Effect of Sleeping Position on Upper Airway Patency in Obstructive Sleep Apnea Is Determined by the Pharyngeal Structure Causing Collapse

Abstract

Objectives:In some patients, obstructive sleep apnea (OSA) can be resolved with improvement in pharyngeal patency by sleeping lateral rather than supine, possibly as gravitational effects on the tongue are relieved. Here we tested the hypothesis that the improvement in pharyngeal patency depends on the anatomical structure causing collapse, with patients with tongue-related obstruction and epiglottic collapse exhibiting preferential improvements. Methods: Twenty-four OSA patients underwent upper airway endoscopy during natural sleep to determine the pharyngeal structure associated with obstruction, with simultaneous recordings of airflow and pharyngeal pressure. Patients were grouped into three categories based on supine endoscopy: Tongue-related obstruction (posteriorly located tongue, N = 10), non-tongue related obstruction (collapse due to the palate or lateral walls, N = 8), and epiglottic collapse (N = 6). Improvement in pharyngeal obstruction was quantified using the change in peak inspiratory airflow and minute ventilation lateral versus supine. Results: Contrary to our hypothesis, patients with tongue-related obstruction showed no improvement in airflow, and the tongue remained posteriorly located while lateral. Patients without tongue involvement showed modest improvement in airflow (peak flow increased 0.07 L/s and ventilation increased 1.5 L/min). Epiglottic collapse was virtually abolished with lateral positioning and ventilation increased by 45% compared to supine position. Conclusions: Improvement in pharyngeal patency with sleeping position is structure specific, with profound improvements seen in patients with epiglottic collapse, modest effects in those without tongue involvement and-unexpectedly-no effect in those with tongue-related obstruction. Our data refute the notion that the tongue falls back into the airway during sleep via gravitational influences.

Predicting epiglottic collapse in patients with obstructive sleep apnoea

“…The results of the present study show that epiglottic collapse is associated with distinct flow shapes that can be quantified objectively. As described in our recent study, a cardinal feature of epiglottic collapse is the fact that it is intermittent[17]. In addition to its intermittency, this study shows that the most important feature distinguishing epiglottic collapse from other types of airway collapse is the presence of discontinuities in the flow (quantified by the discontinuity and jaggedness indices).…”

“…The method developed in this study can be used to test whether epiglottic collapse, assessed using this approach, predicts responses to therapy, including failure of oral appliances[9], surgery[33], increased occurrence of collapse on CPAP[10, 11, 32], and effectiveness of positional therapy[17, 32]. In addition, its utility as a screening tool for epiglottis-related surgery can be tested.…”

“…limited memory on the local computer). In addition, breaths were excluded from the analysis if: 1) they occurred during wakefulness, REM sleep, or arousals, 2) they occurred during sleep in the lateral position because the occurrence of epiglottic collapse substantially decreases in this position[17], 3) they were not flow limited, or 4) secretions blurred the endoscopic view.…”

Palatal prolapse as a signature of expiratory flow limitation and inspiratory palatal collapse in patients with obstructive sleep apnoea

“…Further studies are need to test whether the EFLI can help identify patients who respond to specific therapies, such as uvulopalatopharyngoplasty(40, 41), added nasal expiratory resistance therapy (Provent) (42), expiratory positive airway pressure (EPAP)(12, 13), mandibular advancement devices(43), positional therapy(44, 45), and upper airway stimulation therapy (46, 47). Our results show that palatal prolapse is more frequent in the supine than the lateral position.…”

Drug-Induced Sleep Endoscopy Findings in Supine vs Nonsupine Body Positions in Positional and Nonpositional Obstructive Sleep Apnea

“…In this study, DISE findings associated with changes in body position were broadly consistent with the law of gravity, consistent with our hypotheses. Intravenous propofol sedation has been shown to result in decreases in genioglossus tone (and presumably in other muscles), 12 so anteroposterior (anteroposterior velum-, tongue-, and epiglottis-related) airway narrowing would be expected in the supine body position and transverse (lateral velum-and oropharyngeal lateral wall-related) airway narrowing would be expected in the lateral body position. The 1 exception was that the changes with body position for lateral velum-and oropharyngeal lateral wall-related obstruction were not statistically significant overall and in the POSA subgroup.…”