A Modification of the Krogh Carbon Monoxide Breath Holding Technique for Estimating the Diffusing Capacity of the Lung; A Comparison With Three Other Methods 1

There are at present four methods for assessing the pulmonary diffusing capacity (D), one using 02 (Do2) and three using CO (Dco) namely, the 02 method of Lilienthal, Riley, Proemmel, and Franke (1), the steady state CO method of Filley, MacIntosh, and Wright (2) and the CO breath holding technique of Krogh and Krogh (3, 4) as modified by some of the authors (5), all of which provide estimates of the pulmonary diffusing ca- pacity, and finally the fractional CO uptake of Bates (6) which gives an index of pulmonary diffusing capacity. This is a report of a coopera- tive research effort to compare these methods as nearly simultaneously as possible on six patients and one normal subject. Measurements were made over the extremes of pulmonary diffusing capacity, from a patient with a severely decreased pulmonary diffusing capacity at rest (Subject 5) to a normal subject during exercise (Subject 1).