The air hunger response of four elite breath-hold divers.
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.
Binks
Andrew P
AP
Physiology Program, Department of Environmental Health, Harvard School of Public Health, and Department of Anesthesiology, Brigham & Women's Hospital, Boston, MA, USA. abinks@une.edu
Vovk
Andrea
A
Ferrigno
Massimo
M
Banzett
Robert B
RB
D000328:Adult; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000378:metabolism; D004242:Diving / Q000502:physiology*; D004417:Dyspnea / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D010313:Partial Pressure; D012123:Pulmonary Ventilation / Q000502:physiology; D012119:Respiration; D012121:Respiration, Artificial / Q000379:methods; D015656:Respiratory Mechanics / Q000502:physiology*; D012677:Sensation / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology; D013997:Time Factors; D014939:Work of Breathing
D002245:Carbon Dioxide
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