PHYSIOLOGICAL STUDIES OF FAINTNESS AND SYNCOPE

Abstract

Physiological changes preceding and coincident with sensations of faint-ness have been studied in 6 experiments in 4 healthy d1 subjects. Before the sensations of faintness the pulse rate rose, but the respiration, blood pressure and cardiac output remained normal. At or soon after the beginning of faintness the volume of respiration began to increase and the alveolar CO2 tension diminished, but at this stage normal blood pressure was found. Later, during syncope, a profound fall of pulse rate and blood pressure occurred.