The air hunger response of four elite breath-hold divers

Respir Physiol Neurobiol. 2007 Nov 15;159(2):171-7. doi: 10.1016/j.resp.2007.06.014. Epub 2007 Jul 1.

Abstract

Normal subjects terminate breath-holds due to intolerable 'air hunger'. We hypothesize that competitive breath-hold divers might have increased tolerance of air hunger. We tested the air hunger (AH) response of four divers who could hold their breath for 6-9 min. Tidal volume and respiratory rate were controlled by mechanical ventilation (ventilation approximately 0.16 L min(-1) kg(-1)). AH was induced by raising PCO2 and rated using a visual analog scale whose maximum was defined as intolerable. SpO2 was maintained at >97%. Three divers reported the same uncomfortable urge to breathe as normal subjects; the slopes of their responses were within normal range. Both resting CO2 and AH threshold were shifted to higher CO2 in some divers. Diver 3 was unique amongst neurologically intact subjects we have studied: he denied feeling an urge to breathe, and denied discomfort. We conclude that elite divers' strategies to tolerate intense air hunger are a minor factor in their ability to tolerate long breath-holds.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Gas Analysis
  • Carbon Dioxide / metabolism
  • Diving / physiology*
  • Dyspnea / physiopathology
  • Female
  • Humans
  • Male
  • Partial Pressure
  • Pulmonary Ventilation / physiology
  • Respiration*
  • Respiration, Artificial / methods
  • Respiratory Mechanics / physiology*
  • Sensation / physiology
  • Tidal Volume / physiology
  • Time Factors
  • Work of Breathing*

Substances

  • Carbon Dioxide