A negative expiratory pressure test during wakefulness for evaluating the risk of obstructive sleep apnea in patients referred for sleep studies

Abstract

OBJECTIVE: Obstructive sleep apnea is characterized by increased upper airway collapsibility during sleep. The present study investigated the use of the negative expiratory pressure test as a method to rule out obstructive sleep apnea.METHODS:Flow limitation was evaluated in 155 subjects. All subjects underwent a diurnal negative expiratory pressure test and a nocturnal sleep study. The severity of sleep apnea was determined based on the apnea-hypopnea index. Flow limitation was assessed by computing the exhaled volume at 0.2, 0.5, and 1.0 s (V0.2, V0.5, and V1.0, respectively) during the application of a negative expiratory pressure and expressed as a percentage of the previous exhaled volume. Receiver-operating characteristic curves were constructed to identify the optimal threshold volume at 0.2, 0.5, and 1.0 s for obstructive sleep apnea detection.RESULTS: Mean expiratory volumes at 0.2 and 0.5 s were statistically higher (p<0.01) in healthy subjects than in all obstructive sleep apneic groups. Increasing disease severity was associated with lower expiratory volumes. The V0.2 (%) predictive parameters for the detection of sleep apnea were sensitivity (81.1%), specificity (93.1%), PPV (98.1%), and NPV (52.9%). Sensitivity and NPV were 96.9% and 93.2%, respectively, for moderate-to-severe obstructive sleep apnea, and both were 100% for severe obstructive sleep apnea.CONCLUSION: Flow limitation measurement by V0.2 (%) during wakefulness may be a very reliable method to identify obstructive sleep apnea when the test is positive and could reliably exclude moderate and severe obstructive sleep apnea when the test is negative. The negative expiratory pressure test appears to be a useful screening test for suspected obstructive sleep apnea.

Upper Airway Collapsibility Assessed by Negative Expiratory Pressure while Awake is Associated with Upper Airway Anatomy

“…The majority of studies applied NEP using a mouthpiece either while sitting or supine. 15,16,18,[28][29][30][31][32] This technique was adapted from earlier studies that aimed to evaluate intrathoracic obstruction. 13,14,33 However, the use of a mouthpiece excludes the retropalatal region that is a common site of obstruction during sleep in patients with OSA.…”

Pesquisas em pneumologia recentemente publicadas em revistas brasileiras

“…According to Romano et al, (53) the determination of flow limitation (exhaled air volume in 0.2 s) by a negative expiratory pressure test during wakefulness might be a highly sensitive and reliable method of identifying OSA. When the test is positive, mild OSA can be presumed; when it is negative, moderate and severe OSA can be excluded.…”

Pneumological research in Clinics

“…Romano et al (35) report that flow limitation measurement during wakefulness is a highly sensitive and reliable method for identifying obstructive sleep apnea when the test is positive and that this approach may reliably exclude moderate and severe obstructive sleep apnea when the test is negative.…”