The influence of lateral tilt on limb blood flow in advanced pregnancy.

Blood flow of the forearm and calf were measured in 20 expectant mothers by means of strain gauge plethysmography. Measurements were made with the patients initially lying supine, then tilted to the right or left side with a 15 degrees foam rubber wedge and, finally, after returning the subjects to the supine position. Blood flow of the forearm was unaltered by changes in maternal posture. Lower limb perfusion usually increased significantly when the mothers assumed the right or left lateral tilt position, and decreased when the patients again lay supine. The significance of these findings in relationship to aortocaval occlusion by the gravid uterus is discussed. We conclude that lateral tilt of the patient during Caesarean section should contribute significantly to the safety and welfare of both mother and infant.