Influence of gender on upper airway mechanics: upper airway resistance andPcrit

It has been proposed that the difference in sleep apnea prevalence is relat ed to gender differences in upper airway anatomy and physiology. To explain the prevalence difference, we hypothesized that men would have an increase d upper airway resistance and increased critical closing pressure (Pcrit) c ompared with women. In protocol 1, resistance at two points, fixed flow of 0.2 l/s (RL) and peak flow (Rpk), was measured in 33 men and 27 women witho ut significant sleep-disordered breathing. We found no difference in either RL (-6.9 +/- 5.9 vs. -8.6 +/- 8.2 cmH(2)O) or Rpk (-9.3 +/- 6.8 vs. -10.0 +/- 11.9 cmH(2)O) between the men and women. A multiple linear regression t o correct for the effects of age and body mass index confirmed that gender had no effect on resistance. In protocol 2, Pcrit was measured in eight men and eight women without sleep-disordered breathing. We found no difference in Pcrit (-10.4 +/- 3.1 vs. -8.8 +/- 2.7 cmH(2)O) between men and women. W e conclude that there are no significant differences in collapsibility betw een men and women. We present an unifying hypothesis to explain the diverge nt findings of gender differences in upper airway physiology.