Alveolar efficiency for CO2 in normal people and patients with chronic obstructive lung disease

: A simple test is described which measures the efficiency of the lungs in removing CO2. The test, initially described by Cumming et al. [5, 9], has been simplified to make it suitable for use in routine pulmonary function test laboratories. Results from 50 normal subjects are compared with values obtained from 20 patients with chronic airway obstruction. The alveolar efficiency for removing carbon dioxide was clearly impaired in this group of patients. The test is very easy to perform, even for patients with quite severe lung disease, and has the advantage of providing an indirect measure of arterial PCO2.