The evaluation of blood flow measurement using gravimetric plethysmograph.

Abstract

Summary The gravimetric plethysmograph is a simple, robust and inexpensive device which measures blood flow in the limb in terms of the increase in weight which follows temporary venous occlusion. Validation of the instrument using an artificial circuit shows that it is accurate and gives reproducible results. The mean resting blood flow in the legs of 18 healthy volunteers was 3·95 ml 100 ml−1 tissue min−1 and this measurement was not reproducible. A 3-min period of arterial occlusion resulted in an immediate hyperaemic response of a mean 43·5 ml 100 ml−1 min−1, and this result was much more reproducible (r = 0·18). The mean resting blood flow of 45 patients with occlusive arterial disease of the legs was 2·1 ml 100 ml−1 min−1, and this flow rate was variable (r = 0·71). Their immediate hyperaemic response of 5·18 ml 100 ml−1 min−1 was much less than that in normal volunteers, but was quite reproducible (r = 0·93). Following arterial reconstruction, their mean immediate hyperaemic response rose to 10·35 ml 100 ml−1 min−1, which was a significant increase compared to their preoperative values (P < 0·0005, Student's t test) and was associated with concomitant improvement in symptoms, treadmill performance and ankle/brachial systolic pressure indices. Measurement of the immediate hyperaemic response to temporary arterial occlusion with the gravimetric plethysmograph may assist in the evaluation of patients with occlusive arterial disease of the legs, and in their medical and surgical management.