Skin heating during simulated hemorrhage lowers arterial blood pressure but not tolerance following exercise in a cold environment.

Abstract

Skin heating helps avoid hypothermia in trauma victims but may influence systolic (SBP) and mean arterial blood pressures (MAP) helping guide resuscitation. We examined the effect of skin heating upon tolerance and arterial blood pressure during lower body negative pressure (LBNP) across four trials. Nine participants completed 15 exercise intervals (60 sec 88% PPO and 60 sec 10% PPO) in a cold environment (0°C, 70% RH) lowering mean skin temperature (Tsk) before undergoing LBNP to pre syncope where Tsk remained low (Cold Trial: 27.6 ± 1.1°C) or was increased via water perfused suit sixty seconds into LBNP to 32.3 ± 0.7°C (Normothermic Trial), 34.8 ± 0.4°C (Warm Trial) or 36.1 ± 0.8°C (Hot Trial). Tsk was different between trials (P = 0.001). Core temperature was not different between trials, increasing with exercise (36.9 ± 0.3°C to: 37.9 ± 0.4°C) and remaining elevated during LBNP (37.7 ± 0.4°C). During LBNP, MAP was greatest in the Cold (88 ± 7 mmHg) and relatively lowered in Normothermic (83 ± 5mmHg), Warm (82 ± 5mmHg) and Hot Trials (79 ± 7mmHg, all P ≤ 0.017 vs. Cold). SBP was greatest in Cold (111 ± 9mmHg) and Normothermic trials (110 ± 10mmHg) and relatively lowered in Warm (105 ± 7mmHg) and Hot trials (103 ± 11mmHg, both P ≤ 0.037). LBNP tolerance was not different between trials (P = 0.746). Following exercise in a cold environment, skin heating during simulated hemorrhage lowers arterial blood pressures and has implications for prehospital care of trauma victims.