RemLogic plug-in enables clinical application of apnea-hypopnea index adjusted for severity of individual obstruction events

Adjusting the apnea-hypopnea index in children with a low percentage of REM sleep and its potential impact on OSA diagnosis and severity

STUDY OBJECTIVES

A decrease in rapid eye movement (REM) time during polysomnography in patients with obstructive sleep apnea (OSA) can result in underestimation of apnea-hypopnea index (AHI). We propose adjusting AHI to normalized REM% in individuals with REM% ≤ 15% to avoid underdiagnosis of OSA.

METHODS

All children who completed diagnostic polysomnography from 2016-2023 with REM% of ≤ 15% of total sleep time were selected for adjustment. AHI adjustment was done by multiplying AHI by a normalization factor (20%)/REM%. Changes in OSA diagnosis and severity were evaluated before vs after adjustment. Intraclass comparison and Bland-Altman plots were used to evaluate agreement level of adjusted AHI vs nonadjusted AHI with REM AHI as the reference. P value < .05 was significant.

RESULTS

Of 389 children reviewed, only 79 (20%) children had low REM% of ≤ 15%. Median (range) age was 12.8 (0.9-18) years with male/female ratio 2.3/1. Mean (standard deviation) sleep efficiency was 64.7% (12.3). Mean (standard deviation) REM% was 10.5% (3.4). Median AHI (range) before AHI adjustment was 1.7 (0-44) events/h vs 4.1 (0-74.4) events/h after AHI adjustment (P < .001). Adjusted AHI had better agreement with REM-AHI (intraclass correlation = .691; 95% confidence interval: 0.58, 0.80) than nonadjusted AHI (intraclass correlation = .485; 95% confidence interval: 0.39, 0.58). AHI adjustment changed diagnosis from normal to mild OSA in 12 (15%) patients, from mild to moderate OSA in 7 (9%) patients, and from moderate to severe OSA in 9 (11%) patients (P = .044).

CONCLUSIONS

Adjusting AHI in patients with low REM% to a normalized REM% can help avoid underdiagnosis of OSA and/or underestimation of its severity.

CITATION

Alnaimi A, Toma H, Abushahin A, Belavendra A, Abu-Hasan M. Adjusting the apnea-hypopnea index in children with a low percentage of REM sleep and its potential impact on OSA diagnosis and severity. J Clin Sleep Med. 2025;21(5):783-788.

Obstructive sleep apnea‐related intermittent hypoxaemia is associated with impaired vigilance

Obstructive sleep apnea (OSA)-related intermittent hypoxaemia is a potential risk factor for different OSA comorbidities, for example cardiovascular disease. However, conflicting results are found as to whether intermittent hypoxaemia is associated with impaired vigilance. Therefore, we aimed to investigate how desaturation characteristics differ between the non-impaired vigilance and impaired vigilance patient groups formed based on psychomotor vigilance task (PVT) performance and compared with traditional OSA severity parameters. The study population comprised 863 patients with suspected OSA who underwent a PVT test before polysomnography. The conventional OSA parameters, for example, the apnea-hypopnea index, oxygen desaturation index, and arousal index were computed. Furthermore, the median desaturation area, fall area, recovery area, and desaturation depth were computed with the pre-event baseline reference and with reference to the 100% oxygen saturation level. Patients were grouped into best- and worst-performing quartiles based on the number of lapses in PVT (Q1: PVT lapses <5 and Q4: PVT lapses >36). The association between parameters and impaired vigilance was evaluated by cumulative distribution functions (CDFs) and binomial logistic regression. Based on the CDFs, patients in Q4 had larger desaturation areas, recovery areas, and deeper desaturations when these were referenced to 100% saturation compared with Q1. The odds ratio (OR) of the median desaturation area (OR = 1.56), recovery area (OR = 1.71), and depth (OR = 1.65) were significantly elevated in Q4 in regression models. However, conventional OSA parameters were not significantly associated with impaired vigilance (ORs: 0.79-1.09). Considering desaturation parameters with a 100% SpO₂ reference in the diagnosis of OSA could provide additional information on the severity of OSA and related daytime vigilance impairment.

Duration of respiratory events in obstructive sleep apnea: In search of paradoxical results

Research related to the duration of respiratory events in obstructive sleep apnea (OSA) has been scarce, perhaps due to the dominant role played by the apnea-hypopnea index (AHI) in the diagnosis and severity estimation of OSA. Lately, however, researchers and clinicians have started to acknowledge the importance of this overlooked parameter. Intuitively, 40-s-long apneas have more harmful physiological and health consequences than 10-s-long apneas. But is this the case? Here, we review the research-based evidence showing physiological, hemodynamic, clinical, sleep quality, and health consequences of long vs. short respiratory events. Most of the reviewed studies support the idea that longer respiratory events have more severe physiological and clinical consequences than shorter events, most probably due to the higher hypoxic burden associated with longer respiratory events. However, a few but highly qualified studies provide clear evidence that short respiratory events have also a deleterious effect on sleep and the physiological and clinical aspects of OSA. The somewhat paradoxical findings that short respiratory events are also associated with a high risk of all-cause mortality is a serious concern. From these results, it is therefore evident that the duration of respiratory events should be quantified when diagnosing and assessing the severity of OSA.

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

STUDY OBJECTIVES

The aim was to investigate how the severity of apneas, hypopneas, and related desaturations is associated with obstructive sleep apnea (OSA)-related daytime sleepiness.

METHODS

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).

RESULTS

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 (t_90%) (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.

CONCLUSIONS

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.

CITATION

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.

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 (OR_range 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 (OR_range 1.26–1.52, p<0.05) associated with prolonged median reaction time. Female sex (OR_range 2.21–6.02, p<0.01), Epworth Sleepiness Scale score (OR_range 1.05–1.07, p<0.01) and older age (OR_range 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.

Parameters considering characteristic properties of desaturations have a significant association with impaired vigilance, highlighting the importance of developing methods beyond the AHI for a more detailed assessment of OSA severityhttp://bit.ly/2veqxD9

Polysomnographic characteristics of severe obstructive sleep apnea vary significantly between hypertensive and normotensive patients of both genders

PURPOSE

Hypertension is a common finding in patients with obstructive sleep apnea (OSA), but it has remained unclear whether or not the amount of disturbed breathing and characteristics of individual respiratory events differ between hypertensive and normotensive patients with severe OSA.

METHODS

Full polysomnographic recordings of 323 men and 89 women with severe OSA were analyzed. Differences in the duration of individual respiratory events, total apnea and hypopnea times, and the percentage of disturbed breathing from total sleep time (AHT%) were compared between normotensive and hypertensive patients separately by genders. Furthermore, differences in the respiratory event characteristics were assessed between three AHT% groups (AHT% ≤ 30%, 30% < AHT% ≤ 45%, and AHT% > 45%).

RESULTS

Hypertensive women had lower percentage apnea time (15.2% vs. 18.2%, p = 0.003) and AHT% (33.5% vs. 36.5%, p = 0.021) when compared with normotensive women. However, these differences were not observed between hypertensive and normotensive men. Percentage hypopnea time was higher in hypertensive men (13.5% vs. 11.2%, p = 0.043) but not in women (15.2% vs. 12.2%, p = 0.130) compared with their normotensive counterparts. The variation in AHI explained 60.5% (ρ = 0.778) and 65.0% (ρ = 0.806) of the variation in AHT% in normotensive and hypertensive patients, respectively. However, when AHT% increased, the capability of AHI to explain the variation in AHT% declined.

CONCLUSIONS

There is a major inter- and intra-gender variation in percentage apnea and hypopnea times between hypertensive and normotensive patients with severe OSA. OSA is an important risk factor for hypertension and thus, early detection and phenotyping of OSA would allow timely treatment of patients with the highest risk of hypertension.

Bayesian Network Model to Evaluate the Effectiveness of Continuous Positive Airway Pressure Treatment of Sleep Apnea

OBJECTIVES

The association between obstructive sleep apnea (OSA) and mortality or serious cardiovascular events over a long period of time is not clearly understood. The aim of this observational study was to estimate the clinical effectiveness of continuous positive airway pressure (CPAP) treatment on an outcome variable combining mortality, acute myocardial infarction (AMI), and cerebrovascular insult (CVI) during a follow-up period of 15.5 years (186 ± 58 months).

METHODS

The data set consisted of 978 patients with an apnea-hypopnea index (AHI) ≥5.0. One-third had used CPAP treatment. For the first time, a data-driven causal Bayesian network (DDBN) and a hypothesis-driven causal Bayesian network (HDBN) were used to investigate the effectiveness of CPAP.

RESULTS

In the DDBN, coronary heart disease (CHD), congestive heart failure (CHF), and diuretic use were directly associated with the outcome variable. Sleep apnea parameters and CPAP treatment had no direct association with the outcome variable. In the HDBN, CPAP treatment showed an average improvement of 5.3 percentage points in the outcome. The greatest improvement was seen in patients aged ≤55 years. The effect of CPAP treatment was weaker in older patients (>55 years) and in patients with CHD. In CHF patients, CPAP treatment was associated with an increased risk of mortality, AMI, or CVI.

CONCLUSIONS

The effectiveness of CPAP is modest in younger patients. Long-term effectiveness is limited in older patients and in patients with heart disease (CHD or CHF).