The acute effect, of ethanol (EOH) include lowered blood pressure through peripheral vasodilation and decreased circulating blood volume. This study was aimed at examing the effects of EOH on the hemodynamic response to up and down head tilts.

Ten 21 to 23 year old male adults served as subjects. Each subject participated in both control and EOH experiments. In the EOH experiment, 3 mls of 25% EOH per liter of total body water was administered orally, 35 min were allowed for the blood EOH level to reach maximum before the tilt protocol was initiated. The tilt protocol consisted of 5 stages, each stage was 3-min in duration : supine (0 degrees)-head down tilt (HDT, 15 degrees)-supine (0 degrees)-head up tilt (HUT, 25 degrees)-supine (0 degrees). Hemodynamic parameters were measured with an impedance cardiograph (NCCOM3-R7, BoMed) with two electrodes placed around the neck and two around the thorax. Blood pressure (BP) was measured with an automatic sphygmomanometer (DATEX). Data was collected during every second half-minute throughout the duration of the protocol.

In the control, HDT produced an increase in the end-diastolic index (EDI), the stroke index (SI), the cardiac index (CI), and the peak flow index (PFI) ; there were no significant changes in heart rate (HR), the systemic vascular resistance index (SVRI), and BP. In contrast, HUT resulted in a decrease in EDI, SI, EF, CI, and PFI and an increase in HR, SVRI, and BP ; the latter changes sugges a sympathetic overactivation. In the EOH experiment, the basal EDI, SI, and systolic BP were lower and HR was higher than in control. HDT and HUT caused similar changes as in control experiments.

There results indicate that EOH cause volume depletion to result in reduced central blood volume and compensatory tachycardia. These EOH-induced changes were not altered by 15 degreeshead-down and 25 degreeshead-up tilts.