Rationale: Obstructive sleep apnea (OSA) is characterized by recurrent collapse of the upper airway during sleep. The relationship between upper airway collapsibility during wakefulness and sleep is poorly understood and may be influenced by the method of evaluation. Negative expiratory pressure (NEP) is usually applied through a mouthpiece while the subject is awake and seated. In contrast, pharyngeal critical closing pressure (Pcrit) is based on the application of variable nasal pressures during sleep in supine position. We hypothesized that the method of NEP determination (using mouthpiece while seated (NEP-sitting/mouth), mouthpiece while supine (NEP-supine/mouth) or nasal mask while supine (NEP-supine/mask)) influences NEP results and that NEP-supine/mask correlates with Pcrit. Methods: Twenty-eight men (age = 45±13 yr, body mass index = 28.2±4.0 kg/m2 and forced expiratory volume in the first second > 70% predicted) were evaluated by full overnight polysomnography (apnea-hypopnea index (AHI) = 24.8±21.2 - range 1.9 to 76.8 events/h), and NEP (-5cmH2O) using a mouthpiece while seated and supine as well as supine using a nasal mask. Pcrit was measured during midazolam-induced sleep (n=16). NEP was expressed by the exhaled volume at 0.2s after NEP application as a % of the mean inspiratory volume. Results: NEP-sitting/mouth, NEP-supine/mouth and NEP-supine/mask were 22.8±13.5%, 22.2±14.5% and 16.4±11.1%, respectively (n=28, p = 0.001). Post-hoc analysis revealed that the comparisons between NEP-supine/mask vs. NEP-sitting/mouth and NEP-supine/mask vs. NEP-supine/mouth were significantly different (p < 0.0001). NEP-supine/mask was correlated with Pcrit (r=-0.67, p=0.004), while NEP-supine/mouth and NEP-sitting/mouth were not (p=ns). Conclusions: The method of NEP determination influences the results. NEP-supine/mask while awake correlates with upper airway collapsibility during sleep as evaluated by Pcrit.
Comparison of upper airway collapsibility assessed by negative expiratory pressure while awake and critical closing pressure during sleep
Romano S;Insalaco G;
2013
Abstract
Rationale: Obstructive sleep apnea (OSA) is characterized by recurrent collapse of the upper airway during sleep. The relationship between upper airway collapsibility during wakefulness and sleep is poorly understood and may be influenced by the method of evaluation. Negative expiratory pressure (NEP) is usually applied through a mouthpiece while the subject is awake and seated. In contrast, pharyngeal critical closing pressure (Pcrit) is based on the application of variable nasal pressures during sleep in supine position. We hypothesized that the method of NEP determination (using mouthpiece while seated (NEP-sitting/mouth), mouthpiece while supine (NEP-supine/mouth) or nasal mask while supine (NEP-supine/mask)) influences NEP results and that NEP-supine/mask correlates with Pcrit. Methods: Twenty-eight men (age = 45±13 yr, body mass index = 28.2±4.0 kg/m2 and forced expiratory volume in the first second > 70% predicted) were evaluated by full overnight polysomnography (apnea-hypopnea index (AHI) = 24.8±21.2 - range 1.9 to 76.8 events/h), and NEP (-5cmH2O) using a mouthpiece while seated and supine as well as supine using a nasal mask. Pcrit was measured during midazolam-induced sleep (n=16). NEP was expressed by the exhaled volume at 0.2s after NEP application as a % of the mean inspiratory volume. Results: NEP-sitting/mouth, NEP-supine/mouth and NEP-supine/mask were 22.8±13.5%, 22.2±14.5% and 16.4±11.1%, respectively (n=28, p = 0.001). Post-hoc analysis revealed that the comparisons between NEP-supine/mask vs. NEP-sitting/mouth and NEP-supine/mask vs. NEP-supine/mouth were significantly different (p < 0.0001). NEP-supine/mask was correlated with Pcrit (r=-0.67, p=0.004), while NEP-supine/mouth and NEP-sitting/mouth were not (p=ns). Conclusions: The method of NEP determination influences the results. NEP-supine/mask while awake correlates with upper airway collapsibility during sleep as evaluated by Pcrit.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
