Mechanisms used to restore ventilation after partial upper airway collapse during sleep in humans

Jordan S, Wellman A, Heinzer R, Lo Y, Schory K, Dover L, Gautam S, Malhotra A, White D

Most patients with obstructive sleep apnoea (OSA) can restore airflow after an obstructive respiratory event without arousal. The aims of this study were to compare the ability to recover ventilation and the mechanisms of compensation following a sudden reduction of continuous positive airways pressure (CPAP) in subjects with and without OSA.

10 obese patients with OSA and 15 healthy non-snorers were instrumented with intramuscular genioglossus electrodes and a mask/pneumotachograph connected to a CPAP device that could deliver positive or negative pressure.

During reduced CPAP the increase in genioglossus activity in subjects with OSA and in non-snorers were similar, yet patients with OSA could restore ventilation without cortical arousal  less often than non-snorers. When ventilatory recovery did not occur, genioglossus muscle and respiratory timing changes still occurred but these did not yield adequate pharyngeal ventilation.

Compensatory mechanisms often restore ventilation during sleep but may be less effective in obese patients with OSA than in non-snorers.

Thorax 2007, 62: 868-872

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