Ventilation and perfusion of the lungs before and during blockade of one of the main bronchi

An attempt has been made to evaluate the magnitude of and changes in the right-left shunt following 40 minutes' blockade of one of the main bronchi in 6 anaesthetized patients, of whom 3 had the right and 3 the left bronchus blocked. Xenon133 was used together with a simple transportable apparatus employing four collimators on the anterior of the thorax. Despite verified blockade (bronchoscopy and stethoscopy), the study showed an activity corresponding to a ventilation of approximately one-third of the initial values. It was not possible to demonstrate any fall in the perfusion on the blocked side following blockade of the left main bronchus, whereas blockade of the right main bronchus produced a calculated fall to two-thirds of the initial perfusion. The blockade caused a fall in PaO2 in all the patients, which was inpendent upon the side blocked and of a magnitude that corresponded to the perfusion measured after blockade of the right main bronchus.