PULMONARY CAPILLARY BLOOD FLOW IN MAN 12

Abstract
A method is described for instantaneous measurement of pulmonary capillary blood flow in man. The subject sits in an airtight body plethysmograph; continuous records of plethysmograph pressure and the subject''s ecg are made during breathholding after N2O inhalation. As the N2O is absorbed by the blood flowing through the subject''s alveolar capillaries, the gas pressure within the body plethysmograph falls. The fall in pressure is proportional to the capillary blood flow and is pulsatile. The maximal rate of blood flow is in time with the T wave, while the slowest rate of flow closely follows the QRS complex.