The electrocardiogram as a diagnostic aid in pneumothorax.

This study shows that during some common activities, there appears to be shallow, irregular breathing involving both chest and diaphragmatic movement, and this is followed by a period of increased ventilation. It is possible that during the activity, there is some carbon dioxide rentention and possibly a fall in arterial oxygen tension. Hyperventilation after the activity is needed to return the blood gases towards the previous resting level. This increased breathing following the activity is appreciated as dyspnea in patients with obstructive lung disease. In normal subjects, compensation for the shallow, irregular breathing is achieved by a few deep breaths which are easily performed without subjective discomfort. Patients become fearful when they find themselves short of breath after such minor exertion as doing their hair, and explanation that this is due to a breathing pattern, which they can personally observe, can do much to reassure them and eliminate unnecessary fear of their disease. S . Tangri, M.D. and C . R . Woolf,M.D.,F.C.C.P.* Toronto, Ontario