Menzies Health Institute Queensland, Gold Coast, QLD, AUSTRALIA.
Med Sci Sports Exerc. 2018 Mar;50(3):417-426. doi: 10.1249/MSS.0000000000001455.
Heart failure (HF) patients seem to exhibit altered thermoregulatory responses during exercise in the heat. However, the extent to which these responses are altered due to physiological impairments independently of biophysical factors associated with differences in metabolic heat production (Hprod), evaporative heat balance requirements (Ereq), and/or body size is presently unclear. Therefore, we examined thermoregulatory responses in 10 HF patients and 10 age-matched controls (CON) similar in body size during exercise at a fixed rate of Hprod and therefore Ereq in a 30°C environment.
Rectal temperature, local sweat rate, and cutaneous vascular conductance were measured throughout 60 min of cycle ergometry. Whole-body sweat rate was estimated from pre-post nude body weight corrected for fluid intake.
Despite exercising at the same rate of Hprod (HF, 338 ± 43 W; CON, 323 ± 31 W; P = 0.25), the rise in rectal temperature was greater (P < 0.01) in HF (0.81°C ± 0.16°C) than in CON (0.49°C ± 0.27°C). In keeping with a similar Ereq (HF, 285 ± 40 W; CON, 274 ± 28 W; P = 0.35), no differences in whole-body sweat rate (HF, 0.45 ± 0.11 L·h; CON, 0.41 ± 0.07 L·h; P = 0.38) or local sweat rate (HF, 0.96 ± 0.17 mg·cm·min; CON, 0.79 ± 0.15 mg·cm·min; P = 0.50) were observed between groups. However, the rise in cutaneous vascular conductance was lower in HF than in CON (HF, 0.83 ± 0.42 au·mm Hg; CON, 2.10 ± 0.79 au·mm Hg; P < 0.01). In addition, the cumulative body heat storage estimated from partitional calorimetry was similar between groups (HF, 154 ± 106 kJ; CON, 196 ± 174 kJ; P = 0.44).
Collectively, these findings demonstrate that HF patients exhibit a blunted skin blood flow response, but no differences in sweating. Given that HF patients had similar body heat storage to that of CON at the same Hprod, their greater rise in core temperature can be attributed to a less uniform internal distribution of heat between the body core and periphery.
心力衰竭（HF）患者在热环境中运动时似乎表现出改变的体温调节反应。然而，这些反应在多大程度上由于与代谢产热（Hprod）、蒸发散热平衡需求（Ereq）和/或身体大小差异相关的生理损伤而改变，目前尚不清楚。因此，我们在 30°C 环境中以固定的 Hprod 率（因此也是 Ereq）进行运动时，检查了 10 例 HF 患者和 10 例年龄匹配的对照组（CON）的体温调节反应。
在 60 分钟的踏车运动过程中测量直肠温度、局部排汗率和皮肤血管传导性。全身排汗率根据裸体前后的体重减去液体摄入进行校正。
尽管以相同的 Hprod 率（HF，338 ± 43 W；CON，323 ± 31 W；P = 0.25）进行运动，但 HF 组的直肠温度升高幅度更大（P < 0.01）（HF，0.81°C ± 0.16°C；CON，0.49°C ± 0.27°C）。由于相似的 Ereq（HF，285 ± 40 W；CON，274 ± 28 W；P = 0.35），两组之间的全身排汗率（HF，0.45 ± 0.11 L·h；CON，0.41 ± 0.07 L·h；P = 0.38）或局部排汗率（HF，0.96 ± 0.17 mg·cm·min；CON，0.79 ± 0.15 mg·cm·min；P = 0.50）均无差异。然而，HF 组的皮肤血管传导性升高幅度低于 CON 组（HF，0.83 ± 0.42 au·mm Hg；CON，2.10 ± 0.79 au·mm Hg；P < 0.01）。此外，从分区热量计估计的累积体热储存量在两组之间相似（HF，154 ± 106 kJ；CON，196 ± 174 kJ；P = 0.44）。
综上所述，这些发现表明 HF 患者表现出皮肤血流反应迟钝，但排汗无差异。鉴于 HF 患者在相同的 Hprod 下与 CON 具有相似的体热储存量，他们核心温度的升高幅度更大可能归因于身体核心和外周之间热量的分布不均。
