Dl_CO measurements with gas chromatography

¹ Research Service, Wood Veterans Administration Center, and Departments of Medicine and Physiology, Marquette University School of Medicine, Milwaukee, Wisconsin

A gas chromatograph has been used to analyze gases for the measurement of pulmonary diffusing capacity using the breath-holding technique. The gas mixture used for the measurement consisted of carbon monoxide in air with neon as the insoluble inert gas. The calculated Dl_CO was unaffected when sulphur hexafloride (SF₆) or He was substituted for Ne in the mixture, but since CO and Ne could be most simply and rapidly analyzed, this combination was preferred for the gas mixture used to measure Dl_CO. The mean Dl_CO for ten normal subjects was 25.8 ± 4.2 ml/min mm Hg. These results were comparable to values reported in the literature when established methods of analysis were used. An excellent correlation was found between calculated Dl_CO and the clinical condition of patients with impaired pulmonary diffusing capacity.