Upper airway mechanics and post-hypoxic ventilatory decline during NREM sleep

R. B. Halker, L. A. Pierchala, M. S. Badr

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Termination of hypoxia results in a transient ventilatory decline referred to as post-hypoxic ventilatory decline (PHVD). We wished to determine whether PHVD is due to changes in ventilatory motor output or upper airway mechanics. We studied 19 healthy normal subjects (15 men, 4 women) during stable non-REM (NREM) sleep. Subjects were exposed to multiple episodes of brief (3 min) hypoxia that terminated with one breath of 100% FIO2. Minute ventilation (VI), tidal volume (VT), timing, and upper airway resistance (Rua) were measured during the control, hypoxia, and for the first six breaths immediately after cessation of hypoxia. In addition, we measured diaphragmatic electromyograms (EMGdia) via surface electrodes in four subjects. VI and VT decreased during the recovery period to a nadir of 81and 83% of room air control, respectively. However, there was no significant change in respiratory frequency or upper airway resistance during the post-hypoxic recovery period. Decreased VI was associated with a comparable decrease in EMGdia. We conclude that: (1) PHVD occurs in normal humans during NREM sleep, (2) there is no evidence of post-hypoxic frequency decline in humans during NREM sleep, and (3) PHVD is centrally mediated and not driven by upper airway mechanics.

Original languageEnglish (US)
Pages (from-to)165-170
Number of pages6
JournalSleep and Breathing
Issue number3
StatePublished - Sep 2007


  • Control of ventilation
  • Hypoxia
  • Sleep
  • Upper airway resistance

ASJC Scopus subject areas

  • Otorhinolaryngology
  • Clinical Neurology


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