Influence of negative airway pressure on upper airway dynamic and impact on night-time apnea worsening

Background: Negative airway pressure loading such as seen during obstructive apnea/hypopnea may influence upper airway (UA) mechanical properties. We measured the effects of such loading on UA mechanical properties during wakefulness and assessed the potential link with night-time apnea worsening. Methods: Twitch stimulations of the phrenic nerve were applied before and after a step-by-step increase in UA suction flow in 10 sleep apnea and 10 control males. Results: Inspiratory closing pressure was lower in control than in apneic subjects. No consistent changes were observed in UA mechanical properties before and after the trial. In apneic patients, changes in the apnea index from the beginning to the end of the night correlated with changes in inspiratory closing pressure following suction flow. Conclusion: (1) Apnea phenotype does not influence the impact of negative airway pressure on UA dynamic properties during wakefulness and (2) worsening of sleep apnea frequency during the night may relate to the exposure to recurrent UA negative pressure. (C) 2012 Elsevier B.V. All rights reserved.