Anderson G S, Martin A D
School of Kinesiology, University College of the Fraser Valley, Abbotsford, BC, Canada.
Undersea Hyperb Med. 1994 Dec;21(4):431-41.
Using data compiled by the Brussels Cadaver Analysis Study on 13 unembalmed cadavers, this study examined the validity of assumptions often made concerning the role of the skin and adipose tissue layers in thermal insulation in vivo. Skin thickness was previously reported to vary from 0.35 to 2.55 mm, depending on the site of measurement and gender of the subject. Assuming a thermal conductivity of 0.70 x 10(-3) kcal/(cm.s-1.degree C-1) for the skin, heat flux across the skin would vary between site and gender in the order of 7.5 times, ranging from 0.16 to 1.20 kcal.min-1.degree C-1.m-2. Due to the negligible thermal gradient across the skin layer, however, this would be of little physiologic significance. Assumptions concerning the homogeneity of skin thickness across gender and measurement site when investigating thermal insulation of the peripheral tissues would not, therefore, influence the reported results significantly. However, it has recently been shown that the calculated lipid fraction of the adipose tissue layer varies according to a person's level of adiposity. Using a two-component model of adipose tissue, the predicted thermal conductivity (k) of the adipose tissue in the present sample was found to range from 0.50 to 0.97 x 10(-3) kcal/(cm.s-1.degree C-1), being significantly lower (P = 0.005) in the five most obese cadavers [6.66 +/- 0.45 x 10(-4) kcal/(cm.s-1.degree C-1)] than in the five most lean cadavers [8.22 +/- 0.93 x 10(-4) kcal/(cm.s-1.degree C-1)]. Adiposity level correlated significantly (r = 0.80; P < 0.01) with calculated k values, suggesting caution must be taken when assuming a single k for the adipose tissue layer when examining divergent populations (i.e., obese vs. thin).
本研究使用布鲁塞尔尸体分析研究汇编的13具未防腐尸体的数据，检验了有关皮肤和脂肪组织层在体内隔热作用的常见假设的有效性。先前报道，皮肤厚度在0.35至2.55毫米之间变化，具体取决于测量部位和受试者的性别。假设皮肤的热导率为0.70×10⁻³千卡/（厘米·秒⁻¹·℃⁻¹），则穿过皮肤的热通量在不同部位和性别之间的变化幅度约为7.5倍，范围从0.16至1.20千卡·分钟⁻¹·℃⁻¹·米⁻²。然而，由于穿过皮肤层的热梯度可忽略不计，因此这在生理上意义不大。因此，在研究外周组织隔热时，关于不同性别和测量部位皮肤厚度均匀性的假设不会显著影响报告结果。然而，最近有研究表明，脂肪组织层的计算脂质分数会根据人的肥胖程度而变化。使用脂肪组织的双组分模型，发现本样本中脂肪组织的预测热导率（k）范围为0.50至0.97×10⁻³千卡/（厘米·秒⁻¹·℃⁻¹），在五具最肥胖的尸体中[6.66±0.45×10⁻⁴千卡/（厘米·秒⁻¹·℃⁻¹）]明显低于五具最瘦的尸体[8.22±0.93×10⁻⁴千卡/（厘米·秒⁻¹·℃⁻¹）]（P = 0.005）。肥胖程度与计算得到的k值显著相关（r = 0.80；P < 0.01），这表明在研究不同人群（即肥胖与消瘦人群）时，假设脂肪组织层的单一k值时必须谨慎。
