Evaluating the clinical value of the hypoxia burden index in patients with obstructive sleep apnea

Associations of baseline obstructive sleep apnea and sleep macroarchitecture with cognitive function after 8 years in middle-aged and older men from a community-based cohort study

Previous prospective studies examining associations of obstructive sleep apnea and sleep macroarchitecture with future cognitive function recruited older participants, many demonstrating baseline cognitive impairment. This study examined obstructive sleep apnea and sleep macroarchitecture predictors of visual attention, processing speed, and executive function after 8 years among younger community-dwelling men. Florey Adelaide Male Ageing Study participants (n = 477) underwent home-based polysomnography, with 157 completing Trail-Making Tests A and B and the Mini-Mental State Examination. Associations of obstructive sleep apnea (apnea-hypopnea index, oxygen desaturation index, and hypoxic burden index) and sleep macroarchitecture (sleep stage percentages and total sleep time) parameters with future cognitive function were examined using regression models adjusted for baseline demographic, biomedical, and behavioural factors, and cognitive task performance. The mean (standard deviation) age of the men at baseline was 58.9 (8.9) years, with severe obstructive sleep apnea (apnea-hypopnea index ≥30 events/h) in 9.6%. The median (interquartile range) follow-up was 8.3 (7.9-8.6) years. A minority of men (14.6%) were cognitively impaired at baseline (Mini-Mental State Examination score <28/30). A higher percentage of light sleep was associated with better Trail-Making Test A performance (B = -0.04, 95% confidence interval [CI] -0.06, -0.01; p = 0.003), whereas higher mean oxygen saturation was associated with worse performance (B = 0.11, 95% CI 0.02, 0.19; p = 0.012). While obstructive sleep apnea and sleep macroarchitecture might predict cognitive decline, future studies should consider arousal events and non-routine hypoxaemia measures, which may show associations with cognitive decline.

Obstructive sleep apnea diagnosis and beyond using portable monitors

Obstructive sleep apnea (OSA) is a chronic sleep and breathing disorder with significant health complications, including cardiovascular disease and neurocognitive impairments. To ensure timely treatment, there is a need for a portable, accurate and rapid method of diagnosing OSA. This review examines the use of various physiological signals used in the detection of respiratory events and evaluates their effectiveness in portable monitors (PM) relative to gold standard polysomnography. The primary objective is to explore the relationship between these physiological parameters and OSA, their application in calculating the apnea hypopnea index (AHI), the standard metric for OSA diagnosis, and the derivation of non-AHI metrics that offer additional diagnostic value. It is found that increasing the number of parameters in PMs does not necessarily improve OSA detection. Several factors can cause performance variations among different PMs, even if they extract similar signals. The review also highlights the potential of PMs to be used beyond OSA diagnosis. These devices possess parameters that can be utilized to obtain endotypic and other non-AHI metrics, enabling improved characterization of the disorder and personalized treatment strategies. Advancements in PM technology, coupled with thorough evaluation and validation of these devices, have the potential to revolutionize OSA diagnosis, personalized treatment, and ultimately improve health outcomes for patients with OSA. By identifying the key factors influencing performance and exploring the application of PMs beyond OSA diagnosis, this review aims to contribute to the ongoing development and utilization of portable, efficient, and effective diagnostic tools for OSA.

Association between hypoxic burden and common cardiometabolic diseases in patients with severe obstructive sleep apnea

PURPOSE

To determine the possible associations between total sleep time spent with arterial oxygen saturation < 90% (T90) and comorbid cardiometabolic diseases (CMDs) in patients with severe obstructive sleep apnea (OSA).

METHODS

A retrospective review of the chart was conducted in patients with severe OSA diagnosed by in-lab polysomnography (PSG) between January 2018 and December 2019 at Siriraj Hospital. The patients were divided into two groups: hypoxic (T90 ≥ 10%) and nonhypoxic (T90 < 10%). The association between common CMDs including hypertension (HT), type 2 diabetes mellitus (T2DM), and impaired fasting glucose (IFG) was investigated and compared between the two groups.

RESULTS

Data were collected from 450 patients with severe OSA, 289 males/161 females with a mean age of 53.5 ± 14.2 years and an apnea-hypopnea index (AHI) of 49.6 events/h. Among these, 114 patients (25.3%) were defined as the hypoxic group (T90 ≥ 10%). When compared between the hypoxic and nonhypoxic groups, the patients in the hypoxic group were significantly younger and more obese, and had a higher proportion of male patients. The majority of patients (80%) had at least one CMD; however, the most common comorbidities significantly associated with hypoxic OSA (T90 ≥ 10%) were HT and IFG.

CONCLUSION

Hypoxic burden is significantly associated with an increased prevalence of HT and IFG in patients with severe OSA. T90 may be potentially useful for predicting CMDs in these patients. However, prospective studies are still required.

Characteristics and feasibility of ambulatory respiratory assessment of paediatric neuromuscular disease: an observational retrospective study

PURPOSE

To investigate the characteristics of respiratory involvement in Chinese paediatric neuromuscular disease (NMD) at early stage and to explore convenient monitoring methods.

MATERIALS AND METHODS

Children with NMD (age < 18) diagnosed at a multidisciplinary joint NMD clinic at Peking University First Hospital from January 2016 to April 2021 were included. Overnight polysomnography (PSG) and pulmonary function test (PFT) data were analysed, and the characteristics of four groups: congenital muscular dystrophy (CMD), congenital myopathy, spinal muscular atrophy, and Duchenne muscular dystrophy (DMD) were compared.

RESULTS

A total of 83 children with NMD were referred for respiratory assessment, of who 80 children underwent PSG; 41 performed spirometry and 38, both. The duration of pulse oxygen saturation (SpO2) <90% over apnoea and hypopnoea index (AHI) was lowest in DMD and significantly different from CMD (p = 0.033). AHI was positively correlated with the oxygen desaturation index (ODI) (r = 0.929, p = 0.000). The peak expiratory flow (PEF) were positively correlated with forced vital capacity (FVC), both as actual values and percent pred, respectively (r = 0.820, 0.719, p = 0.000). ROC derived sensitivity and specificity of prediction of AHI > 15/h or duration of SpO2<90% ≥ 60 min from FVC <51% pred was 75.8% and 85.7%, respectively.

CONCLUSIONS

AHI and hypoxia burden were independent factors in children with NMD in PSG and attention needed to be paid in both. FVC might be a daytime predictor for significant sleep-disordered breathing or hypoxia. Nocturnal consecutive oximetry with diurnal peak flow measurement may be convenient and effective for home monitoring at early stage of respiratory involvement.

Proposal of a diagnostic algorithm based on the use of pulse oximetry in obstructive sleep apnea

PURPOSE

The aims of this study were to assess the cut-off values for oxygen desaturation index ≥ 3% (ODI3) to confirm obstructive sleep apnea (OSA) in subjects undergoing polysomnography (PSG) and home-based respiratory polygraphy (RP), and to propose an algorithm based on pulse oximetry (PO) for initial management of patients with suspected OSA.

METHODS

This was an observational, cross-sectional, retrospective study. ODI3 was used to classify subjects as healthy (no OSA = AHI < 5 or < 15 events/h) or unhealthy (OSA = AHI ≥ 5 or ≥ 15 events/h). On the PSG or experimental group (Exp-G), we determined ODI3 cut-off values with 100% specificity (Sp) for both OSA definitions. ODI3 values without false positives in the Exp-G were applied to a validation group (Val-G) to assess their performance. A strategy based on PO was proposed in patients with suspected OSA.

RESULTS

In Exp-G (PSG) 1141 patients and in Val-G (RP) 1141 patients were included. In Exp-G, ODI3 > 12 (OSA = AHI ≥ 5) had a sensitivity of 69.5% (CI95% 66.1-72.7) and Sp of 100% (CI95% 99-100), while an ODI3 ≥ 26 had a 53.8% sensitivity (CI95% 49.3-58.2) and Sp of 100% (CI95% 99.4-100) for AHI ≥ 15. A high pretest probability for OSA by Berlin questionaire (≥ 2 categories) had a lower diagnostic performance than by STOP-BANG questionnaire ≥ 5 points (AHI ≥ 5: 0.856 vs. 0.899, p < 0.001; AHI ≥ 15: 0.783 vs. 0.807, p 0.026).

CONCLUSION

We propose the initial use of PO at home in cases of moderate-to-high pretest probability of OSA. This algorithm considers PO as well as RP and PSG for more challenging cases or in case of doubt.

Sleep apnea is associated with the increase of certain genera of Ruminococcaceae and Lachnospiraceae in the gut microbiome of hypertensive patients

BACKGROUND

Obstructive sleep apnea (OSA) and hypertension are interrelated diseases linked to gut dysbiosis. This study aimed to investigate the effect of OSA on the gut microbiome in the context of hypertension and vice versa.

RESEARCH DESIGN AND METHODS

Of 211 consecutively screened patients, 52 completed polysomnography study, medical history questionnaires, and fecal sample collection. 16S rRNA gene sequencing was performed on fecal samples, and diversity, richness, and microbial taxa were analyzed using bioinformatics.

RESULTS

Alpha diversity showed slightly decreased diversity in OSA and hypertension groups without significant difference, and the hypoxia burden index (HBI) showed a weak positive correlation with Chao1 index (r = 0.342, p < 0.05) in OSA patients. Firmicutes-to-Bacteroidetes ratio was higher in patients with than without OSA. In hypertensive patients, those with OSA had higher Ruminococcus_1, Lachnoclostridium, Lachnospira, [Ruminococcus]_torques_group, and unidentified Lachnospiraceae levels than those without OSA. Conversely, in OSA patients, hypertensive patients had lower Faecalibacterium and Lachnospiraceae_NK4A136_group levels.

CONCLUSION

The present study suggests a possible compensatory mechanism for gut microbiome changes in sleep apnea pathophysiology. The positive correlation between HBI and alpha diversity, and increase in certain genera of Ruminococcaceae and Lachnospiraceae in OSA patients may represent an adaptive response to hypoxia.

Association between apnea-hypopnea index and coronary artery calcification: a systematic review and meta-analysis

BACKGROUND

The present study aimed to evaluate the association between presence and severity of obstructive sleep apnoea (OSA) and the presence of subclinical coronary artery disease (CAD) as assessed by coronary calcium score.

METHODS

Medline, Cochrane, and Google Scholar databases were searched. The presence of coronary artery calcification (CAC) and CAC score were assessed.

RESULTS

Irrespective of the cut-off value of apnoea-hypopnea index (AHI) (5 or 15 events/h), patients in the OSA group had higher rate of CAC presence and mean CAC score than those in the control group. Subgroup analyses of patients monitored with home sleep apnoea testing (HSAT) or in-hospital/laboratory polysomnography showed that the OSA group had higher rate of CAC presence and mean CAC score than the control group, except in the comparison of mean CAC score between AHI ≥5 vs. <5 events/h for patients using HSAT, which was not significant. Pair-wise comparison showed that CAC score may increase with increased OSA severity.

CONCLUSIONS

In participants without symptomatic coronary disease, the presence of OSA was associated with the presence and extent of CAC. However, potential confounders such as age, gender, and BMI and the diversity of CAC scores may affect the association.

Nocturnal oximetry in the diagnosis of obstructive sleep apnea syndrome in potentially hypoxic patients due to neuromuscular diseases

INTRODUCTION

Polysomnography is the recommended method for the diagnosis of obstructive sleep apnea (OSA); however, it is expensive, uncomfortable, and inaccessible. Alternative diagnostic methods are necessary, and Nocturnal Oximetry (NO) has proven to be reliable. Nevertheless, there have been doubts about its accuracy in patients with a history of hypoxia. Hence, the objective of this study was to evaluate the performance of NO in patients with neuromuscular diseases (NMD).

METHOD

This was a cross-sectional study in patients with NMD suspected of having OSA. We performed a statistical analysis using Spearman's correlation coefficients (SCCs). We used the value of the area under the ROC curve (AUCROC), just as we calculated the sensitivities (Sens) and specificities (Spec) for the chosen variables.

RESULTS

The sample comprised 41 patients; 51.2% with muscular dystrophies and 48.8% with motor neuron diseases, with a predominance of men (63.4%). Median age was 42 (19.7-55) years, body mass index (BMI) was 27.9 (23.8-32) kg/m2, forced vital capacity was 67% (54%-76.5%), and maximum inspiratory pressure was-60 cmH2O (-87.5 to -50). The prevalence of OSA was 75.7%. We analyzed and selected the best four oximetric variables with the following performance in identifying the apnea/hypopnea index >5/h, ODI3/2, cutoff>5/h, AUCROC 0.919, Sens 82.3%, Spec 91.7%; ODI3/5, cutoff>11.2/h, AUCROC 0.904, Sens 82.3%, Spec 87.5%; ODI4/5, cutoff>6.02, AUCROC 0.839, Sens 70.6%, Spec 91.6%, and ODI5/5, cutoff>0.87/h, AUCROC 0.870, Sens 94.1%, and Spec 70.8%.

CONCLUSION

NO can be used as a diagnostic tool for OSA, even in patients with neuromuscular diseases and potentially hypoxic diseases.

Nocturnal heart rate variability in obstructive sleep apnoea: a cross-sectional analysis of the Sleep Heart Health Study

Background

Obstructive sleep apnoea (OSA) results in sympathetic overdrive. Increased nocturnal heart rate variability (HRV) is a surrogate marker of autonomic disturbance. The aim was to study the association of the apnoea-hypopnea index (AHI), nocturnal hypoxaemia, and sleep fragmentation with nocturnal HRV to address the pathophysiological mechanisms underlying autonomic disturbance in OSA.

Methods

Participants of the Sleep Hearth Health Study with available data on nocturnal HRV and an AHI ≥10/h have been included in this cross-sectional analysis. The main outcome of interest was the association of sleep fragmentation, nocturnal hypoxaemia, and the AHI with nocturnal HRV. Multivariate regression modelling with the mean of the standard deviations of normal-sinus-to-normal-sinus-interbeat intervals in all 5-minute segments (SDNNIDX) and with low to high frequency power-ratio (LF/HF) as dependent variables controlling for prespecified confounders (age, sex, cups of coffee, beta blocker, nocturnal heart rate) was used to assess the contribution of the arousal index, total sleep time with an oxygen saturation <90% (TST90) and the AHI not due to arousals to HRV. The significance level was set at P<0.01.

Results

In 258 patients with OSA (mean ± SD age 62±10 years, BMI 29±4 kg/m², median (IQR) AHI 18.6/h (14.0-25.6), the arousal index (coef =0.42, P=0.002) was independently positively associated with SDNNIDX also after having controlled for potential confounders, whereas the AHI (coef =0.22, P=0.030) and TST90 (coef =0.36, P=0.054) were not. The arousal index-but not TST and AHI-was also independently associated with LF/HF.

Conclusions

In OSA, pronounced sleep fragmentation is associated with higher nocturnal HRV and a sympatho-vagal imbalance with sympathetic dominance. OSA severity and nocturnal hypoxaemia did not independently predict nocturnal HRV.

Intermittent hypoxia in preterm infants: Measurement using the desaturation index

OBJECTIVE

The aims of this study were to: (i) Determine in preterm infants at neonatal discharge the prevalence of intermittent hypoxia (IH), as measured by the oxygen desaturation index (DSI) recorded by pulse oximetry and (ii) Determine the change in values for very preterm infants at 1-month post discharge.

METHODS

Preterm infants were recruited from the Wellington regional neonatal intensive care unit (NICU) and 24-h pulse oximetry recordings performed immediately before discharge. Infants born <32 weeks gestational age (GA) had repeat oximetry 1-month post discharge. Oxygenation measures included the 3% and 4% desaturation (DSI 3%, DSI 4%) indices.

RESULTS

At discharge from the neonatal unit the median and interquartile range (IQR) for DSI 4% was 51 (31-74) events per hour with normal mean SpO₂ (median of 97.9% [97.2-98.8 IQR]). Episodes of IH 1 month post discharge decreased with improvements of between 42% and 57% seen for the three DSI measures. Infants <32 weeks GA had higher median DSI 3 and 4% values at discharge but differences when compared with late preterm infants were not significant.

CONCLUSIONS

Preterm infants have frequent episodes of IH as measured by the 3% and 4% DSI when deemed otherwise ready for discharge home. Further research in a larger cohort of very preterm infants and also in term infants is needed to determine the significance of this finding.