Effects of moderate alcohol consumption and hypobaric hypoxia: implications for passengers' sleep, oxygen saturation and heart rate on long-haul flights.

BACKGROUND: Passengers on long-haul flights frequently consume alcohol. Inflight sleep exacerbates the fall in blood oxygen saturation (SpO2) caused by the decreased oxygen partial pressure in the cabin. We investigated the combined influence of alcohol and hypobaric hypoxia on sleep, SpO2 and heart rate. METHODS: Two groups of healthy individuals spent either two nights with a 4-hour sleep opportunity (00:00-04:00 hours) in the sleep laboratory (n=23; 53 m above sea level) or in the altitude chamber (n=17; 753 hPa corresponding to 2438 m above sea level, hypobaric condition). Participants consumed alcohol before one of the nights (mean±SE blood alcohol concentration 0.043±0.003%). The order of the nights was counterbalanced. Two 8-hour recovery nights (23:00-07:00 hours) were scheduled between conditions. Polysomnography, SpO2 and heart rate were recorded. RESULTS: The combined exposure to alcohol and hypobaric condition decreased SpO2 to a median (25th/75th percentile) of 85.32% (82.86/85.93) and increased heart rate to a median (25th/75th percentile) of 87.73 bpm (85.89/93.86) during sleep compared with 88.07% (86.50/88.49) and 72.90 bpm (70.90/78.17), respectively, in the non-alcohol hypobaric condition, 94.97% (94.59/95.33) and 76.97 bpm (65.17/79.52), respectively, in the alcohol condition and 95.88% (95.72/96.36) and 63.74 bpm (55.55/70.98), respectively, in the non-alcohol condition of the sleep laboratory group (all p<0.0001). Under the combined exposure SpO2 was 201.18 min (188.08/214.42) below the clinical hypoxia threshold of 90% SpO2 compared with 173.28 min (133.25/199.03) in the hypobaric condition and 0 min (0/0) in both sleep laboratory conditions. Deep sleep (N3) was reduced to 46.50 min (39.00/57.00) under the combined exposure compared with both sleep laboratory conditions (alcohol: 84.00 min (62.25/92.75); non-alcohol: 67.50 min (58.50/87.75); both p<0.003). CONCLUSIONS: The combination of alcohol and inflight hypobaric hypoxia reduced sleep quality, challenged the cardiovascular system and led to extended duration of hypoxaemia (SpO2 <90%).

Systemic Arterial Oxygen Levels Differentiate Pre- and Post-capillary Predominant Hemodynamic Abnormalities During Exercise in Undifferentiated Dyspnea on Exertion.

BACKGROUND: Whether systemic oxygen levels (SaO2) during exercise can provide a window into invasively derived exercise hemodynamic profiles in patients with undifferentiated dyspnea on exertion is unknown. METHODS: We performed cardiopulmonary exercise testing with invasive hemodynamic monitoring and arterial blood gas sampling in individuals referred for dyspnea on exertion. Receiver operator analysis was performed to distinguish heart failure with preserved ejection fraction from pulmonary arterial hypertension. RESULTS: Among 253 patients (mean ± SD, age 63 ± 14 years, 55% female, arterial O2 [PaO2] 87 ± 14 mmHg, SaO2 96% ± 4%, resting pulmonary capillary wedge pressure [PCWP] 18 ± 4mmHg, and pulmonary vascular resistance [PVR] 2.7 ± 1.2 Wood units), there was no exercise PCWP threshold, measured up to 49 mmHg, above which hypoxemia was consistently observed. Exercise PaO2 was not correlated with exercise PCWP (rho = 0.04; P = 0.51) but did relate to exercise PVR (rho = -0.46; P < 0.001). Exercise PaO2 and SaO2 levels distinguished left-heart-predominant dysfunction from pulmonary-vascular-predominant dysfunction with an area under the curve of 0.89 and 0.89, respectively. CONCLUSION: Systemic O2 levels during exercise distinguish relative pre- and post-capillary pulmonary hemodynamic abnormalities in patients with undifferentiated dyspnea. Hypoxemia during upright exercise should not be attributed to isolated elevation in left heart filling pressures and should prompt consideration of pulmonary vascular dysfunction.

Treating sleep-disordered breathing of idiopathic pulmonary fibrosis patients with CPAP and nocturnal oxygen treatment. A pilot study : Sleep-disordered breathing treatment in IPF.

INTRODUCTION: Sleep-disordered breathing (SDB) is a major comorbidity in idiopathic pulmonary fibrosis (IPF) and is associated with a poor outcome. There is a lack of knowledge regarding the impact of SDB treatment on IPF. We assessed at one year: (1) the effect of CPAP and/or nocturnal oxygen therapy on IPF regarding lung function, blood mediators, and quality of life; (2) adherence to SDB treatment and SDB changes. METHODOLOGY: This is a prospective study of consecutive newly diagnosed IPF patients initiating anti-fibrotic treatment. Lung function, polysomnography, blood tests and quality of life questionnaires were performed at inclusion and after one year. Patients were classified as obstructive sleep apnoea (OSA), central sleep apnoea (CSA), and sleep-sustained hypoxemia (SSH). SDB therapy (CPAP and/or nocturnal oxygen therapy) was initiated if needed. RESULTS: Fifty patients were enrolled (36% had OSA, 22% CSA, and 12% SSH). CPAP was started in 54% of patients and nocturnal oxygen therapy in 16%. At one-year, polysomnography found improved parameters, though 17% of patients had to add nocturnal oxygen therapy or CPAP, while 33% presented SDB onset at this second polysomnography. CPAP compliance at one year was 6.74 h/night (SD 0.74). After one year, matrix metalloproteinase-1 decreased in OSA and CSA (p = 0.029; p = 0.027), C-reactive protein in OSA (p = 0.045), and surfactant protein D in CSA group (p = 0.074). There was no significant change in lung function. CONCLUSIONS: Treatment of SBD with CPAP and NOT can be well tolerated with a high compliance. IPF patients may exhibit SDB progression and require periodic re-assessment. Further studies to evaluate the impact of SDB treatment on lung function and serological mediators are needed.

Racial and Ethnic Disparities in Occult Hypoxemia Prevalence and Clinical Outcomes Among Hospitalized Patients: A Systematic Review and Meta-analysis.

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 ).

Reaction time in psychomotor vigilance task is related to hypoxic load in males with sleep apnea.

Oxygen saturation (SpO2 )-based parameters are more strongly linked to impaired daytime vigilance than the conventional diagnostic metrics in patients with obstructive sleep apnea (OSA). However, whether the association between SpO2 -based parameters and impaired daytime vigilance is modulated by sex, remains unknown. Hence, we investigated the interplay between sex and detailed SpO2 -based metrics and their association with impaired vigilance in patients with OSA. The study population consisted of 855 (473 males, 382 females) patients with suspected OSA who underwent overnight polysomnography and psychomotor vigilance task (PVT). The population was grouped by sex and divided into quartiles (Q1-Q4) based on median reaction times (RTs) in the PVT. In addition to conventional diagnostic metrics, desaturation severity (DesSev), fall severity (FallSev), and recovery severity (RecovSev) were compared between the sexes and between the best (Q1) and worst (Q4) performing quartiles by using cumulative distribution functions (CDFs). Additionally, sex-specific covariate-adjusted linear regression models were used to investigate the connection between the parameters and RTs. The CDFs showed significantly higher hypoxic load in Q4 in males compared to females. In addition, the DesSev (ß = 8.05, p < 0.01), FallSev (ß = 6.48, p = 0.02), RecovSev (ß = 9.13, p < 0.01), and Oxygen Desaturation Index (ß = 12.29, p < 0.01) were associated with increased RTs only in males. Conversely, the Arousal Index (ß = 10.75-11.04, p < 0.01) was associated with impaired vigilance in females. The severity of intermittent hypoxaemia was strongly associated with longer RTs in males whereas the Arousal Index had the strongest association in females. Thus, the impact of hypoxic load on impaired vigilance seems to be stronger in males than females.

Oxygen saturation thresholds in managing sickle cell disease at US children's hospitals.

BACKGROUND: Adequate oxygen saturation (SpO2 ) is crucial for managing sickle cell disease (SCD). Children with SCD are at increased risk for occult hypoxemia; therefore, understanding SpO2 threshold practices would help identify barriers to oxygen optimization in a population sensitive to oxyhemoglobin imbalances. We investigated SpO2 cutoff levels used in clinical algorithms for management of acute SCD events at children's hospitals across the United States, and determined their consistency with recommended national guidelines (SpO2  > 95%). METHODS: Clinical pathways and algorithms used for the management of vaso-occlusive crisis (VOC) and acute chest syndrome (ACS) in SCD were obtained and reviewed from large children's hospitals in the United States. RESULTS: Responses were obtained from 94% (140/149) of eligible children's hospitals. Of these, 63 (45%) had available clinical algorithms to manage VOC and ACS. SpO2 cutoff was provided in 71.4% (45/63) of clinical algorithms. Substantial variation in SpO2 cutoff levels was noted, ranging from ≥90% to more than 95%. Only seven hospitals (5% of total hospitals and 15.6% of hospitals with clinical algorithms available) specified oxygen cutoffs that were consistent with national guidelines. Hospitals geographically located in the South (46.8%; n = 29/62) and Midwest (54.8%; n = 17/31) were more likely to have VOC and ACS clinical algorithms, compared to the Northeast (26.5%; n = 9/34) and West (36.4%; n = 8/22). CONCLUSION: There is inconsistency in the use of clinical algorithms and oxygen thresholds for VOC and ACS across US children's hospitals. Children with SCD could be at risk for insufficient oxygen therapy during adverse acute events.

Impact of Positive End-Expiratory Pressure and FiO2 on Lung Mechanics and Intrapulmonary Shunt in Mechanically Ventilated Patients with ARDS Due to COVID-19 Pneumonia.

Purpose: This study aimed to investigate the effects of inspired oxygen fraction (FiO2) and positive end-expiratory pressure (PEEP) on gas exchange in mechanically ventilated patients with COVID-19. Methods: Two FiO2 (100%, 40%) were tested at 3 decreasing levels of PEEP (15, 10, and 5 cmH2O). At each FiO2 and PEEP, gas exchange, respiratory mechanics, hemodynamics, and the distribution of ventilation and perfusion were assessed with electrical impedance tomography. The impact of FiO2 on the intrapulmonary shunt (delta shunt) was analyzed as the difference between the calculated shunt at FiO2 100% (shunt) and venous admixture at FiO2 40% (venous admixture). Results: Fourteen patients were studied. Decreasing PEEP from 15 to 10 cmH2O did not change shunt (24 [21-28] vs 27 [24-29]%) or venous admixture (18 [15-26] vs 23 [18-34]%) while partial pressure of arterial oxygen (FiO2 100%) was higher at PEEP 15 (262 [198-338] vs 256 [147-315] mmHg; P < .05). Instead when PEEP was decreased from 10 to 5 cmH2O, shunt increased to 36 [30-39]% (P < .05) and venous admixture increased to 33 [30-43]% (P < .05) and partial pressure of arterial oxygen (100%) decreased to 109 [76-177] mmHg (P < .05). At PEEP 15, administration of 100% FiO2 resulted in a shunt greater than venous admixture at 40% FiO2, ((24 [21-28] vs 18 [15-26]%, P = .005), delta shunt 5.5% (2.3-8.8)). Compared to PEEP 10, PEEP of 5 and 15 cmH2O resulted in decreased global and pixel-level compliance. Cardiac output at FiO2 100% resulted higher at PEEP 5 (5.4 [4.4-6.5]) compared to PEEP 10 (4.8 [4.1-5.5], P < .05) and PEEP 15 cmH2O (4.7 [4.5-5.4], P < .05). Conclusion: In this study, PEEP of 15 cmH2O, despite resulting in the highest oxygenation, was associated with overdistension. PEEP of 5 cmH2O was associated with increased shunt and alveolar collapse. Administration of 100% FiO2 was associated with an increase in intrapulmonary shunt in the setting of high PEEP. Trial registration: NCT05132933.

COVID-19 and silent hypoxemia in a minimal closed-loop model of the respiratory rhythm generator.

Silent hypoxemia, or "happy hypoxia," is a puzzling phenomenon in which patients who have contracted COVID-19 exhibit very low oxygen saturation ( SaO 2 < 80%) but do not experience discomfort in breathing. The mechanism by which this blunted response to hypoxia occurs is unknown. We have previously shown that a computational model of the respiratory neural network (Diekman et al. in J Neurophysiol 118(4):2194-2215, 2017) can be used to test hypotheses focused on changes in chemosensory inputs to the central pattern generator (CPG). We hypothesize that altered chemosensory function at the level of the carotid bodies and/or the nucleus tractus solitarii are responsible for the blunted response to hypoxia. Here, we use our model to explore this hypothesis by altering the properties of the gain function representing oxygen sensing inputs to the CPG. We then vary other parameters in the model and show that oxygen carrying capacity is the most salient factor for producing silent hypoxemia. We call for clinicians to measure hematocrit as a clinical index of altered physiology in response to COVID-19 infection.

Characterizing the Racial Discrepancy in Hypoxemia Detection in Venovenous Extracorporeal Membrane Oxygenation: An Extracorporeal Life Support Organization Registry Analysis.

PURPOSE: Skin pigmentation influences peripheral oxygen saturation (SpO2) compared to arterial saturation of oxygen (SaO2). Occult hypoxemia (SaO2 ≤ 88% with SpO2 ≥ 92%) is associated with increased in-hospital mortality in venovenous-extracorporeal membrane oxygenation (VV-ECMO) patients. We hypothesized VV-ECMO cannulation, in addition to race/ethnicity, accentuates the SpO2-SaO2 discrepancy due to significant hemolysis. METHODS: Adults (≥ 18 years) supported with VV-ECMO with concurrently measured SpO2 and SaO2 measurements from over 500 centers in the Extracorporeal Life Support Organization Registry (1/2018-5/2023) were included. Multivariable logistic regressions were performed to examine whether race/ethnicity was associated with occult hypoxemia in pre-ECMO and on-ECMO SpO2-SaO2 calculations. RESULTS: Of 13,171 VV-ECMO patients, there were 7772 (59%) White, 2114 (16%) Hispanic, 1777 (14%) Black, and 1508 (11%) Asian patients. The frequency of on-ECMO occult hypoxemia was 2.0% (N = 233). Occult hypoxemia was more common in Black and Hispanic patients versus White patients (3.1% versus 1.7%, P < 0.001 and 2.5% versus 1.7%, P = 0.025, respectively). In multivariable logistic regression, Black patients were at higher risk of pre-ECMO occult hypoxemia versus White patients (adjusted odds ratio [aOR] = 1.55, 95% confidence interval [CI] = 1.18-2.02, P = 0.001). For on-ECMO occult hypoxemia, Black patients (aOR = 1.79, 95% CI = 1.16-2.75, P = 0.008) and Hispanic patients (aOR = 1.71, 95% CI = 1.15-2.55, P = 0.008) had higher risk versus White patients. Higher pump flow rates (aOR = 1.29, 95% CI = 1.08-1.55, P = 0.005) and on-ECMO 24-h lactate (aOR = 1.06, 95% CI = 1.03-1.10, P < 0.001) significantly increased the risk of on-ECMO occult hypoxemia. CONCLUSION: SaO2 should be carefully monitored if using SpO2 during ECMO support for Black and Hispanic patients especially for those with high pump flow and lactate values at risk for occult hypoxemia.

Intermittent Hypoxemia and Bronchopulmonary Dysplasia with Pulmonary Hypertension in Preterm Infants.

Rationale: Bedside biomarkers that allow early identification of infants with bronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH) are critically important, given the higher risk of death in these infants. Objectives: We hypothesized that infants with BPD-PH have patterns of intermittent hypoxemia (IH) that differ from infants with BPD without PH. Methods: We conducted a matched case-control study of extremely preterm infants from 22 weeks 0 days to 28 weeks 6 days born between 2018 and 2020 at the University of Alabama at Birmingham. BPD-PH status was determined using echocardiographic data performed after postnatal Day 28. Physiologic data were compared between infants with BPD-PH (cases) and BPD alone (control subjects). Receiver operating characteristic (ROC) analysis estimated the predictive ability of cumulative hypoxemia, desaturation frequency, and duration of intermittent hypoxemic events in the week preceding echocardiography to discriminate between cases and control subjects. Measurements and Main Results: Forty infants with BPD-PH were compared with 40 infants with BPD alone. Infants with and without PH had a similar frequency of IH events, but infants with PH had more prolonged hypoxemic events for desaturations below 80% (7 s vs. 6 s; P = 0.03) and 70% (105 s vs. 58 s; P = 0.008). Among infants with BPD-PH, infants who died had longer hypoxemic events below 70% (145 s vs. 72 s; P = 0.01). Using the duration of hypoxemic events below 70%, the areas under the ROC curves for diagnosis of BPD-PH and death in BPD-PH infants were 0.71 and 0.77, respectively. Conclusions: Longer duration of intermittent hypoxemic events was associated both with a diagnosis of BPD-PH and with death among infants with BPD-PH.

Cardiorespiratory Monitoring Data to Predict Respiratory Outcomes in Extremely Preterm Infants.

Rationale: Immature control of breathing is associated with apnea, periodic breathing, intermittent hypoxemia, and bradycardia in extremely preterm infants. However, it is not clear if such events independently predict worse respiratory outcome. Objectives: To determine if analysis of cardiorespiratory monitoring data can predict unfavorable respiratory outcomes at 40 weeks postmenstrual age (PMA) and other outcomes, such as bronchopulmonary dysplasia at 36 weeks PMA. Methods: The Prematurity-related Ventilatory Control (Pre-Vent) study was an observational multicenter prospective cohort study including infants born at <29 weeks of gestation with continuous cardiorespiratory monitoring. The primary outcome was either "favorable" (alive and previously discharged or inpatient and off respiratory medications/O2/support at 40 wk PMA) or "unfavorable" (either deceased or inpatient/previously discharged on respiratory medications/O2/support at 40 wk PMA). Measurements and Main Results: A total of 717 infants were evaluated (median birth weight, 850 g; gestation, 26.4 wk), 53.7% of whom had a favorable outcome and 46.3% of whom had an unfavorable outcome. Physiologic data predicted unfavorable outcome, with accuracy improving with advancing age (area under the curve, 0.79 at Day 7, 0.85 at Day 28 and 32 wk PMA). The physiologic variable that contributed most to prediction was intermittent hypoxemia with oxygen saturation as measured by pulse oximetry <90%. Models with clinical data alone or combining physiologic and clinical data also had good accuracy, with areas under the curve of 0.84-0.85 at Days 7 and 14 and 0.86-0.88 at Day 28 and 32 weeks PMA. Intermittent hypoxemia with oxygen saturation as measured by pulse oximetry <80% was the major physiologic predictor of severe bronchopulmonary dysplasia and death or mechanical ventilation at 40 weeks PMA. Conclusions: Physiologic data are independently associated with unfavorable respiratory outcome in extremely preterm infants.

Sleep-disordered breathing and nocturnal hypoxemia in chronic thromboembolic pulmonary disease.

BACKGROUND AND AIMS: Sleep-disordered breathing (SDB) and nocturnal hypoxemia were known to be present in patients with chronic thromboembolic pulmonary hypertension (CTEPH), but the difference between SDB and nocturnal hypoxemia in patients who have chronic thromboembolic pulmonary disease (CTEPD) with or without pulmonary hypertension (PH) at rest remains unknown. METHODS: Patients who had CTEPH (n = 80) or CTEPD without PH (n = 40) and who had undergone sleep studies from July 2020 to October 2022 at Shanghai Pulmonary Hospital were enrolled. Nocturnal mean SpO2 (Mean SpO2) <90% was defined as nocturnal hypoxemia, and the percentage of time with a saturation below 90% (T90%) exceeding 10% was used to evaluate the severity of nocturnal hypoxemia. Logistic and linear regression analyses were performed to investigate the difference and potential predictor of SDB or nocturnal hypoxemia between CTEPH and CTEPD without PH. RESULTS: SDB was similarly prevalent in CTEPH and CTEPD without PH (P = 0.104), both characterised by obstructive sleep apnoea (OSA). Twenty-two patients with CTEPH were diagnosed with nocturnal hypoxemia, whereas only three were diagnosed with CTEPD without PH (P = 0.021). T90% was positively associated with mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance in patients with CTEPH and CTEPD without PH (P < 0.001); T90% was also negatively related to cardiac output in these patients. Single-breath carbon monoxide diffusing capacity, sex and mPAP were all correlated with nocturnal hypoxemia in CTEPH and CTEPD without PH (all P < 0.05). CONCLUSION: Nocturnal hypoxemia was worse in CTEPD with PH; T90%, but not SDB, was independently correlated with the hemodynamics in CTEPD with or without PH.

Is the time below 90% of SpO2 during sleep (T90%) a metric of good health? A longitudinal analysis of two cohorts.

BACKGROUND: Novel wireless-based technologies can easily record pulse oximetry at home. One of the main parameters that are recorded in sleep studies is the time under 90% of SpO2 (T90%) and the oxygen desaturation index 3% (ODI-3%). We assessed the association of T90% and/or ODI-3% in two different scenarios (a community-based study and a clinical setting) with all-cause mortality (primary outcome). METHODS: We included all individuals from the Sleep Heart Health Study (SHHS, community-based cohort) and Santiago Obstructive Sleep Apnea (SantOSA, clinical cohort) with complete data at baseline and follow-up. Two measures of hypoxemia (T90% and ODI-3%) were our primary exposures. The adjusted hazard ratios (HRs) per standard deviation (pSD) between T90% and incident all-cause mortality (primary outcome) were determined by adjusted Cox regression models. In the secondary analysis, to assess whether T90% varies across clinical factors, anthropometrics, abdominal obesity, metabolic rate, and SpO2, we conducted linear regression models. Incremental changes in R2 were conducted to test the hypothesis. RESULTS: A total of 4323 (56% male, median 64 years old, follow-up: 12 years, 23% events) and 1345 (77% male, median 55 years old, follow-up: 6 years, 11.6% events) patients were included in SHHS and SantOSA, respectively. Every 1 SD increase in T90% was associated with an adjusted HR of 1.18 [95% CI: 1.10-1.26] (p value < 0.001) in SHHS and HR 1.34 [95% CI: 1.04-1.71] (p value = 0.021) for all-cause mortality in SantOSA. Conversely, ODI-3% was not associated with worse outcomes. R2 explains 62% of the variability in T90%. The main contributors were baseline-mean change in SpO2, baseline SpO2, respiratory events, and age. CONCLUSION: The findings suggest that T90% may be an important marker of wellness in clinical and community-based scenarios. Although this nonspecific metric varies across the populations, ventilatory changes during sleep rather than other physiological or comorbidity variables explain their variability.

Evaluation of wakefulness electroencephalogram in OSA patients.

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.

The Effect of Continuous Positive Airway Pressure (CPAP) Therapy on Serum Caspase-3 Level in Patients with Obstructive Sleep Apnea (OSA).

INTRODUCTION: Intermittent hypoxemia has an important role in the physiopathogenesis of obstructive sleep apnea (OSA) complications. Increased apoptosis due to intermittent hypoxemia may be an important clinical entity in OSA. In this study, we aimed to evaluate caspase-3 enzyme level, which is an indirect marker of increased apoptosis in patients with OSA and to evaluate the effect of OSA treatment with continuous positive airway pressure on caspase-3 enzyme level. MATERIALS AND METHODS: This study included 141 consecutive patients admitted to the sleep-disordered breathing laboratory within 6 months. Caspase-3 was measured in routine blood samples obtained on the morning of polysomnography (PSG) performed at night. The compliance of the patients to CPAP treatment was evaluated and caspase-3 levels were checked again after treatment. RESULTS: A total of 141 patients, 39 females (27,7%) and 102 males (72,3%) were included in the study. The mean age of the patients was 49 ± 12 years (min-17, max-77). According to PSG results, OSA was detected in 95.7% (135/141) of the cases. Mild OSA was 35 (24.8%), moderate OSA 39 (27.7%) and severe OSA 61 (43.3%) cases. Median caspase-3 enzyme levels were similar in men and women in the study group. There was no statistically significant difference in hemogram parameters and caspase-3 enzyme levels between the groups divided according to the presence and severity of OSA. It was determined that caspase-3 enzyme level did not change significantly after 3 months of CPAP treatment in OSA compared to pretreatment. Caspase-3 was found to have a negative correlation with both the percentage of daily use of CPAP therapy and the percentage of CPAP device use for more than 1 h per night. It was found that the control caspase-3 level decreased statistically significantly as the percentage of daily use of CPAP therapy increased (r = -0.397, p = 0.030). It was found that the control caspase-3 level decreased statistically significantly as the percentage of CPAP therapy use for more than 1 h per night increased (r = -0.411, p = 0.024). CONCLUSION: The results of this study did not reveal a relationship between the severity of OSA and caspase-3 levels. However, blood caspase-3 levels decreased as treatment compliance increased, suggesting that CPAP treatment may correct increased apoptosis in OSA. There is a need for more comprehensive studies on this issue.

Profound hypoxemia and hypotension during posterior spinal fusion in a spinal muscular atrophy child with severe scoliosis: a case report.

BACKGROUND: Anesthesia for spinal muscular atrophy (SMA) patients undergoing spinal deformity surgery is challenging. We report an unusual case of an SMA girl who developed severe intraoperative hypoxemia and hypotension during posterior spinal fusion related with surgical positioning. CASE PRESENTATION: A 13-yr-old girl diagnosed with SMA type 2, severe kyphoscoliosis and thoracic deformity was scheduled for elective posterior spinal fusion. She developed severe hypoxemia and profound hypotension intraoperatively in the prone position with surgical table tilted 45° to the right. Though transesophageal echocardiography (TEE) could not be performed due to limited mouth opening, her preoperative computed tomography revealed a severely distorted thoracic cavity with much reduced volume of the right side. A reasonable explanation was when the surgeons performed surgical procedure with the tilted surgical table, the pressure was directly put on the shortest diameter of the significantly deformed thoracic cavity, causing severe compression of the pulmonary artery, resulting in both hypoxemia and hypotension. The patient stabilized when the surgical table was tilted back and successfully went through the surgery in the leveled prone position. CONCLUSIONS: Spinal fusion surgery is beneficial for SMA patients in preventing scoliosis progression and improving ventilation. However, severe scoliosis and thoracic deformities put them at risk of both hemodynamic and respiratory instability during surgical positioning. When advanced monitoring like TEE is not practical intraoperatively, preoperative imaging may help with differential diagnosis, and guide the surgical positioning to minimize mechanical compression of the thoracic cavity, thereby helping the patient complete the surgery safely.

The association of vaping and electronic cigarette use with postoperative hypoxemia and respiratory complications: a retrospective cohort analysis.

PURPOSE: Initially introduced as a safer alternative to smoking, electronic cigarettes (e-cigarettes) and vaping have since been associated with lung injury. Nevertheless, there is limited perioperative data on their potential contribution to the harmful effects of mechanical ventilation on the lungs. We hypothesized that, in adults undergoing noncardiothoracic surgeries, preoperative vaping/e-cigarette use is associated with hypoxemia during the first postoperative hour, and with an increased incidence of intraoperative and postoperative pulmonary complications. METHODS: We conducted a retrospective cohort study in which we included patients reporting as vapers/e-cigarette users within one year before surgery as the exposure group, and nonvapers as the control group. The primary outcome was the time-weighted average (TWA) SpO2/FIO2 ratio in the postanesthesia care unit during the first postoperative hour. The secondary outcome was a composite of intraoperative and postoperative pulmonary complications until discharge. We used entropy balancing to adjust for confounding, and fit weighted linear regression and logistic regression models to estimate treatment effects. RESULTS: A total of 110,940 patients met the inclusion criteria, and 1,941 of these were vapers/e-cigarette users. The average treatment effect on the treated for TWA SpO2/FIO2 ratio (N = 109,217) was estimated to be a mean difference of 4 (95% confidence interval [CI], 1 to 8; P = 0.007). This is equivalent to a 4% change in SpO2 at a 30% FIO2 (or at a fixed FIO2). The difference was statistically significant. The average treatment effect on the treated for experiencing intraoperative and postoperative pulmonary complications (N = 110,940) was an odds ratio of 1.04 (95% CI, 0.71 to 1.54; P = 0.84). CONCLUSION: Vaping/e-cigarette use was neither associated with clinically significant hypoxemia during the first hour in the postanesthesia care unit nor with an increase in pulmonary complications. Nevertheless, our findings cannot definitively exclude the deleterious effects of vaping and e-cigarette use on the lungs, and anesthesiologists should consider potential perioperative complications.

RéSUMé: OBJECTIF: Initialement introduites comme une alternative plus sécuritaire au tabagisme, les cigarettes électroniques et le vapotage ont depuis été associés à des lésions pulmonaires. Néanmoins, il existe peu de données périopératoires concernant leur contribution potentielle aux effets nocifs de la ventilation mécanique sur les poumons. Nous avons émis l'hypothèse que, chez les adultes bénéficiant de chirurgies non cardiothoraciques, l'utilisation préopératoire de vapotage/de cigarette électronique était associée à une hypoxémie au cours de la première heure postopératoire et à une incidence accrue de complications pulmonaires peropératoires et postopératoires. MéTHODE: Nous avons mené une étude de cohorte rétrospective dans laquelle nous avons inclus les patient·es déclarant avoir vapoté ou utilisé des cigarettes électroniques dans l'année précédant la chirurgie comme groupe d'exposition, et les personnes ne vapotant pas comme groupe témoin. Le critère d'évaluation principal était le rapport de SpO2/FIO2 moyen pondéré dans le temps en salle de réveil pendant la première heure postopératoire. Le critère d'évaluation secondaire était un mélange de complications pulmonaires peropératoires et postopératoires jusqu'au congé de l'hôpital. Nous avons utilisé l'équilibrage d'entropie pour ajuster les facteurs de confusion et ajusté les modèles de régression linéaire pondérée et de régression logistique pour estimer les effets du traitement. RéSULTATS: Au total, 110 940 patient·es répondaient aux critères d'inclusion, dont 1941 étaient des vapoteurs ou vapoteuses/utilisaient des cigarettes électroniques. L'effet moyen du traitement sur le rapport de SpO2/FIO2 moyen pondéré dans le temps des personnes traitées (N = 109 217) a été estimé à une différence moyenne de 4 (intervalle de confiance [IC] à 95 %, 1 à 8; P = 0,007). Cela équivaut à une variation de 4 % de la SpO2 à 30% FIO2 (ou à une FIO2 fixe). La différence était statistiquement significative. L'effet moyen du traitement sur les personnes traitées pour des complications pulmonaires peropératoires et postopératoires (N = 110 940) était un rapport de cotes de 1,04 (IC 95 %, 0,71 à 1,54; P = 0,84). CONCLUSION: L'utilisation du vapotage et de la cigarette électronique n'était associée ni à une hypoxémie cliniquement significative au cours de la première heure en salle de réveil, ni à une augmentation des complications pulmonaires. Néanmoins, nos résultats ne peuvent exclure de manière définitive les effets délétères du vapotage et de l'utilisation de la cigarette électronique sur les poumons, et les anesthésiologistes devraient tenir compte des complications périopératoires potentielles.

High-flow nasal cannula oxygen reduced hypoxemia in patients undergoing gastroscopy under general anesthesia at ultra-high altitude: a randomized controlled trial.

BACKGROUND: Hypoxemia can occur in people at ultra-high altitude (above 3500 m) even at rest, and patients undergoing gastroscopy under general anesthesia have higher risk of hypoxemia. Supplementary oxygen via standard nasal cannula (SNC) is the standard of care for most patients who undergo gastroscopy under general anesthesia, which provides oxygen flow up to 15 L/min. High-flow nasal cannula (HFNC) could deliver oxygen at a rate up to 60 L/min, which is recommended by the American Society of Anesthesiologists Practice Guidelines. We speculated that the benefit with HFNC is more prominent in high-altitude areas, and aimed to compare the incidence of hypoxemia during gastroscopy under general anesthesia at ultra-high altitude with oxygen supply via either HFNC or SNC. METHODS: The trial was registered at at Chinese Clinical Trial Registry (ChiCTR2100045513; date of registration on 18/04/2021). Adult patients undergoing gastroscopy with anesthesia (estimated duration of anesthesia at ≥ 15 min) were randomized at a 1:1 ratio to receive HFNC oxygen or SNC oxygen. The primary outcome was hypoxemia (SpO2 < 90% for any duration). Secondary outcomes included severe hypoxemia (SpO2 < 75% for any duration or SpO2 < 90% but ≥ 75% for ≥ 60 s) and hypotension, as defined by reduction of mean arterial blood pressure by ≥ 25% from the baseline. RESULTS: A total of 262 patients were enrolled: 129 in the HFNC group and 133 in the SNC group. All patients received the designated intervention. Student's t-test, Mann-Whitney U test and χ2 test were employed in the study. The rate of hypoxemia was 9.3% (12/129) in the HFNC group versus 36.8% (49/133) in the SNC group [risk ratio (95% confidence interval): 0.25(0.14-0.45); P < 0.001). The HFNC group also had lower rate of severe hypoxemia [0.0% (0/129) versus 11.3% (15/133); risk ratio (95% confidence interval): 0.03(0.00-0.55); P < 0.001, respectively]. The rate of hypotension did not differ between the 2 groups [22.5% (29/129) in HFNC group versus 21.1% (28/133) in SNC group; risk ratio (95% confidence interval): 1.07(0.67-1.69) ; P = 0.779]. CONCLUSION: HFNC oxygen reduced the incidence of hypoxemia during anesthesia in adult patients undergoing gastroscopy at ultra-high altitude.

Oxygen reserve index vs. peripheral oxygen saturation for the prediction of hypoxemia in morbidly obese patients: a prospective observational study.

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. GOV IDENTIFIER: NCT05480748 registered 2022-07-29.

Hypoxemia and its clinical predictors among children with respiratory distress admitted to the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia.

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