Some cardio-pulmonary effects of infra-renal clamping of the abdominal aorta.

No significant changes were found in heart rate, blood pressure, cardiac output, arterial blood gases or physiological deadspace: tidal volume ratio before and after clamping and unclamping the abdominal aorta below the renal vessels. Nevertheless, drugs should be available to reduct the afterload on the heart if any evidence of myocardial ischaemia appears during the period of aortic clamping. The importance of maintaining an adequate circulating blood volume at all times is stressed.