Optimal positive airway pressure requirement and polysomnography indices of obstructive sleep apnea severity in the Saudi population.

CONTEXT: Positive airway pressure (PAP) is the first-line therapy for obstructive sleep apnea (OSA). Overnight PAP titration for determining optimal PAP requirements is expensive and often inconvenient. Prediction of optimal PAP requirements from diagnostic polysomnography via mathematical equations is possible but variable across populations. AIMS: We aimed to (1) determine the optimal PAP requirement, (2) determine differences in optimal PAP requirements across OSA severity groups, (3) determine the relationship between optimal PAP requirement and diagnostic polysomnography measurements of OSA severity, and (4) develop a pilot equation to predict the optimal PAP requirement from diagnostic polysomnography in a sample from the Saudi population. METHODS: We analyzed records pertaining to adult OSA patients (n = 215; 63% of males) who underwent standardized diagnostic and titration polysomnography in our sleep laboratory between 2015 and 2019. Demographic, anthropometric, and clinical information were also collected for the analysis. Inferential statistics were performed for comparisons between diagnostic and titration studies and between OSA severity groups. Regression analyses were also performed to determine the potential predictors of optimal PAP requirements. Data were presented as the mean (± standard deviation) or median (25th-75th quartiles) according to normality. RESULTS: The median optimal PAP requirement was 13 (9-17) cmH2O. The optimal PAP requirement was significantly greater for male versus female participants (14 [10-17] vs. 12 [8-16] cmH2O) and for participants with severe OSA (16 [12-20] cmH2O, n = 119) versus those with moderate (11 [8-14] cmH2O, n = 63) or mild (9 [7-12] cmH2O, n = 33) OSA. When combined, nadir oxygen saturation, oxygen desaturation index, and arousal index could be used to predict the optimal PAP requirement (R 2= 0.39, F = 34.0, P < 0.001). CONCLUSIONS: The optimal PAP requirement in the Saudi population is relatively high and directly correlated with OSA severity. Diagnostic polysomnography measurements of OSA severity predicted the optimal PAP requirement in this sample. Prospective validation is warranted.

Sleep-disordered breathing in patients with stroke-induced dysphagia.

This study examined the nature and characteristics of sleep-disordered breathing, including obstructive sleep apnea and central sleep apnea, in patients with post-stroke dysphagia, to determine the demographic, anthropometric and clinical variables that were associated with sleep-disordered breathing. Thirty-nine patients diagnosed with acute stroke (28 males and 11 females with a mean age of 72.3 ± 10.0 years) underwent overnight polysomnography (within 3.9 ± 1.6 days after admission). Sleep-disordered breathing was described by the apnea-hypopnea index and its obstructive and central components by the obstructive apnea-hypopnea index and central apnea-hypopnea index, respectively. Severity of dysphagia was assessed using the Mann Assessment of Swallowing Ability score. Severity of stroke and functional dependence were assessed by the National Institute of Health Stroke Scale and the modified Barthel index, respectively. Most of the cohort (87%) had moderate-to-severe dysphagia (Mann Assessment of Swallowing Ability of 143.2 ± 19.9). Sleep-disordered breathing (apnea-hypopnea index ≥ 5 events/hr) was present in 38 participants (97%) with a mean apnea-hypopnea index of 37.5 ± 24.4 events/hr. Sleep-disordered breathing was predominantly obstructive in nature, with a mean obstructive apnea-hypopnea index and central apnea-hypopnea index of 19.6 ± 15.7 and 11.4 ± 17.6 events/hr, respectively. Multivariate linear regression analyses showed that the apnea-hypopnea index was associated with sex (p = .0001), body mass index (p = .029) and the modified Barthel index (p = .006); the obstructive apnea-hypopnea index was associated with the Mann Assessment of Swallowing Ability (p = .006), sex (p = .004) and body mass index (p = .015) and had a nonlinear relationship with the modified Barthel index (p = .019); and the central apnea-hypopnea index was associated with sex (p = .027) and the modified Barthel index (p = .019). The present study showed that dysphagia severity was associated with obstructive sleep apnea severity and this association was independent of sex, modified Barthel index and body mass index. However, stroke-induced dysphagia was not associated with central sleep apnea or overall sleep-disordered breathing.

Dose-dependent effects of mandibular advancement on optimal positive airway pressure requirements in obstructive sleep apnoea.

BACKGROUND: Implementation of mandibular advancement splint (MAS) therapy as first-line treatment for obstructive sleep apnoea (OSA) is hindered by inter-individual variability of treatment outcomes and lack of robust patient selection methods. Optimal continuous positive airway pressure (CPAP) requirement provides an estimate of airway collapsibility severity, and high CPAP requirements predict MAS therapy failure in retrospective studies. Thus, understanding the effects of mandibular advancement on optimal CPAP requirements may enhance optimisation of patient selection for MAS therapy. OBJECTIVE: This study aims to determine dose-dependent effects of mandibular advancement on optimal CPAP requirements in OSA. METHODS: Prior to MAS therapy initiation, participants with OSA (apnoea-hypopnea index (AHI) > 10 events/h) underwent a research polysomnogram in which a remotely controlled mandibular positioner (RCMP) was used to determine dose-response effects of varying mandibular advancement positions (0% 'habitual bite' and 25, 50, 75 and 100% of maximum mandibular advancement, in random order) on optimal CPAP requirements. A separate polysomnography determined treatment outcome. Data are presented as mean ± SD or median (1st-3rd quartiles). RESULTS: Seventeen participants (age = 47 ± 9 years, body mass index = 26 kg/m2 (23-27), apnoea-hypopnea index = 18 events/h (14-44) and minimal oxygen saturation = 84 ± 7%) were studied. Optimal CPAP requirements were reduced with mandibular advancement in a dose-dependent manner (8.9 ± 2.4 vs. 7.9 ± 2.8, 6.4 ± 1.8, 5.7 ± 1.9 and 4.9 ± 1.8 cmH2O; respectively, p < 0.0001). Compared with non-responders, responders to MAS therapy had lower AHI, lower arousal index and greater MinSaO2 at baseline. Optimal CPAP requirements at 0% mandibular advancement (or other positions) were not different between groups. CONCLUSIONS: Increasing mandibular advancement lowers optimal CPAP requirements in a dose-dependent manner. This supports prior work indicating a beneficial effect of MAS on upper airway collapsibility.

Polysomnographic Endotyping to Select Patients with Obstructive Sleep Apnea for Oral Appliances.

Rationale: Oral appliance therapy is efficacious in many patients with obstructive sleep apnea (OSA), but prediction of treatment outcome is challenging. Small, detailed physiological studies have identified key OSA endotypic traits (pharyngeal collapsibility and loop gain) as determinants of greater oral appliance efficacy.Objectives: We used a clinically applicable method to estimate OSA traits from routine polysomnography and identify an endotype-based subgroup of patients expected to show superior efficacy.Methods: In 93 patients (baseline apnea-hypopnea index [AHI], ≥20 events/h), we examined whether polysomnography-estimated OSA traits (pharyngeal: collapsibility and muscle compensation; nonpharyngeal: loop gain, arousal threshold, and ventilatory response to arousal) were associated with oral appliance efficacy (percentage reduction in AHI from baseline) and could predict responses to treatment. Multivariable regression (with interactions) defined endotype-based subgroups of "predicted" responders and nonresponders (based on 50% reduction in AHI). Treatment efficacy was compared between the predicted subgroups (with cross-validation).Results: Greater oral appliance efficacy was associated with favorable nonpharyngeal traits (lower loop gain, higher arousal threshold, and lower response to arousal), moderate (nonmild, nonsevere) pharyngeal collapsibility, and weaker muscle compensation (overall R2 = 0.30; adjusted R2 = 0.19; P = 0.003). Predicted responders (n = 54), compared with predicted nonresponders (n = 39), exhibited a greater reduction in AHI from baseline (mean [95% confidence interval], 73% [66-79] vs. 51% [38-61]; P < 0.0001) and a lower treatment AHI (8 [6-11] vs. 16 [12-20] events/h; P = 0.002). Differences persisted after adjusting for clinical covariates (including baseline AHI, body mass index, and neck circumference).Conclusions: Quantifying OSA traits using clinical polysomnography can identify an endotype-based subgroup of patients that is highly responsive to oral appliance therapy. Prospective validation is warranted.

Dose-dependent effects of mandibular advancement on upper airway collapsibility and muscle function in obstructive sleep apnea.

STUDY OBJECTIVES: Mandibular advancement splints (MAS) are the leading treatment alternative to continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA). However, not all patients experience clinical benefit and treatment prediction remains challenging. Understanding the effects of mandibular advancement on pharyngeal collapsibility and muscle function may provide valuable information on the mechanisms of MAS, and thereby help to develop novel approaches for patient selection. Thus, we aimed to determine dose-dependent effects of mandibular advancement on pharyngeal collapsibility and muscle function concurrently in OSA patients undergoing MAS therapy. METHODS: Twelve (11 male) MAS-naïve patients underwent a detailed physiology sleep study (polysomnography) to quantify pharyngeal collapsibility (PCRIT), pharyngeal muscle responsiveness to negative pharyngeal pressure (via genioglossus intramuscular electromyography and an epiglottic pressure sensor) and effectiveness to restore airflow and minute ventilation (Vi) after 1-minute transient CPAP reductions (induced airflow-limitation) at three mandibular advancement positions: 0% (habitual bite), 50% and 100% of the maximum comfortable mandibular advancement. Standard clinical polysomnography after MAS therapy optimization was performed to determine treatment outcome. RESULTS: Overall, participants were obese with severe OSA (mean ± SD: BMI = 31 ± 4 kg/m2, apnea-hypopnea index [AHI] = 33 ± 14 events/hour). PCRIT decreased with mandibular advancement in a dose-dependent manner (1.8 ± 3.9 vs. -0.9 ± 2.9 vs. -4.0 ± 3.6 cmH2O; p < 0.001). There was no systematic change in genioglossus muscle responsiveness (p = 0.09) or effectiveness to restore peak airflow (p = 0.4) or Vi (p = 0.7) with mandibular advancement. CONCLUSIONS: Mandibular advancement reduces pharyngeal collapsibility in a dose-dependent manner without systematically changing genioglossus muscle function in a predominantly obese and severe OSA population. This indicates that the primary mode of action of MAS therapy is via improvement in passive pharyngeal anatomy.

Mandibular Advancement Splints.

Although mandibular advancement splints (MAS) are not as efficacious as continuous positive airway pressure (CPAP) in reducing obstructive respiratory events, patient adherence and preference are greater than CPAP. Additionally, the effectiveness of both treatments on general health outcomes, cognitive function, and quality of life appears to be equivalent. The main barrier for the implementation of MAS treatment in clinical practice is the interindividual variability in response to MAS treatment. Several prediction tools have been proposed to enhance patient selection for MAS treatment. Phenotyping obstructive sleep apnea patients may reveal patient characteristics that enable the prediction of response to MAS treatment.