Measurement of cerebral blood flow by ultrasonic Doppler technique--cerebral hemodynamics during voluntary hyperventilation and the valsalva maneuver

Position modifies carotid artery blood flow velocity during straining

The Valsalva maneuver (VM) produces rapid shifts in cerebrovascular blood flow and is often implicated in aneurysm rupture and rebleeding. To determine whether intensity of hemodynamic shifts is affected by position, we examined effects of five body positions (chair, 70 degrees and 30 degrees upright, flat, side) on carotid artery blood flow velocity (CABFV) across the VM in 141 healthy adults (30-55 yrs.). Subjects strained at 40 mmHg pressure for 10 seconds. CABFV was measured continuously by ultrasonic Doppler technique. During straining, position significantly (F = 13.7; p less than .0001) affected CABFV. Less reduction occurred in the chair (p less than .05) position than in any of the others. The 70 degrees position produced less fall in CABFV (p less than .05) than did the 30 degrees, flat and side positions. Less increase in CABFV across the VM was recorded in the chair position (p less than .05) than in any of the others. It is concluded that the chair position can be used therapeutically to reduce severe shifts of CABFV associated with straining.

Ethnic differences in physiological responses associated with the Valsalva maneuver

Ethnic differences in cardiovascular indices at rest and across the Valsalva maneuver (VM) were studied in 30 Asian, 86 Caucasian, and 12 Black healthy men and women aged 30 to 55 years. Subjects simulated the VM by blowing into an aneroid pressure-gauge meter to 40 mmHg for 10 seconds. Resting systolic blood pressure (SBP) was significantly higher in Blacks than in Asians or Caucasians. During the strain phase of the VM, the fall in SBP from baseline was significantly greater in Asians and Blacks than in Caucasians. Further, Asians had the greatest overshoot of SBP above baseline. Although resting heart rate was significantly higher in Asians compared to Caucasians, there were no differences in heart rate responses to the VM. Reduction in carotid artery blood flow velocity during strain was significantly less in Blacks. We conclude that there are ethnic differences in cardiovascular indices at rest and across the VM.

Circulatory response in Aschner and Czermak-Hering tests, with special reference to cerebral circulation

The Aschner and Czermak-Hering tests were carried out in 7 normal young males and 15 elderly patients with cerebral arteriosclerosis. Alterations in the heart rate, blood pressure and blood flow in the internal carotid artery and brachial artery were studied by means of the on-line Doppler ultrasonic apparatus before, during and after the maneuvers, simultaneously and continuously. Aschner Test. Bradycardia, biphasic alteration of blood pressure, increase of blood flow in the internal carotid artery and decrease of blood flow in the brachial artery were observed in the maneuver. The changing rate of the findings was diversified individually. However, no significant difference was observed between the normal young males and the elderly patients. Side effects consisted of slight and transient nausea and dizziness in 6 subjects. Czermak-Hering Test. Bradycardia, hypotension, and decrease of blood flow in the brachial artery were observed in the maneuver. The changing rate of the findings is more conspicuous in the elderly patients than in the normal young males. Alterations in the blood flow in the internal carotid artery were observed. There was a conspicuous increase of the blood flow in the internal carotid artery on the noncompressed side during the maneuver in all the normal young males and in half of the elderly patients. The remainder of the elderly patients showed either no alteration or decrease of the blood flow in the internal carotid artery on the noncompressed side. Slight nausea in 2 subjects, slight dizziness in 5 subjects, and moderate disturbance of consciousness in 1 subject were observed as side effects. The results indicate that the Czermak-Hering test will be more advantageous in investigating the autonomic nervous function (vasovagal reflex) and autoregulation of cerebral circulation in elderly subjects.

Circulatory effect of respiratory maneuvers

The circulatory effects of three kinds of respiratory maneuvers--maximum breathing, voluntary hyperventilation, and the Valsalva maneuver--on cerebral blood flow, brachial blood flow, heart rate, and systolic blood pressure were investigated by means of the on-line Doppler ultrasonic technique in 20 men. Arterial gas contents (PO2, PCO2, pH) were also examined. Cerebral blood flow was increased or showed the biphasic response (increase in the former and decrease in the latter part of the maneuver) with maximum breathing. Cerebral blood flow was decreased with voluntary hyperventilation. The cerebral blood flow was maintained at a same level during the maneuver or tended to return to the control level. Cerebral blood flow was decreased in the Valsalva maneuver. There was a transient but conspicious increase of the cerebral blood flow immediately after the maneuver.