Falk Bareket, Dotan Raffy
Faculty of Applied Health Science, Brock University, St Catharines, ON, Canada.
Appl Physiol Nutr Metab. 2008 Apr;33(2):420-7. doi: 10.1139/H07-185.
The review revisits some child-adult differences relevant to thermoregulation and offers alternatives to accepted interpretations. Morphologically, children have a higher body surface area to mass ratio -- a major factor in "dry" heat dissipation and effective sweat evaporation. Locomotion-wise, children are less economical than adults, producing more heat per unit body mass. Additionally, children need to divert a greater proportion of their cardiac output to the skin under heat stress. Thus, a larger proportion of their cardiac output is shunted away from the body's core and working muscles -- particularly in hot conditions. Finally, under all environmental conditions and allometric comparisons, children's sweating rates are lower than those of adults. The differences appear to suggest thermoregulatory inferiority, but no epidemiological data show higher heat-injury rates in children, even during heat waves. We suggest that children employ a different thermoregulatory strategy. In extreme temperatures, they may indeed be more vulnerable, but under most ambient conditions they are not necessarily inferior to adults. Children rely more on dry heat dissipation by their larger relative skin surface area than on evaporative heat loss. This also enables them to evaporate sweat more efficiently with the added bonus of conserving water better than adults.
这篇综述重新审视了一些与体温调节相关的儿童与成人的差异，并对已被接受的解释提出了不同观点。从形态学上讲，儿童的体表面积与质量比更高——这是“干性”散热和有效汗液蒸发的一个主要因素。在运动方面，儿童比成人的效率更低，每单位体重产生的热量更多。此外，在热应激下，儿童需要将更大比例的心输出量分流到皮肤。因此，他们更大比例的心输出量从身体核心和工作肌肉分流——尤其是在炎热条件下。最后，在所有环境条件和异速生长比较下，儿童的出汗率低于成人。这些差异似乎表明儿童在体温调节方面较差，但没有流行病学数据显示儿童的热损伤率更高，即使在热浪期间也是如此。我们认为儿童采用了不同的体温调节策略。在极端温度下，他们可能确实更脆弱，但在大多数环境条件下，他们不一定比成人差。儿童更多地依靠相对较大的皮肤表面积进行干性散热，而不是通过蒸发散热。这也使他们能够更有效地蒸发汗液，并且比成人更能节约用水。
