Resting end-tidal CO2 and negative affectivity.

Objective: Dhokalia, Parsons, and Anderson (Psychosom Med 1998;60:33-37) found a positive correlation between a trait measure of negative affectivity (NA; neuroticism) and resting end-tidal fractional concentration of CO2 (FetCO2) (fractional-concentration of end-tidal carbon dioxide) in a nonclinical sample. This contrasts sharply with studies reporting a negative association of FetCO2 with state measures of NA and with studies reporting no or a negative relationship between FetCO2 and trait NA. In two studies we aimed to clarify this paradox.