To the Editor.
—I was very interested in Dr. Bogdonoff's editorial on undiagnosed distress 1 and the recent further comment by Albert B. Craig, Jr., MD.2 The original editorial suggested that some patients might have a detection system more sensitive than that of the medical profession and Dr. Craig has amplified this and speculates that rather than being qualitatively different "hyper-reactors," these individuals might be at one end of a normal distribution for responsiveness or tolerance to certain specific physiological stresses.Several years ago, J. H. Auchincloss, Jr., MD, and I made a study of otherwise normal women in whom severe dyspnea developed early in their pregnancy.3 As part of that study we tested the ventilatory response to inhaled 5% carbon dioxide in air in these women at a time when they were not pregnant. We found that those women in whom this type of dyspnea developed had