Desaturation Severity Research Articles

Hypoxaemic load in sleep apnoea is associated with acute changes in T-wave amplitude.

Obstructive sleep apnoea (OSA) imposes significant stress on the cardiovascular system and the heart. While long-term cardiac effects are understood, the immediate impact of hypoxaemia on the heart's electrophysiology lacks understanding. Our study aims to explore desaturation severity on cardiovascular repolarisation. We retrospectively analysed ECGs from full diagnostic polysomnographies from 492 patients with suspected OSA. The analyses were conducted before, during and after 9137 nocturnal apnoea- or hypopnoea-related desaturations. The mean and sd of T-wave amplitude change from the baseline level to the level during and after desaturations (ΔTamp_mean and ΔTamp_SD) were calculated. To investigate the modulatory effects of desaturation severity, the data were divided into subgroups based on the desaturation duration (Tdes; 10 s≤Tdes<20 s, 20 s≤Tdes<30 s, 30 s≤Tdes<45 s and Tdes≥45 s) and magnitude of blood oxygen saturation drop (change in peripheral oxygen saturation (ΔS pO2 ); 3%≤ΔS pO2 <4.5%, 4.5%≤ΔS pO2 <6%, 6%≤ΔS pO2 <7.5% and ΔS pO2 ≥7.5%) for men and women. Desaturations caused significant (p<0.01) changes in ΔTamp_mean during and after desaturations. In men, the median ΔTamp_mean during and after deep (ΔS pO2 ≥7.5%) desaturations were 21 µV and 24 µV, respectively. In women, the median ΔTamp_mean in deep desaturations was 15 µV during and 21 µV after desaturations. Similarly, the ΔTamp_SD increased during and after deep desaturations. In regression analysis, the desaturation depth was an independent predictor for ventricular repolarisation instability. We found an association between the severity of nocturnal desaturations and cardiac repolarisation instability. These findings hold particular importance, as repolarisation instability has been linked with cardiovascular morbidity and could potentially serve as a trigger for arrhythmias and sudden cardiac death.

Comparing electrophysiological biomarkers and circulating cardiac biomarkers in predicting cardiovascular mortality and all-cause mortality in the akershus sleep apnea (ASAP) epidemiological cohort

Abstract Background Major cardiovascular events (MACE) and mortality in obstructive sleep apnea (OSA) patients have been frequently reported. However, there is an ongoing debate regarding biomarkers predicting MACE and mortality in OSA. The Apnoea Hypopnea Index (AHI) has been used to assess the severity of Obstructive Sleep Apnea (OSA) despite poor association with adverse outcomes in OSA patients. Novel electrophysiological biomarkers (EPBs) such as desaturation parameters have been suggested as an alternative, and have been reported to be stronger predictors of cardiovascular mortality and heart failure. However, circulating cardiac biomarkers (CCBs) remain strong predictors of mortality and cardiovascular disease in the general population. Purpose To detect the incidence of MACE and all-cause mortality after a median of 13.8 years follow-up in individuals with OSA, and to assess the ability of CCBs and EPBs to predict MACE and all-cause mortality. Methods Polysomnography and CCB analyses (cardiac troponin I (cTnI) and T (cTnT)) were conducted in 459 participants in the Akershus Sleep APnea study (ASAP) between 2006-2008. EPBs evaluated were the AHI, oxygen desaturation index (ODI), desaturation duration (DesDur) and desaturation severity (DesSev). Cox regression and cumulative incidence Kaplan-Meier curves were used for survival analysis. Comparison of EPBs and CCBs in predicting MACE and all-cause mortality was assessed by the area under the curve (AUC). Results 77 and 35 participants reached the endpoint of MACE and all-cause mortality, respectively. In the adjusted cox regression model, cTnI and cTnT were significantly associated with MACE with a hazard ratios of 1.84 [95% Confidence interval [CI], 1.43, 2.37] and 1.52 [1.05, 2.20], respectively. Association of these CCBs with all-cause mortality was with a hazard ratios of 2.02 [1.38, 2.96] and 1.75 [1.05, 2.92], respectively. Moreover, cTnI had the highest AUC of 0.77 and 0.75 in predicting MACE and all-cause mortality. Notably, high AHI, ODI, DesDur and DesSev (upper quartile) increased the cumulative incidence of MACE and all-cause mortality in the subgroup of patients with high CCBs (upper quartile) compared to the subgroup of patients with high CCBs and low EPBs (lower quartile). Conclusion CCBs were more associated with all-cause mortality and MACE than EPBs in ASAP epidemiological cohort. However, the tested EPBs are important biomarkers that increase CCBs prediction of both MACE and all-cause mortality.

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 (β = 8.05, p < 0.01), FallSev (β = 6.48, p = 0.02), RecovSev (β = 9.13, p < 0.01), and Oxygen Desaturation Index (β = 12.29, p < 0.01) were associated with increased RTs only in males. Conversely, the Arousal Index (β = 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.

Obstructive Sleep Apnea Patients With Atrial Arrhythmias Suffer From Prolonged Recovery From Desaturations

We aimed to investigate how acute and long-term effects of atrial arrhythmias affect the desaturation severity and characteristics determined from the oxygen saturation signal in OSA patients. 520 suspected OSA patients were included in retrospective analyses. Eight desaturation area and slope parameters were calculated from blood oxygen saturation signals recorded during polysomnographic recordings. Patients were grouped based on whether they had previously diagnosed atrial arrhythmia (i.e., atrial fibrillation (AFib) or atrial flutter) or not. Furthermore, patients with a previous atrial arrhythmia diagnosis were sub-grouped based on whether they had continuous AFib or sinus rhythm during the polysomnographic recordings. Empirical cumulative distribution functions and linear mixed models were utilized to investigate the connection between diagnosed atrial arrhythmia and the desaturation characteristics. Patients with previous atrial arrhythmia diagnosis had greater desaturation recovery area when the 100% oxygen saturation baseline reference was considered (β=0.150-0.127, p≤0.039) and more gradual recovery slopes (β=-0.181- -0.199, p<0.004) than patients without a previous atrial arrhythmia diagnosis. Furthermore, patients with AFib had more gradual oxygen saturation fall and recovery slopes than patients with sinus rhythm. Desaturation recovery characteristics in the oxygen saturation signal contains essential information about the cardiovascular response to hypoxemic periods. More comprehensive consideration of the desaturation recovery section could provide more detailed information about OSA severity, for example when developing new diagnostic parameters.

Is obstructive sleep apnea a circadian rhythm disorder?

Obstructive sleep apnea is the most common sleep-related breathing disorder worldwide and remains underdiagnosed. Its multiple associated comorbidities contribute to a decreased quality of life and work performance as well as an increased risk of death. Standard treatment seems to have limited effects on cardiovascular and metabolic aspects of the disease, emphasising the need for early diagnosis and additional therapeutic approaches. Recent evidence suggests that the dysregulation of circadian rhythms, processes with endogenous rhythmicity that are adjusted to the environment through various cues, is involved in the pathogenesis of comorbidities. In patients with obstructive sleep apnea, altered circadian gene expression patterns have been demonstrated. Obstructive respiratory events may promote circadian dysregulation through the effects of sleep disturbance and intermittent hypoxia, with subsequent inflammation and disruption of neural and hormonal homeostasis. In this review, current knowledge on obstructive sleep apnea, circadian rhythm regulation, and circadian rhythm sleep disorders is summarised. Studies that connect obstructive sleep apnea to circadian rhythm abnormalities are critically evaluated. Furthermore, pathogenetic mechanisms that may underlie this association, most notably hypoxia signalling, are presented. A bidirectional relationship between obstructive sleep apnea and circadian rhythm dysregulation is proposed. Approaching obstructive sleep apnea as a circadian rhythm disorder may prove beneficial for the development of new, personalised diagnostic, therapeutic and prognostic tools. However, further studies are needed before the clinical approach to obstructive sleep apnea includes targeting the circadian system.

Desaturation event scoring criteria affect the perceived severity of nocturnal hypoxic load

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

ABOSA – Freely available automatic blood oxygen saturation signal analysis software: Structure and validation

Background and objectiveMany sleep recording software used in clinical settings have some tools to automatically analyze the blood oxygen saturation (SpO2) signal by detecting desaturations. However, these tools are often inadequate for scientific research as they do not provide SpO2 signal-based parameters which are superior in the estimation of sleep apnea severity and related medical consequences. In addition, these software require expensive licenses and they lack batch analysis tools. Thus, we developed the first freely available automatic blood oxygen saturation analysis software (ABOSA) that provides sophisticated SpO2 signal-based parameters and enables batch analysis of large datasets. MethodsABOSA was programmed with MATLAB. ABOSA automatically detects desaturation and recovery events from the SpO2 signals (EDF files) and calculates numerous parameters, such as oxygen desaturation index (ODI) and desaturation severity (DesSev). The accuracy of the ABOSA software was evaluated by comparing its desaturation scorings to manual scorings in Kuopio (n = 1981) and Loewenstein (n = 930) sleep apnea patient datasets. Validation was performed in a second-by-second manner by calculating Matthew's correlation coefficients (MCC) and median differences in parameter values. Finally, the performance of the ABOSA software was compared to two commercial software, Noxturnal and Profusion, in 100 patient subpopulations. As Noxturnal or Profusion does not calculate novel desaturation parameters, these were calculated with custom-made functions. ResultsThe agreements between ABOSA and manual scorings were great in both Kuopio (MCC = 0.801) and Loewenstein (MCC = 0.898) datasets. However, ABOSA slightly overestimated the desaturation parameter values. The median differences in ODIs were 0.8 (Kuopio) and 0.0 (Loewenstein) events/h. Similarly, the median differences in DesSevs were 0.02 (Kuopio) and 0.01 (Loewenstein) percentage points. In a second-by-second analysis, ABOSA performed very similarly to Noxturnal and Profusion software in both Kuopio (MCCABOSA = 0.807, MCCNoxturnal = 0.807, MCCProfusion = 0.811) and Loewenstein (MCCABOSA = 0.904, MCCNoxturnal = 0.911, MCCProfusion = 0.871) datasets. Based on Noxturnal and Profusion scorings, the desaturation parameter values were similarly overestimated compared to ABOSA. ConclusionsABOSA is an accurate and freely available software that calculates both traditional clinical parameters and novel parameters, provides a detailed characterization of desaturation and recovery events, and enables batch analysis of large datasets. These are features that no other software currently provides making ABOSA uniquely suitable for scientific research use.

Impact of Desaturation Patterns versus Apnea-Hypopnea Index in the Development of Cardiovascular Comorbidities in Obstructive Sleep Apnea Patients.

Various phenotypes of obstructive sleep apnea (OSA) have been recently described and are poorly assessed by the commonly used polysomnographic indices, such as the apnea–hypopnea index and oxygen desaturation index. Nocturnal hypoxemia is the hallmark of OSA and new quantitative markers, as hypoxic burden or desaturation severity, have been shown to be associated with cardiovascular (CV) mortality. The purpose of this overview is to review the endophenotypical and clinical characteristics of OSA, the current metrics, and to analyze different measurements of hypoxemia in OSA to predict the cardiovascular impact (eg hypoxic burden). Potential interest of multidimensional models to classify OSA, such as BAVENO classification, is also discussed, with the goal of focusing on specific endophenotypes that are likely to develop CV comorbidities, in order to guide clinicians to more aggressive management of OSA in these individuals.

Obstructive sleep apnoea-related respiratory events and desaturation severity are associated with the cardiac response.

BackgroundObstructive sleep apnoea (OSA) causes, among other things, intermittent blood oxygen desaturations, increasing the sympathetic tone. Yet the effect of desaturations on heart rate variability (HRV), a simple and noninvasive method for assessing sympathovagal balance, has not been comprehensively studied. We aimed to study whether desaturation severity affects the immediate HRV.MethodsWe retrospectively analysed the electrocardiography signals in 5-min segments (n=39 132) recorded during clinical polysomnographies of 642 patients with suspected OSA. HRV parameters were calculated for each segment. The segments were pooled into severity groups based on the desaturation severity (i.e. the integrated area under the blood oxygen saturation curve) and the respiratory event rate within the segment. Covariate-adjusted regression analyses were performed to investigate possible confounding effects.ResultsWith increasing respiratory event rate, the normalised high-frequency band power (HFNU) decreased from 0.517 to 0.364 (p<0.01), the normalised low-frequency band power (LFNU) increased from 0.483 to 0.636 (p<0.01) and the mean RR interval decreased from 915 to 869 ms (p<0.01). Similarly, with increasing desaturation severity, the HFNU decreased from 0.499 to 0.364 (p<0.01), the LFNU increased from 0.501 to 0.636 (p<0.01) and the mean RR interval decreased from 952 to 854 ms (p<0.01). Desaturation severity-related findings were confirmed by considering the confounding factors in the regression analyses.ConclusionThe short-term HRV response differs based on the desaturation severity and the respiratory event rate in patients with suspected OSA. Therefore, a more detailed analysis of HRV and desaturation characteristics could enhance OSA severity estimation.

Desaturation severity affects OSA-related changes in short-term heart rate variability

Desaturation severity affects OSA-related changes in short-term heart rate variability

Novel oxygen desaturation parameters are associated with cardiac troponin I: Data from the Akershus Sleep Apnea Project.

Novel diagnostic markers for obstructive sleep apnea beyond the apnea-hypopnea index (AHI) have been introduced. There are no studies on their association with markers of subclinical myocardial injury. We assessed the association between novel desaturation parameters and elevated cardiac troponin I and T. Participants with polysomnography (498) from the Akershus Sleep Apnea study were divided into normal and elevated biomarker groups based on sex-specific concentration thresholds (cardiac troponin I: ≥4ng/L for women, ≥6ng/L for men; and cardiac troponin T: ≥7ng/L for women, ≥8ng/L for men). Severity of obstructive sleep apnea was evaluated with the AHI, oxygen desaturation index, total sleep time with oxygen saturation below 90% (T90), lowest oxygen saturation (Min SpO2 %), and novel oxygen desaturation parameters: desaturation duration and desaturation severity. How the AHI and novel desaturation parameters predicted elevated cardiac troponin I and cardiac troponin T levels was assessed by the area under the curve (AUC). Based on multivariable-adjusted linear regression, the AHI (β=0.004, p=0.012), desaturation duration (β=0.007, p=0.004), and desaturation severity (β=0.147, p=0.002) were associated with cardiac troponin I levels but not cardiac troponin T. T90 was associated with cardiac troponin I (β=0.006, p=0.009) and cardiac troponin T (β=0.005, p=0.007). The AUC for the AHI 0.592 (standard error 0.043) was not significantly different from the AUC of T90 (SD 0.640, p=0.08), desaturation duration 0.609 (SD0.044, p=0.42) or desaturation severity 0.616 (SD 0.043, p=0.26) in predicting myocardial injury as assessed by cardiac troponin I. Oxygen desaturation parameters and the AHI were associated with cardiac troponin I levels but not cardiac troponin Tlevels. Novel oxygen desaturation parameters did not improve the prediction of subclinical myocardial injury compared to the AHI.

Neurally adjusted ventilatory assist in ventilated very preterm infants: A crossover study

To assess the effects of neurally adjusted ventilatory assist (NAVA) ventilation on oxygenation and respiratory parameters in preterm infants. An observational crossover study with a convenience sample of 19 infants born before 30 gestational weeks. Study parameters were recorded during 3-h periods of both NAVA and conventional ventilation. The proportion of time peripheral oxygen saturation (SpO2 ) and cerebral regional oxygen saturation (cRSO2 ) were within their target ranges, plus the number and severity of desaturation episodes were analyzed. In addition, electrical activity of the diaphragm (Edi), neural respiratory rates, and peak inspiratory pressures (PIPs) were recorded. Infants were born at a median age of 264/7 gestational weeks (range: 230/7 -293/7 ); the study was performed at a median age of 20 days (range: 1-82). The proportion of time SpO2 was within the target range, the number of peripheral desaturations or cRSO2 did not differ between the modes. However, the desaturation severity index was lower (131 vs. 152; p = .03) and fewer manual supplemental oxygen adjustments (1.3 vs. 2.2/h; p = .006) were needed during the period of NAVA ventilation following conventional ventilation. The mean Edi (8.1 vs. 11.4 µV; p < .006) and PIP values (14.9 vs. 19.1; p < .001) were lower during the NAVA mode. Although NAVA ventilation did not increase the proportion of time with optimal saturation, it was associated with decreased diaphragmatic activity, lower PIPs, less severe hypoxemic events, and fewer manual oxygen adjustments in very preterm infants.

Diabetes and cardiovascular diseases are associated with the worsening of intermittent hypoxaemia.

Intermittent hypoxaemia is a risk factor for numerous diseases. However, the reverse pathway remains unclear. Therefore, we investigated whether pre-existing hypertension, diabetes or cardiovascular diseases are associated with the worsening of intermittent hypoxaemia. Among the included 2,535 Sleep Heart Health Study participants, hypertension (n=1,164), diabetes (n=170) and cardiovascular diseases (n=265) were frequently present at baseline. All participants had undergone two polysomnographic recordings approximately 5.2years apart. Covariate-adjusted linear regression analyses were utilized to investigate the difference in the severity of intermittent hypoxaemia at baseline between each comorbidity group and the group of participants free from all comorbidities (n=1,264). Similarly, we investigated whether the pre-existing comorbidities are associated with the progression of intermittent hypoxaemia. Significantly higher oxygen desaturation index (β=1.77 [95% confidence interval: 0.41-3.13], p=0.011), desaturation severity (β=0.07 [95% confidence interval: 0.00-0.14], p=0.048) and desaturation duration (β=1.50 [95% confidence interval: 0.31-2.69], p=0.013) were observed in participants with pre-existing cardiovascular diseases at baseline. Furthermore, the increase in oxygen desaturation index (β=3.59 [95% confidence interval: 1.78-5.39], p<0.001), desaturation severity (β=0.08 [95% confidence interval: 0.02-0.14], p=0.015) and desaturation duration (β=2.60 [95% confidence interval: 1.22-3.98], p<0.001) during the follow-up were higher among participants with diabetes. Similarly, the increase in oxygen desaturation index (β=2.73 [95% confidence interval: 1.15-4.32], p=0.001) and desaturation duration (β=1.85 [95% confidence interval: 0.62-3.08], p=0.003) were higher among participants with cardiovascular diseases. These results suggest that patients with pre-existing diabetes or cardiovascular diseases are at increased risk for an expedited worsening of intermittent hypoxaemia. As intermittent hypoxaemia is an essential feature of sleep apnea, these patients could benefit from the screening and follow-up monitoring of sleep apnea.

Longer and Deeper Desaturations Are Associated With the Worsening of Mild Sleep Apnea: The Sleep Heart Health Study.

Study ObjectivesObesity, older age, and male sex are recognized risk factors for sleep apnea. However, it is unclear whether the severity of hypoxic burden, an essential feature of sleep apnea, is associated with the risk of sleep apnea worsening. Thus, we investigated our hypothesis that the worsening of sleep apnea is expedited in individuals with more severe desaturations.MethodsThe blood oxygen saturation (SpO2) signals of 805 Sleep Heart Health Study participants with mild sleep apnea [5 ≤ oxygen desaturation index (ODI) < 15] were analyzed at baseline and after a mean follow-up time of 5.2 years. Linear regression analysis, adjusted for relevant covariates, was utilized to study the association between baseline SpO2-derived parameters and change in sleep apnea severity, determined by a change in ODI. SpO2-derived parameters, consisting of ODI, desaturation severity (DesSev), desaturation duration (DesDur), average desaturation area (avg. DesArea), and average desaturation duration (avg. DesDur), were standardized to enable comparisons between the parameters.ResultsIn the group consisting of both men and women, avg. DesDur (β = 1.594, p = 0.001), avg. DesArea (β = 1.316, p = 0.004), DesDur (β = 0.998, p = 0.028), and DesSev (β = 0.928, p = 0.040) were significantly associated with sleep apnea worsening, whereas ODI was not (β = −0.029, p = 0.950). In sex-stratified analysis, avg. DesDur (β = 1.987, p = 0.003), avg. DesArea (β = 1.502, p = 0.024), and DesDur (β = 1.374, p = 0.033) were significantly associated with sleep apnea worsening in men.ConclusionLonger and deeper desaturations are more likely to expose a patient to the worsening of sleep apnea. This information could be useful in the planning of follow-up monitoring or lifestyle counseling in the early stage of the disease.

PREVALENCE, CHARACTERISTICS, AND ASSOCIATION OF OBSTRUCTIVE SLEEP APNEA (OSA) AND INTERMITTENT HYPOXEMIA WITH COGNITIVE FUNCTION IN PATIENTS WITH MILD-MODERATE ALZHEIMER DISEASE (AD)

TYPE: Abstract Publication TOPIC: Sleep Disorders PURPOSE: Analysis of several prospective populational studies had indicated that those subjects with OSA were more likely to develop cognitive impairment and AD. However, poor is known about the implications of OSA and intermittent hypoxemia in patients with early AD. The aim of this work was to evaluate the prevalence of OSA in patients with a new diagnosis of mild-moderate AD and to evaluate the repercussion on cognitive function. METHODS: We included prospectively 128 subjects with new diagnosis of AD, stratified by their apnea/hypoapnea index evaluated by polysomnography. Subjects were studied by means of a sleep questionnaire that included the Epworth scale and extensive neuropsychological battery RESULTS: Prevalence of OSA was 90,6%. According the severity of OSA, 23% were mild, 29% moderate and 39% severe. The score on the Epworth scale was 5.66, without significant differences between groups (p>0.05). We evaluated the characteristics of cognition according to the severity of OSA. No statistically significant differences were observed. Given oxygen desaturation severity, we observed that patients with severe intermittent hypoxemia showed better cognitive performances in overall items related to verbal memory (Table 1) When we analysed intermittent hypoxia data by gender groups, all differences were observed in female group CONCLUSIONS: High prevalence of no diagnosed OSA in patients with a new diagnosis of AD. This prevalence is not related with an increase of diurnal somnolence. Severe intermittent hypoxemia seems related with a better neuropsychological profile in several cognitive domains. CLINICAL IMPLICATIONS: Maybe, chronic hypoxia throw the phenomenon of ischemic tolerance could have a benefit effect. DISCLOSURE: No significant relationships. KEYWORDS: OSA, Intermittent hypoxia, Alzheimer Disease

0593 Hypoxemia During Sleep Disordered Breathing and Cardiovascular Disease: A Comparison of Different Oxygen Desaturation Measures

Abstract Introduction The apnea-hypopnea index has been used to characterize obstructive sleep apnea (OSA) severity. However, this metric is limited in providing information about cardiovascular disease (CVD) risk. Recent studies proposed alternative metrics that capture frequency, duration, depth, and combinations of duration and depth of hypoxemia. This study provides a systematic evaluation of the association between conventional or novel nocturnal hypoxemia metrics and the incidence of CVD and CV mortality in the Sleep Heart Health Study (SHHS). Methods We used data from 5,042 participants of the SHHS. Over 10.7 years, there were 1,312 (26.0%) incident CVD events and 359 (7.1%) CV deaths. We calculated standardized (z-scored) values of eight nocturnal hypoxemia indices, including conventional (e.g., oxygen desaturation index) and novel metrics (e.g., hypoxic burden, respiratory event-related area under desaturation curve and desaturation severity, corresponding to alternative quantitative measurements looking at the shape of each desaturation event). The association between each metric and incidence of CVD or CV mortality was evaluated using Cox proportional hazards models. Age, sex, body mass index, race, ethnicity, smoking, total sleep time, number of respiratory events, and prevalent CVD at baseline were used as covariates. Hazard ratios (HR) are presented as the effect of one standard deviation increase in each correponding metric. Results In unadjusted models, all nocturnal hypoxemia indices were associated with increased incidence of CVD and CV mortality. In adjusted models, longer average desaturation duration was associated with lower CVD incidence (HR[95%CI]=0.93[0.86-0.99];p=0.034), higher hypoxic burden with increased CV mortality (HR[95%CI]=1.22[1.04-1.43];p=0.017), and higher % sleep time with oxygen saturation less than 90% (Tlt90%) with increased CV mortality (HR[95%CI]=1.12[1.00-1.26];p=0.040). Conclusion Different metrics of nocturnal hypoxemia derived from polysomnography were associated with CV risk in the SHHS. However, after covariate adjustment, only shorter average desaturation duration, and higher hypoxic burden and Tlt90% were independent CV risk factors. Support AASM Foundation (194-SR-18,188-SR-17); American Heart Association (19CDA34660137); NIH (U01HL53940,U01HL53941,U01HL63463,U01HL53937, U01HL53938,U01HL53916,U01HL53934,U01HL63429,U01HL53931,HL114473, P01HL094307,HL134015,R35HL135818,1R21HL145492-01,R01HL102321,R01HL128658); The State Research Funding (KUH: 5041767, 5041768; TUH: VTR3242, VTR3228, EVO2089), Academy of Finland (313697, 323536), Business Finland (5133/31/2018), Respiratory Foundation of Kuopio Region, Tampere Tuberculosis Foundation, Research Foundation of Pulmonary Diseases, Foundation of Finnish Anti-Tuberculosis Association.

Severe desaturations increase psychomotor vigilance task-based median reaction time and number of lapses in obstructive sleep apnoea patients.

Current diagnostic parameters estimating obstructive sleep apnoea (OSA) severity have a poor connection to the psychomotor vigilance of OSA patients. Thus, we aimed to investigate how the severity of apnoeas, hypopnoeas and intermittent hypoxaemia is associated with impaired vigilance.We retrospectively examined type I polysomnography data and corresponding psychomotor vigilance tasks (PVTs) of 743 consecutive OSA patients (apnoea–hypopnoea index (AHI) ≥5 events·h−1). Conventional diagnostic parameters (e.g. AHI and oxygen desaturation index (ODI)) and novel parameters (e.g. desaturation severity and obstruction severity) incorporating duration of apnoeas and hypopnoeas as well as depth and duration of desaturations were assessed. Patients were grouped into quartiles based on PVT outcome variables. The odds of belonging to the worst-performing quartile were assessed. Analyses were performed for all PVT outcome variables using binomial logistic regression.A relative 10% increase in median depth of desaturations elevated the odds (ORrange 1.20–1.37, p<0.05) of prolonged mean and median reaction times as well as increased lapse count. Similarly, an increase in desaturation severity (ORrange 1.26–1.52, p<0.05) associated with prolonged median reaction time. Female sex (ORrange 2.21–6.02, p<0.01), Epworth Sleepiness Scale score (ORrange 1.05–1.07, p<0.01) and older age (ORrange 1.01–1.05, p<0.05) were significant risk factors in all analyses. In contrast, increases in conventional AHI, ODI and arousal index were not associated with deteriorated PVT performance.These results show that our novel parameters describing the severity of intermittent hypoxaemia are significantly associated with increased risk of impaired PVT performance, whereas conventional OSA severity and sleep fragmentation metrics are not. These results underline the importance of developing the assessment of OSA severity beyond the AHI.

Nocturnal Hypoxemia Impacts Right Ventricle Diastolic Function in Obstructive Sleep Apnea: A Retrospective Observational Study.

Obstructive sleep apnea (OSA), although a growing healthcare problem and documented risk factor for cardiovascular diseases, is still under-diagnosed in cardiac patients. To investigate the correlation between OSA and echocardiographic parameters of right ventricle diastolic (RVD) dysfunction, in particular trans-tricuspid E-wave deceleration time (EDT), we retrospectively analyzed data of 103 pure (comorbidity-free) OSA patients with comprehensive echocardiographic examination (ETT). Apnea/hypopnea index (AHI), oxygen desaturation index (ODI), mean nighttime oxyhemoglobin saturation (SpO2), time elapsed with SpO2 < 90% (T90) and mean peak desaturation of nocturnal events (Mdes, graded as mild, medium or severe) were compared with echocardiographic parameters. We found RVD dysfunction present in 58.3% of patients. Altered EDT correlated significantly with mean SpO2, T90, and Mdes (p < 0.01, all). Nocturnal desaturators had a significantly worse EDT than non-desaturators (p = 0.027) and a higher risk of prolonged EDT (odds ratio, OR = 2.86). EDT differed significantly according to Mdes severity (p = 0.005) with a higher risk of prolonged EDT in medium/severe vs. mild Mdes (OR = 3.44). EDT detected the presence of RVD dysfunction in 58.3% of our pure OSA patients. It correlated poorly with AHI severity but strongly with nocturnal desaturation severity, independently of age. This ETT marker may be useful for deciding appropriate diagnostic and therapeutic strategies.

Severity of Desaturations Reflects OSA-Related Daytime Sleepiness Better Than AHI.

The aim was to investigate how the severity of apneas, hypopneas, and related desaturations is associated with obstructive sleep apnea (OSA)-related daytime sleepiness. Multiple Sleep Latency Tests and polysomnographic recordings of 362 patients with OSA were retrospectively analyzed and novel diagnostic parameters (eg, obstruction severity and desaturation severity), incorporating severity of apneas, hypopneas, and desaturations, were computed. Conventional statistical analysis and multivariate analyses were utilized to investigate connection of apnea-hypopnea index (AHI), oxygen desaturation index (ODI), conventional hypoxemia parameters, and novel diagnostic parameters with mean daytime sleep latency (MSL). In the whole population, 10% increase in values of desaturation severity (risk ratio = 2.01, P < .001), obstruction severity (risk ratio = 2.18, P < .001) and time below 90% saturation (t90%) (risk ratio = 2.05, P < .001) induced significantly higher risk of having mean daytime sleep latency ≤ 5 minutes compared to 10% increase in AHI (risk ratio = 1.63, P < .05). In severe OSA, desaturation severity had significantly (P < .02) stronger negative correlation (ρ = -.489, P < .001) with mean daytime sleep latency compared to AHI (ρ = -.402, P < 0.001) and ODI (ρ = -.393, P < .001). Based on general regression model, desaturation severity and male sex were the most significant factors predicting daytime sleep latency. Severity of sleep-related breathing cessations and desaturations is a stronger contributor to daytime sleepiness than AHI or ODI and therefore should be included in the diagnostics and severity assessment of OSA. Kainulainen S, Töyräs J, Oksenberg A, Korkalainen H, Sefa S, Kulkas A, Leppänen T. Severity of desaturations reflects OSA-related daytime sleepiness better than AHI. J Clin Sleep Med. 2019;15(8):1135-1142.

The hypoxic burden: a novel sleep apnoea severity metric and a predictor of cardiovascular mortality-Reply to 'The hypoxic burden: also known as the desaturation severity parameter'.

The hypoxic burden: a novel sleep apnoea severity metric and a predictor of cardiovascular mortality-Reply to 'The hypoxic burden: also known as the desaturation severity parameter'.