The effects of psychological stress on respiration: a preliminary study of anxiety and hyperventilation.

TLDR: It is suggested that respiration rate alone is an insufficient measure of respiratory reactivity to psychological stimuli and more appropriate functional assessments of respiratory response to stress are discussed.

Abstract: The occurrence of hyperventilation (overbreathing resulting in lowered end-tidal CO2) in conjunction with psychological stress was investigated. Twenty-nine normal subjects were individually placed in a stress condition by being required to make perceptual judgments under threat of electric shock for exceeding a specified number of errors. Feedback of errors was controlled by the experimenter and no subject was ever shocked since manipulated feedback never exceeded shock criterion. Stress induction consisted of four phases: request for participation, subject decision, pre-task instruction, and task. Dependent measures consisted of end-tidal CO2, respiration rate, heart rate, and State Anxiety scores. Stress manipulation was confirmed by significantly increased heart rate and anxiety scores from baseline values. Baseline comparisons indicated significant decreases in end-tidal CO2 (i.e., hyperventilation) for all phases as well as significant increases in respiration rate for all phases but one. Comparisons among several phases revealed significant changes in end-tidal CO2 either unaccompanied by or uncorrelated with changes in respiration rate. These results: 1) support the occurrence of hyperventilation to stress in normals, 2) suggest that respiration rate alone is an insufficient measure of respiratory reactivity to psychological stimuli, and 3) are discussed in terms of more appropriate functional assessments of respiratory response to stress.