Ventilatory response to carbon dioxide in humans.

Testing ventilatory responses to CO2 is fraught with difficulties in interpretation and, at present, it can hardly be considered suitable for routine evaluation of patients with pulmonary disease. In spite of the seventy years' work since Haldane's introduction of the CO2 response curve, much remains to be learned about the various components of the regulatory system, and for testing chemosensitivity to CO2 in patients with pulmonary disease, methods more direct than measuring pulmonary ventilation are needed for evaluation of the output of the regulatory system.