‘Air hunger’ from increased PCO2 persists after complete neuromuscular block in humans

doi:10.1016/0034-5687(90)90065-7

Respiration Physiology

Volume 81, Issue 1, July 1990, Pages 1-17

Respiration Physiolo...

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Abstract

The tolerance of totally curarized subjects for prolonged breath hold is viewed by many as evidence that respiratory muscle contraction is essential to generate the sensation of breathlessness. Although conflicting evidence exists, none of it was obtained during total neuromuscular block. We completely paralyzed four normal, unsedated subjects with vecuronium (a non-depolarizing neuromuscular blocker). Subjects were mechanically ventilated with hyperoxic gas mixtures at fixed rate and tidal volume. End-expiratory P_CO₂ (Pet_CO₂) was varied surreptitiously by changing inspired P_CO₂. Subjects rated their respiratory discomfort or ‘air hunger’ every 45 sec. At low Pet_CO₂ (median 35 Torr) they felt little or no air hunger. When Pet_CO₂ was raised (median 44 Torr) all subjects reported severe air hunger. They had reported the same degree of air hunger at essentially the same Pet_CO₂ before paralysis. When questioned afterwards all subjects said the sensation could be described by the terms ‘air hunger’, ‘urge to breathe’, and ‘shortness of breath’, and that is was like breath holding. They reported no fundamental difference in the sensation before and after paralysis. We conclude that respiratory muscle contraction is not important in the genesis of air hunger evoked by hypercapnia.

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‘Air hunger’ from increased PCO2 persists after complete neuromuscular block in humans

Abstract

Am. J. Med.

Respir. Physiol.

Breathlessness during different forms of ventilatory stimulation: a study of mechanisms in normal subjects and respiratory patients

Clin. Sci.

‘Air hunger’ arising from increased PCO2 in mechanically ventilated quadriplegics

Respir. Physiol.

Effects of Valsalva and Mueller maneuvers on breath-holding time

J. Appl. Physiol.

The effect of muscular paralysis induced by tubocurarine on the duration and sensation of breath-holding

Clin. Sci.

The effect of muscular paralysis induced by tubocurarine on the duration and sensation of breath-holding during hypercapnia

Clin. Sci.

Effects of changes in CO2 partial pressure on the sensation of respiratory drive

J. Appl. Physiol.

Integration of respiratory responses to changes in alveolar partial pressures of CO2 and O2 and in arterial pH

Breaking point of breath-holding

J. Appl. Physiol.

‘Air hunger’ from increased P_CO₂ persists after complete neuromuscular block in humans

‘Air hunger’ arising from increased P_CO₂ in mechanically ventilated quadriplegics

Effects of changes in CO₂ partial pressure on the sensation of respiratory drive

Integration of respiratory responses to changes in alveolar partial pressures of CO₂ and O₂ and in arterial pH