Face cooling increases blood pressure during central hypovolemia

Abstract

A reduction in central blood volume can lead to cardiovascular decompensation (i.e., failure to maintain blood pressure). Cooling the forehead and cheeks using ice water raises blood pressure. Therefore, face cooling (FC) could be used to mitigate decreases in blood pressure during central hypovolemia. We tested the hypothesis that FC during central hypovolemia induced by lower-body negative pressure (LBNP) would increase blood pressure. Ten healthy participants (22 ± 2 yr, three women, seven men) completed two randomized LBNP trials on separate days. Trials began with 30 mmHg of LBNP for 6 min. Then, a 2.5-liter plastic bag of ice water (0 ± 0°C) (LBNP FC) or thermo-neutral water (34 ± 1°C) (LBNP Sham) was placed on the forehead, eyes, and cheeks during 15 min of LBNP at 30 mmHg. Forehead temperature was lower during LBNP FC than LBNP Sham, with the greatest difference at 21 min of LBNP (11.1 ± 1.6 vs. 33.9 ± 1.4°C, P < 0.001). Mean arterial pressure was greater during LBNP FC than LBNP Sham, with the greatest difference at 8 min of LBNP (98 ± 15 vs. 80 ± 8 mmHg, P < 0.001). Cardiac output was higher during LBNP FC than LBNP Sham with the greatest difference at 18 min of LBNP (5.9 ± 1.4 vs. 4.9 ± 1.0 liter/min, P 0.005). Forearm cutaneous vascular resistance was greater during LBNP FC than LBNP Sham, with the greatest difference at 15 min of LBNP (7.2 ± 3.4 vs. 4.9 ± 2.7 mmHg/perfusion units (PU), P < 0.001). Face cooling during LBNP increases blood pressure through increases in cardiac output and vascular resistance.