E. Savin

Vasomotor Effects of Transcutaneous CO2 in Stage II Peripheral Occlusive Arterial Disease

Vasomotor effects of skin exposure to carbon dioxide (CO2) have been described in normal subjects. It was of interest, therefore, to determine whether percutaneous CO2 is of therapeutic benefit. In a randomized, double-blind study, 10 patients with lower limb arteriopathy (stage II) were investigated before and after local exposure for twenty minutes to CO2-rich spa gas or to water-vapor-saturated air at the same temperature as that CO2 -rich spa gas. Brachial and femoral blood flows, brachial and posterior tibial artery pressures, heart rate, and chest and foot transcutaneous oxygen tensions (tcPO2) were determined. Femoral blood flow, tibial pressure, and foot tcPO2 were significantly increased after exposure of the skin to CO2-rich spa gas. This effect was not accompanied with systemic hemodynamic modifications. Water-vapor-saturated air had no effect. These results suggest that transfer of CO2 across the skin can have beneficial local vasomotor effects in patients with lower limb stage II arteriopathy.

Influence of posture on middle cerebral artery mean flow velocity in humans

We determined middle cerebral artery, common carotid artery and temporal superficial artery Doppler derived flow velocities in ten subjects for 10 min after change in posture. Maximal changes were observed after about 3 min. The 10° head-down tilt position increased blood velocities in the common carotid artery by 13% (SD 4)% (P < 0.001), in the middle cerebral artery by,6% (SD 3)% (P < 0.001) and in the superficial temporal artery by 70% (SD 26)% (P < 0.001). In the standing position, there was an 18% (SD 9)% (P < 0.001) decrease in the common carotid blood velocities, with 14% (SD 6)% (P < 0.001) and 53% (SD 23)% (P < 0.001) reductions in the middle cerebral and superficial temporal artery velocities, respectively. At 9 min after the changes in posture, velocities in the middle cerebral artery were at the value of supine rest, whereas the common carotid blood velocity was not completely restored and deviations in the temporal artery velocity persisted. The data would suggest that cerebral blood flow is regulated with some delay and that such regulation is partially reflected in the common artery blood flow, since changes in a branch of the external carotid artery flow velocity remained.

Evidence of fetal cerebral vasodilatation induced by submaximal maternal dynamic exercise in human pregnancy

To investigate the relationship between maternal exercise and fetal circulatory responses in humans during the third trimester of pregnancy, changes in uterine, umbilical and fetal cerebral circulations were measured by pulsed-Doppler ultrasound method in 14 healthy volunteer pregnant women before and just after a moderate non-exhaustive exercise. Maternal heart rate increased significantly reaching 80% of the theoretical maximal heart rate (TMHR) while uterine resistance indices did not change. The fetal heart rate and umbilical mean velocity were unchanged while umbilical resistance index decreased slightly (0.58 +/- 0.06 versus 0.62 +/- 0.07, P < 0.05). The fetal internal carotid artery mean velocity increased (23.2 +/- 5.3 versus 20.4 +/- 4.1 cm/s, P < 0.02) and the cerebral resistance index decreased (0.71 +/- 0.11 versus 0.80 +/- 0.10, P < 0.01). We conclude that submaximal maternal exercise at 80% of TMHR does not significantly alter uterine perfusion but involves a slight fetal cerebral vasodilation which could be due to a moderate fetal hemoglobin desaturation.

Intra- and extracranial artery blood velocity during a sudden blood pressure decrease in humans

The intra- and extracerebral Doppler artery blood velocity responses to a 10-mmHg abrupt blood pressure (BP) decrease in ten healthy men were studied. This decrease was obtained using two cuffs placed over both thighs. First, cuffs were inflated to pressures greater than the arterial BP for 5 min. Next, they were deflated to 60 mmHg in order to prevent venous return from the legs. We obtained a decrease in mean arterial BP of from 101 (10) to 90 (10) mmHg [mean (SD), P < 0.01] without modifications in the heart rate [HR, 88 (14) beats min−1]. Middle cerebral artery mean blood velocity (MCAmv) decreased immediately from 50 (10) to 42 (12) cm s−1 (P < 0.05). Simultaneously, temporal superficial artery mean blood velocity (TSAmv) decreased from 11 (3) to 7 (2) cm s−1 (P < 0.05) and common carotid artery blood flow (CCAbf ) decreased from 305 (23) to 233 (33) ml min−1 (P < 0.05). After 5 s, MCAmv and CCAbf returned to baseline values, whereas TSAmv [8 (2) cm s−1], mean arterial BP [86 (10) mmHg] remained low and HR increased [92 (12) beats min−1]. TSAmv, BP and HR returned to baseline values in 1 min. These data confirm that cerebral blood flow (CBF) is very rapidly regulated but that blood flow in extracranial territories is not and that it follows the arterial BP changes.