) had a documented ambulatory oxygen saturation, of which 165 (24%) were admitted. Notably, admitted and discharged patients had similar initial vital signs. However, the average ambulatory oxygen saturation among admitted patients was significantly lower at 89% compared to 96% among discharged patients (p

Non-invasive ambulatory estimation of blood oxygen saturation has emerged as an important clinical requirement to detect hypoxemia in the delayed post-infective phase of COVID-19, where dangerous hypoxia may occur in the absence of subjective breathlessness. This immediate clinical driver, combined with the general quest for more personalised health data, means that pulse oximetry measurement of capillary oxygen saturation (SpO2) will likely expand into both the clinical and consumer market of wearable health technology in the near future. In this study, we set out to establish the feasibility of SpO2 measurement from the ear canal as a convenient site for long term monitoring, and perform a comprehensive comparison with the right index finger - the conventional clinical measurement site. During resting blood oxygen saturation estimation, we found a root mean square difference of 1.47% between the two measurement sites, with a mean difference of 0.23% higher SpO2 in the right ear canal. Through the simultaneous recording of pulse oximetry from both the right ear canal and index finger during breath holds, we observe a substantial improvement in response time between the ear and finger that has a mean of 12.4 seconds and a range of 4.2 - 24.2 seconds across all subjects. Factors which influence this response time, termed SpO2 delay, such as the sex of a subject are also explored. Furthermore, we examine the potential downsides of ear canal blood oxygen saturation measurement, namely the lower photoplethysmogram amplitude, and suggest ways to mitigate this disadvantage. These results are presented in conjunction with previously discovered benefits such as robustness to temperature, making the case for measurement of SpO2 from the ear canal being both convenient and superior to conventional finger measurement sites for continuous nonintrusive long term monitoring in both clinical and everyday-life settings.

Background and Aims Patients undergoing hemodialysis (HD) often develop cerebral disease complications. Cerebral tissue regional oxygen saturation (rSO2) through near-infrared spectroscopy (NIRS) is a non-invasive method for cerebral tissue oxygenation monitoring. The aim of the study was to investigate the relationship between rSO2 and hemodialysis in stable HD patients. Additionally, we wanted to investigate how blood pressure during HD is associated with rSO2. Method This is a single centre cross-sectional study in clinically stable HD patients. Cerebral rSO2 was monitored at the forehead 10min before, during and 10min after HD, using an INVOS 5100C device (Medtronic, United Kingdom). Results Thirty-nine stable HD patients (23 men and 16 women; mean age, 62.4 ± 14.6 years were recruited. Dialysis vintage was 65.7 ± 72.1 months, 9 patients had diabetes mellitus, 12 had vascular disease while 14 were smokers. The baseline rSO2 levels (49.6±9.1 %) were significantly lower in HD patients compared with historic results on healthy subjects. We found no difference in rSO2 results in patients with diabetes mellitus, vascular disease or smoking. Although we found a decrease (figure) in rSO2 when patients start dialysis (10min before vs 10min after starting dialysis 49.6±9.1 vs 48.1±9.9 %, p=0.021) rSO2 value returned to baseline after dialysis (10min before vs 10min after dialysis 49.6±9.1 vs 49.9±5.9 %, p=ns. Systolic blood pressure scientifically dropped during the first hour of dialysis (146.7 ± 21.1 vs 137.3 ± 24.6, p=0.03) and systolic blood pressure drop correlated with rSO2. Three patients developed hypotensive episodes requiring iv fluids but these hypotensive episodes had no correlation with rSO2 variations. Conclusion Cerebral rSO2 decreases while patients are on dialysis but return to baseline after dialysis. Blood pressure variations correlate with rSO2 levels but rSO2 do not forecast hypotensive episodes on dialysis.

Background and Aims Intradialytic hypotension (IDH) involves a reduced tolerance to hemodialysis (HD), a poor quality of life and is associated with mortality. Intradialytic monitoring systems (blood pressure, heart rate, volemia) are not able to identify patients at greater risk of IDH. IDH is a hemodynamic phenomenon and attention has recently been given to the evaluation of oxygen saturation to evaluate its role in IDH. Oxygen Extraction Ratio (OER), the ratio between SaO2 and ScvO2, is a parameter used to monitor parenchyma oxygen consumption and stress. Recent evidence showed that HD patients with a greater delta OER (ΔOER) during HD (threshold 40%)had higher mortality risk. OER could be a new monitoring instrument to measure hemodialysis induced sub-clinical parenchyma hypoxia and stress, two elements included in the pathogenesis of IDH. The aim of the study was to evaluate the relationship between OER and IDH incidence. Method Inclusion criteria: age ≥18 years, chronic HD treatment by means of permanent jugular CVC, no evidence of acute underlying illness. We evaluated OER ([(SaO2 − ScvO2)/SaO2] × 100) before HD and at 15’, 30’, 60’ and post HD in three HD sessions (HD OER sessions). For the statistic analysis we considered for each patient the median OER value obtained from the three HD OER sessions. Then we started the follow-up study with a minimum follow-up of three months and end follow-up of two years, to record IDH (defined according to K/DOQI guidelines) for each patient. We divided the population in two groups using as a threshold the median percentage number of IDH in our population and evaluate the differences between the obtained two groups in pre HD OER, Delta OER and intradialytic OER trends. Results During the follow-up period (mean 12 ± 1.2 months), we enrolled 28 patients with permanent jugular CVC: 13 males and 15 females, aged 74±2.6 years, HD vintage 46 ± 6.5 months. The HD OER sessions for each patient were asymptomatic. Pre HD OER was 34 ± 1.4, post HD OER 46 ± 1.8, with a Delta OER of 39 ± 5 %. OER change during HD was evident since after 15 minutes (OER% 15’: 40 ± 1.2 p 3.6). The two groups were not different for age (76 ± 2.4 vs 73 ± 3.0 years; p 3.6 group had 159 IDH out of a total of 1911 sessions (9%), while IDH % ≤ 3.6 group had 27 IDH out of 2431 sessions (0.9%). Pre HD OER values were not different between the groups while the IDH % >3.6 group had greater delta OER% than the IDH % ≤ 3.6 group (43 ± 4.8 vs. 35 ± 3.0 %; p 3.6 group (ΔOER 20± 3.0 % vs. 8.0 ± 3.0 %; IDH % > 3.6 group vs. IDH % ≤ 3.6 group, p Conclusion Our data show that intradialytic ΔOER, representative of the extent of tissue hypoxic stress, identifies patients at greater risk of IDH. In particular, a ΔOER of 20% after the first 15 minutes of HD and of 43% at the end of the HD session characterizes the more hemodynamically fragile patients. The measurement of the OER can be a new and easy monitoring instrument to identify the most hemodynamically fragile patients already after the first 15 minutes of HD treatment.

The main role of the respiratory system is to maintain a stable and adequate level of gas exchange; therefore, the ideal monitoring for this function should include a form of gas exchange measurement that is continuous and noninvasive, particularly for children. There are several methods to determine the quantities of oxygen and carbon dioxide in the blood, lung air, or tissues. Pulse oximetry is a noninvasive and readily available method that indirectly determine the concentration or saturation of oxygen in the blood. Many factors may influence the reading of pulse oximetry, and it is important to recognize its limitations.

INTRODUCTION: Adequate oxygenation is one of the primary goals of mechanical ventilation. Maintenance of adequate oxygenation and prevention of hypoxemia are the primary goals for the battlefield casualty, but military operations have unique concerns. In military operations, oxygen is a limited resource. A portable oxygen concentrator has the advantage of operating solely from electrical power and theoretically is a never-exhausting supply of oxygen. Our previous bench work demonstrated that the pulsed dose setting of the concentrator can be used in concert with the ventilator to maximize oxygen delivery. We evaluated this ventilator/concentrator system with closed loop control of oxygen output in a porcine model. MATERIALS AND METHODS: The Zoll 731 portable ventilator and Sequal Saros portable oxygen concentrator were used for this study. The ventilator and concentrator were connected via a USB cable to allow communication. The ventilator was modified to allow closed loop control of oxygen based on the oxygen saturation (SpO2) via the integral pulse oximetry sensor. The ventilator communicates with the concentrator to increase or decrease oxygen bolus size to maintain a target SpO2 of 94%. Three separate experiments were conducted in this study. Experiments 1 and 2 used oxygen bolus sizes 16-96 mL in 16-mL increments and experiment 3 used 1 mL increments. The oxygen bolus was delivered from the concentrator and injected into the ventilator circuit at the patient connector. Six pigs were used for each experiment. Experiment 1, done without lung injury, was completed to determine the optimum timing during the respiratory cycle for injecting the oxygen bolus. Lung injury for experiments 2 and 3 was induced in the animals by warmed saline lavage via the endotracheal tube until PaO2/FIO2 decreased to

AIM This study is a quasi-experimental research that was conducted to evaluate the effects of bathing on vital signs and oxygen saturation in intubated children who are connected to mechanical ventilation. METHODS The study sample consisted of children who are treated in the pediatric intensive care unit, University of Istanbul Cerrahpasa Faculty of Medicine Hospital. A total of 60 children who met the criteria of the sample group were included in the study. The children were given bed bathing with plain warm water of 32°C to 38°C on 3 different days. The vital signs and oxygen saturation values of the children were measured before bathing, just after bathing, and 30 minutes after bathing them. RESULTS Most of the children (65%) were on mechanical ventilation because of respiratory system diseases; 91.7% of them were connected to mechanical ventilation with endotracheal tube. The first bed bathing of children was given mean of 1.54 ± 3.57 days after their hospitalization, and bathing durations were mean of 18.3 minutes. The vital signs (pulse, blood pressure, body temperature) were compared before and after bed bathing, and it was observed that the values before bathing, just after bathing, and 30 minutes after bathing had advanced level of difference (P < .001). The lowest values of all signs except body temperature were obtained 30 minutes after bed bathing. When oxygen saturation measurement values before bathing (94.5%) and after bathing were compared, it was found that the highest values (97.3%) were obtained 30 minutes after bed bathing. CONCLUSION The bed bathing positively affected the vital signs and oxygen saturation values in intubated children connected to the mechanical ventilation. Yet, there is still a need for more research to test the effects of bed bathing on respiratory and circulatory function.

Introduction Daridorexant is a dual orexin receptor antagonist developed for the treatment of insomnia. The effect of the highest phase-3 dose of 50 mg daridorexant on nighttime respiratory function was evaluated in patients with mild/moderate obstructive sleep apnea (OSA). This study showed that repeated doses of daridorexant had no clinically meaningful effect on nighttime respiration (i.e., apnea-hypopnea index [AHI] and peripheral oxygen saturation [SpO2]). In the same study, other relevant respiratory endpoints were evaluated. Methods In this randomized, double-blind, placebo-controlled, two-period, crossover study, daridorexant or placebo was administered in each period once daily for 5 consecutive nights to 28 patients. Treatment differences (daridorexant – placebo) for total number and mean/longest duration of apneas and hypopneas as well as mean and lowest SpO2 during apnea/hypopnea events in Night 5 were explored using linear mixed-effects modeling. Treatment differences for the above-mentioned endpoints versus AHI during TST at baseline (i.e., OSA severity) was analyzed by linear regression using least square approach. Results Of 28 patients enrolled, 25 completed the study and were included in the analysis (n=15/10 with mild/moderate OSA; mean [standard deviation, SD] AHI: 16.3 events/h [8.2]). Compared to placebo, daridorexant increased mean duration of TST and accordingly to a not statistically significant extent the mean number of apneas + hypopneas by 16.4 events (n=103 versus 86.2; 90% confidence interval [CI]: -0.4–33.2]) without difference in mean [SD] AHI between daridorexant (15.1 events/h [7.9] and placebo (14.2 [7.7]). No treatment difference was detected for mean (0.0 sec [-2.6–2.7]) or longest (0.8 sec [-8.9–10.5]) duration of apneas nor for mean (0.2 sec [-2.2–2.5]) or longest (8.3 sec [6.4–23.1]) duration of hypopneas. No treatment difference was observed for mean (0.3% [-0.2–2.1]) and lowest (0.9% [0.3–2.1]) SpO2 during apnea/hypopnea events. Treatment differences for any of the evaluated endpoints did not significantly correlate with AHI at baseline as a marker of OSA severity (r2 ≤ 0.09). Conclusion Daridorexant can safely be administered to patients with mild/moderate OSA as treatment differences for respiratory-related endpoints were not of statistical significance and independent of disease severity in the studied population. Support (if any) Funded by Idorsia Pharmaceuticals Ltd.

Cerebral hypoxia is a severe injury caused by oxygen deprivation to the brain. Hypoxia in the neonatal period increases the risk for the development of neurological disorders, including hypoxic-ischemic encephalopathy, cerebral palsy, periventricular leukomalacia, and hydrocephalus. It is crucial to recognize hypoxia as soon as possible because early intervention improves outcomes. Photoacoustic imaging, using at least two wavelengths, through a spectroscopic analysis, can measure brain oxygen saturation. Due to the spectral coloring effect arising from the dependency of optical properties of biological tissues to the wavelength of light, choosing the right wavelength-pair for efficient and most accurate oxygen saturation measurement and consequently quantifying hypoxia at a specific depth is critical. Using a realistic neonate head model and Monte Carlo simulations, we found practical wavelength-pairs that quantified regions with hypoxia most accurately at different depths down to 22 mm into the cortex neighboring the lateral ventricle. We also demonstrated, for the first time, that the accuracy of the sO2 measurement can be increased by adjusting the level of light energy for each wavelength-pair. Considering the growing interest in photoacoustic imaging of the brain, this work will assist in a more accurate use of photoacoustic spectroscopy and help in the clinical translation of this promising imaging modality. Please note that explaining the effect of acoustic aberration of the skull is not in the scope of this study.

Blood oxygen saturation (SpO2) measurement is a routinely performed clinical procedure involved in the diagnosis of several critical diseases. However, the most commonly used SpO2 measuring device, known as oximeter, becomes unreliable in the absence of proper body contact. A non-contact, non-invasive, real-time device is desirable for accurate measurement and continuous monitoring of SpO2. This paper presents a polarized imaging-based integrated solution for SpO2 measurement. The polarization filters are used to separate light components reflecting from deep and superficial layers of skin. The ratio of intensities of the two components is found to have a linear relationship with SpO2 levels. In contrast to the existing SpO2 measurement techniques, the proposed method uses a single light source. The experiments are performed with 15 human subjects (11 male and 4 female) using different wavelengths of light. A statistically significant relationship is observed between SpO2 and the intensity ratios for red light (correlation coefficient $\textrm {r = 0.6426}$ with p = 0.001965 and mean error = 0.0626). The experiments are repeated using white light, and a similar relationship is observed ( $\textrm {r = 0.5603}$ with p = 0.00947 and mean error = −0.9289). Furthermore, the Bland–Altman analysis shows that the results of the proposed method are consistent with the reference data. This suggests that a real-time integrated polarized imaging-based SpO2 measurement device can be developed based on the proposed method.

There are currently no evidence-based oxygen saturation targets for treating children with life-threatening conditions. We reviewed evidence of SpO2 targets for oxygen therapy in children with emergency signs as per WHO Emergency Triage Assessment and Treatment guidelines. We systematically searched for physiological data and international guidelines that would inform a safe approach. Our findings suggest that in children with acute lung disease who do not require resuscitation, a threshold SpO2 for commencing oxygen of 90% will provide adequate oxygen delivery. Although there is no empirical evidence regarding oxygen saturation to target in children with emergency signs from developing countries, a SpO2 of ≥ 94% during resuscitation may help compensate for common situations of reduced oxygen delivery. In children who do not require resuscitation or are stable post resuscitation with only lung disease, a lower limit of SpO2 for commencing oxygen of 90% will provide adequate oxygen delivery and save resources.

Introduction Agreement between automated standard respiratory event scoring and a novel, validated, and patented oximetry-based algorithm was assessed. Methods The standard apnea-hypopnea index (AHI) was derived by adding apneas (flow drop >= 90% for 10 to 30 s) and hypopneas (flow drop >= 30% for 10 to 60 s with oxygen saturation (SpO2) dropping >=3%). The novel oxygen index (ODI4) was derived by scoring events where SpO2 dropped in each of three successive samples and cumulatively by >= 4%. Agreement was assessed by Bland-Altman analysis Results AHI versus ODI4 and Bland-Altman plots showed a high prevalence of AHI > ODI4 when AHI was< 30/h. Negative difference outliers were frequent when mean index difference was > 30/h. There was a bias of 2.83/h in the difference between AHI and ODI4 with upper and lower confidence limits of 22.0/h and -16.3/h. Conclusion Standard respiratory event scoring overestimates respiratory disturbance compared to a novel oximetric index. Standard automated scoring frequently over scores events when basal flow amplitude is low. Support None.

Introduction Refractory spasticity in children is treated with intrathecal baclofen (ITB), which may worsen both central and obstructive breathing events. Sleep disordered breathing (SDB) is seldom investigated prior and/or subsequent to placement of ITB and there are currently no standardized protocols. This study aims to compare occurrence of SDB pre/post ITB placement. Methods Retrospective chart review revealed 104 patients started on ITB therapy from 2009-2019 and those who had pre and/or post ITB polysomnograms (PSG) were included. Medical history and PSG parameters were extracted. Comparison of paired results will occur using the Wilcoxon Signed Rank Sum Tests once collection is complete. Results Thirty-seven patients were identified having pre and/or post ITB PSGs. Results in mean ± SD show: age was 11 ± 4 years and 65% were male. Twenty-five pre ITB PSG had an oAHI of 4 ± 5 with 22/25 (88%) having SDB. There were 15/25 (60%) with mild OSA (oAHI >1 but < 5) and 7/25 (28%) with moderate-severe OSA (oAHI > 5/hr). CAI was 1 ± 2 and oxygen saturation nadir was 88 ± 9 %. Sixteen post ITB PSG had an oAHI of 8 ± 13 with 100% having SDB. There were 11/16 (69%) with mild OSA and 5/16 (31%) with moderate-severe OSA. CAI was 3 ± 7 and oxygen saturation nadir was 84 ± 8 %. Ten patients were initiated on non-invasive ventilation, one on supplemental oxygen and two had adenotonsillectomy. Conclusion Initial data shows high occurrence of SDB in patients pre and post ITB placement leading to medical or surgical intervention in 35%. Post ITB PSGs showed worsened oAHI and CAI and lower oxygen saturation nadir. Possible mechanisms include depression of central respiratory drive and decreased pulmonary reserves. This study may help stratify and address risks of ITB for those with refractory spasticity and SDB. Support None

Introduction Obstructive sleep apnea (OSA) is a common sleep breathing disorder with significant public health consequences. Despite this, no clinically available objective molecular biomarkers to diagnose, risk stratify and quantify treatment efficiency exist. To this end, high-throughput metabolomics data could serve as a valuable quantitative tool. Methods We designed a pilot study to investigate the metabolomic effects of OSA and CPAP treatment. Blood serum samples were collected from OSA patients and healthy controls matched with respect to age (±5 years), BMI (±2.5 kg/m2) and gender (N = 20/group). Samples from OSA patients were obtained before and after continuous positive airway pressure (CPAP) treatment. Polar metabolites were analyzed using a targeted ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) metabolomics technique. Results Supervised multivariate analysis using serum metabolic values of OSA patients and healthy controls showed a significantly different overall metabolic profile between the two groups (orthogonal partial least squares discriminant analysis [OPLS-DA] Q2=0.25, p=0.04). Acetylornithine, choline, cytidine, dodecenoylcarnitine, methionine sulfoxide and 3-indoxylsulfate were among the most perturbed metabolites. Major metabolic pathways altered in the OSA patients were methionine and phospholipid metabolism, as well as gut microbial co-metabolism. Lysophosphatidylcholine (16:0), a phospholipid metabolite, demonstrated significant linear association with improved oxygen saturation nadir post CPAP treatment (R2 = 0.57), suggesting the metabolic features may be used as prognostic clinical biomarkers. Conclusion These results suggest that OSA significantly impacts blood metabolites, which could potentially be used to establish OSA biomarkers. Moreover, specific metabolic features are associated with post CPAP improvement, such as phospholipids, suggesting a functional association of these metabolites that may help us understand the heterogeneity of OSA. Overall, these results demonstrate the potential of metabolic profiling to develop quantitative molecular markers of OSA. Further studies are underway to validate these findings and investigate the utility of metabolic profiles to objectively measure CPAP efficacy. Support The work was supported by the program project grant P01 HL094307.

Introduction Robin Sequence (RS) involves the clinical triad of micrognathia, glossoptosis and cleft palate. There is a spectrum of severity, but most neonates with RS have upper airway obstruction, resulting in severe obstructive sleep apnea, sometimes requiring surgical interventions such as tongue-lip adhesion, mandibular distraction, or tracheostomy. We present an infant with RS and severe obstructive sleep apnea which was managed with supplemental oxygen. Report of Case Our patient was born at 39 weeks gestation with RS. He had a normal DNA microarray. He was discharged after a 3 week NICU hospitalization for poor feeding. Over the next 2 months, he had poor weight gain and worsening obstructive breathing and was evaluated by craniofacial surgery at that time. Room air polysomnography (PSG) was recommended and revealed an AHI of 21, REM AHI of 48, supine AHI of 25, prone AHI of 19, mean SPO2 of 98%, minimum SPO2 of 61%, and normal capnography with 0% of the time spent > 50 mmHg. A repeat sleep study on 1/4LPM oxygen in the supine position revealed an AHI of 1.7, mean SPO2 of 99%, minimum SPO2 of 92%, and normal capnography. He was discharged on supplemental oxygen. At 4 months of age, he had good weight gain. At 10 months of age, room air PSG revealed persistent OSA with an AHI of 7.2, REM AHI of 21, mean SPO2 of 97%, minimum SPO2 of 81%, and normal capnography. At age 3 yrs, his PSG on room air showed resolution of his OSA with an AHI of 0.6, mean SPO2 of 97%, minimum SPO2 of 87% and normal capnography. Conclusion This case illustrates the spectrum of severity of RS and the utility of low flow oxygen to treat OSA in this patient population.

Introduction Objective: Identify prevalence and factors associated with hypoxia and blood pressure changes during MAC anesthesia for inpatient burn dressing change. Methods Retrospective chart review on 112 adult inpatients undergoing 1 or more burn dressing changes under MAC from March 2014 to December 2017 at a single burn center. Results Study population was 112 burn inpatients undergoing 210 burn dressing changes under MAC. Median age was 43 years (range 18–93) with 78% male and 95% Caucasian. Average BMI was 29.7 (range 18–66). Average % total body surface area (TBSA) burn was 24% (range 1%-70%). Number of MAC dressing changes per patient was 1 to 16 with most (71.4%) undergoing 1 MAC dressing change. Among 210 MAC cases, 5 involved a hypoxemic event (defined as a % O2 saturation of < 90%) and 14 involved a blood pressure changed (defined as a mean arterial pressure (MAP) of < 60 mmHg) on 7 different patients Three of the hypoxic events were also associated with hypotension (1.4%) None of these events were associated with poor outcomes. Conclusions MAC anesthesia for dressing changes are performed on inpatients during all stages of the burn recovery. Anesthesia is involved with the initial dressing changes on the critical care individuals. The MAC anesthesia is titrated to the condition of the patient with very low frequency of hypoxia or severe hypotension. Applicability of Research to Practice Burn dressing changes are challenging anesthesias because of the often associated co-morbidities of the presenting patients. Other factors that are considered are the NPO status and nutritional requirements of the patients. The desire to accomplish the dressing changes with the least amount of disruption of this while caring for these ill patients can be safely accomplished with MAC dressing changes. This provides an incredibly safe environment for the patient with the rapidly titratable medications that allow the dressing changes to be completed efficiently.

Background Anastomotic leak remains a significant cause of morbidity and mortality after colorectal surgery. Among multiple risk factors considered, hypoxia–ischaemia is considered to be a primary cause of intestinal anastomotic leakage. The aim of this experimental study was to assess safety, usability for surgical tasks, and efficacy of a newly developed oxygen‐producing suture material in the healing of colonic anastomoses under critical conditions. Methods An oxygen‐producing suture material was produced that is capable of releasing oxygen directly into the surrounding tissue. Off‐the‐shelf sutures loaded with calcium peroxide nano‐crystals and covered with poly(d,l‐lactide‐co‐glycolide) were assessed in vitro and in a rat model of hypoxic colonic anastomosis. Results In vitro assessment showed that these sutures can increase oxygen levels in a hypoxic environment. Potential oxygen byproducts did not seem to have a negative impact on the viability of intestinal cells. The use of oxygen‐producing sutures in vivo resulted in increased tissue oxygen saturation, measured by visible light spectroscopy, and increased mechanical stability of the anastomosis. Conclusion Oxygen‐producing suture material increased tissue oxygen saturation and mechanical stability of colonic anastomosis in a rat model.Surgical relevanceLeakage of anastomoses remains a significant problem after colorectal surgery.An oxygen‐producing suture material was produced that was shown to be safe in vitro and significantly improved several aspects of healing of colonic anastomoses in an animal model.Oxygen‐producing suture material or stapler devices might help to reduce the risk of anastomotic leak of intestinal anastomoses under physiological and critical conditions such as hypoxia., Anastomotic leak remains a significant problem after colorectal surgery, and administration of supplemental perioperative oxygen has been shown to improve healing of colorectal anastomoses. The manufacture of an oxygen‐producing suture material is described; experiments showed that it improved some aspects of the healing of bowel anastomoses. Oxygen‐releasing suture (or stapling) material might be a future potential application to reduce the risk of anastomotic leak under critical conditions, such as hypoxia. Increased mechanical stability by oxygen‐producing sutures.

Background Automated diagnostic device to measure child’s vital sign is a global unmet demand. Having separate diagnostic devices to measure multiple vital signs is more expensive, and can be complex for health workers. An automated “all-in-one” device would help avoiding extra costs as well as maintenance challenges associated with multiple devices. In addition to improve classifying childhood illness, such an automated device would also increase adherence to guidelines, optimal use of antibiotics, and a reduction of unnecessary referrals. Methods We studied an automated device in Malawi, which was designed to measure multiple key vital signs (SPO2, respiratory rate, temperature) among newborn, infant and children Results Preliminary analyses of valid PPG signals, video annotated respiratory count and CO2 sensor data revealed the following key results: - For SPO2, the performance of the target probe among 170 subjects appears extremely well with even the smallest and largest children. - Among 145 subjects with valid CO2 data, 93 subjects were fully calm and had a regular breathing pattern. Comparing accelerometry measurements from 93 calm subjects with the reference data, the root of mean square error (RMSE) was only 1.18 respiration per minute (RPM). Excluding four outlier measurements from 145 subjects’ dataset, the RMSE for the remaining 141 subjects was 1.76 RPM. Conclusions This study results demonstrated the proof of concept that the device measures key vital signs among newborn, infants and children Key messages Automated diagnostic device measures key multiple key vital signs (SPO2, respiratory rate, temperature) among newborn, infant and children

Purpose: To assess agreement between different image sizes and analysis protocols for determination of retinal vessel oxygen saturation in the peripapillary retina of healthy individuals. Methods: Retinal oximetry measurements were acquired from 87 healthy volunteers using the IMEDOS Systems oxygen module. The peripapillary retinal vessels were assessed in a concentric annulus around the optic nerve head. Single and average vessel comparisons were made at different image field sizes of 30° and 50°. Comparisons between images obtained at 30° and 50° were made in a subset of 47 of the 87 individuals. Results: All subjects were normotensive and had normal intraocular pressures (9–16 mm Hg). Analyses of agreement between single vessel, averaged vessel, and between different size images were sought by Bland-Altman analyses, of which all yielded a low bias (

Peripheral arterial occlusive disease has a high risk to occur in the lower extremity which causes low oxygen saturation level in muscle tissue, especially after exercise. A muscle tissue oxygen saturation measurement system was developed to detect the insufficient blood supply to lower limb.

Polysomnography is the main diagnostic instrument for sleep apnea, but it is not convenient for patient to take frequent measurements at home. An in-home sleep test is a solution to help physicians to collect more information. Sleep medicine societies suggest that a home sleep-apnea testing device should measure at least oxygen saturation and breathing signals. To reduce the discomfort of measurement during sleep, the device should be also as small as possible. One possible measuring site for both signals is at the nose. The accuracy of oxygen saturation measurement relies on the quality of photoplethysmographic signals (PPG). PPG signals of red and near-infrared light measured at the nasal septum and nasal wing were compared. PPG signals were also measured at different body postures includes standing, sitting and supine.