A standardised method of estimating KCO on exercise.

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Abstract
A progressive exercise test for the assessment of change in CO transfer coefficient (KCO) [abnormal pulmonary function index] with exercise was standardized and the variation between subjects and the reproducibility within subjects were examined. Normal subjects exercised on a bicycle ergometer while ventilation, heart rate and expired gas concentrations were recorded continuously. Reduction of the breath hold time to 6 s made measurements of KCO during heavy exercise more comforable without affecting the result. When KCO was measured immediately after exercise it was lower than when measured during exercise. KCO was measured in 50 normal subjects at rest and at 3 different work loads maintained for 3 min with a pause of 5 min between each. The relationships between KCO and both O2 consumption [.ovrhdot.VO2] and work load were linear in all subjects but the relationship between KCO and heart rate was distorted by high resting heart rates in some subjects. The mean slope of the relationship between KCO and O2 VO2 was steeper in women than in men (mean slopes 0.627 and 0.348 mmol min-1 kPa[paschol]-1 1-1, per 1 min-1 respectively), and the same was true for the relationship between KCO and work rate. The heart rate rose more steeply in relation to .ovrhdot.VO2 in women, so that the relationship of KCO to heart rate was similar in men and women (mean slope 0.01 mmol min-1 kPa-1 per beat min-1). Repeat studies on 5 occasions in 5 individuals gave coefficients of variation for the slopes of the relationships between KCO and .ovrhdot.VO2 work rate, and heart rate of 5-10%.