Zur Methodik der venösen Okklusionsplethysmografie. Die Wirkung distaler Gefässokklusion auf die Durchblutung im Unterarm

The influence of age on reactive hyperaemia in the human calf: a study with strain gauge plethysmography

Postischaemic reactive hyperaemia in the calf was investigated by strain gauge plethysmography in four groups of ten subjects. The mean age of the different groups was 6, 13, 24 and 57 years respectively. Basal calf flow, repayment and recovery time in the 6-year-old children were greater than in the other groups, which may be related to a higher metabolic rate in young children. Maximal flow in the four groups was not significantly different, which indicates that the arteriolar response to circulatory arrest is not altered by increasing age. The cause of delay in maximal flow in the group of 6-year-olds is not clearly understood. Basal and postischaemic lowest peripheral resistance increased with age, which is probably caused by changes of the arterioles due to ageing and possibly inactivity. The fall in peripheral resistance induced by 3 min of ischaemia was positively correlated with mean blood pressure. This may be due to a greater net reduction in blood pressure during ischaemia, which brobably elicits a stronger myogenic response of the vessel wall. It is concluded that in clinical use of the reactive hyperaemia test in the calf, the influence of age is of minor importance, whereas postischaemic peripheral resistance is a more accurate measure of vasocilation for comparison of subjects with different blood pressure.

Effect of dihydroergotamine on perpheral circulation during epidural anaesthesia in man

The effect of intravenous administration of dihydroergotamine (DHE) on regional blood flow in the forearm and calf after pharmacological nerve blockade of the lower body induced by epidural anaesthesia has been studied in 13 subjects. After anaesthesia, DHE induced a significant increase in blood flow in the forearm with intact innervation and a significant decrease in blood flow in the nerve-blocked calf. On the average, the arterial blood pressure increased slightly. The calculated local vascular resistance increased in the nerve-blocked calf, probably due to a direct myogenic constrictive effect of DHE. In the intact forearm, local vascular resistance decreased. The results indicate that DHE exerts a complex effect on resistance vessels in addition to its well-known effect on the capacitance vessels.

Studies of the central and peripheral hemodynamic effects of amyl nitrite in patients with aortic insufficiency

The cardiovascular reaction induced by amyl nitrite was studied in a main group of 11 patients with pronounced and isolated aortic insufficiency, and in an additional and more heterogeneous group of seven patients with moderate aortic insufficiency combined with other lesions, by measuring left ventricular end-diastolic pressure, systemic and peripheral arterial pressures, cardiac output, peripheral blood flow, and venous tone.

Total peripheral resistance decreased, but local vascular resistance differed significantly between the upper and the lower extremities. In most cases arterial dilatation in the forearm (mainly muscle) was found. Simultaneously, there was uniform vasoconstriction in the calf (mainly muscle) which was interpreted to be secondary (baroreceptor reflex). This regional difference in circulatory reaction was also manifested in a pronounced change of the contour of the brachial arterial pulse, while the femoral arterial pulse was practically unchanged. The hand blood flow (skin) decreased while the foot blood flow did not change significantly.

A marked fall in systemic arterial pressure and in left ventricular end-diastolic pressure was clearly demonstrated, and secondarily there was a rise in heart rate as well as a pronounced venoconstriction in both the upper and lower extremities, also interpreted to be secondary (a baroreceptor reflex). There was good correlation between maximal increase in heart rate and maximal increase in venous tone and also between the augmentation in heart rate and cardiac output. An elevation in stroke volume was noted in most cases. The reaction to amyl nitrite was not significantly different in the two groups of patients.