Gemae Mohamed R, Akerman Ashley P, McGarr Gregory W, Meade Robert D, Notley Sean R, Schmidt Madison D, Rutherford Maura M, Kenny Glen P
Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada.
Exp Physiol. 2021 Mar;106(3):634-652. doi: 10.1113/EP089073. Epub 2020 Dec 18.
Laser-Doppler flowmetry (LDF) is commonly used to assess cutaneous vasodilatation responses, but its reliability (i.e. consistency) during whole-body passive heating is unknown. We therefore assessed the reliability of LDF-derived indices of cutaneous vasodilatation during incremental whole-body heating. Fourteen young men (age: 24 (SD 5) years) completed three identical trials, each separated by 1 week. During each trial, a water-perfused suit was used to raise and clamp oesophageal temperature at 0.6°C (low-heat strain; LHS) and 1.2°C (moderate-heat strain; MHS) above baseline. LDF-derived skin blood flow (SkBF) was measured at three dorsal mid-forearm sites, with local skin temperature clamped at 34°C. Data were expressed as absolute cutaneous vascular conductance (CVC ; SkBF/mean arterial pressure) and normalised to maximal conductance (%CVC ) achieved via simultaneous local skin heating to 44°C and increasing oesophageal temperature to 1.8°C above baseline. Between-day reliability was characterised as measurement consistency across trials, while within-day reliability was characterised as measurement consistency across adjacent skin sites during each trial. Between- and within-day absolute reliability (coefficient of variation) generally improved with increasing heat strain, changing from poor (>25%) at baseline, poor-to-moderate (15-34%) at LHS, and moderate (10-25%) at MHS. Generally, these estimates were more consistent when expressed as %CVC . Conversely, relative reliability was mostly acceptable (intraclass correlation coefficient ≥0.70) during LHS and when data were expressed as CVC . These findings indicate that the consistency of LDF-derived CVC estimates during heat stress depends on the level of heat strain and method of data expression, which should be considered when designing and interpreting experiments.
激光多普勒血流仪（LDF）常用于评估皮肤血管舒张反应，但其在全身被动加热过程中的可靠性（即一致性）尚不清楚。因此，我们评估了在全身递增加热过程中，LDF得出的皮肤血管舒张指标的可靠性。14名年轻男性（年龄：24（标准差5）岁）完成了三项相同的试验，每次试验间隔1周。在每次试验中，使用水灌注服将食管温度升高并维持在比基线高0.6°C（低热应激；LHS）和1.2°C（中度热应激；MHS）。在三个前臂背侧中部位置测量LDF得出的皮肤血流量（SkBF），并将局部皮肤温度维持在34°C。数据以绝对皮肤血管传导率（CVC；SkBF/平均动脉压）表示，并通过同时将局部皮肤加热至44°C以及将食管温度升高至比基线高1.8°C来实现最大传导率（%CVC）归一化。日间可靠性以各试验间的测量一致性来表征，而日内可靠性以每次试验中相邻皮肤部位间的测量一致性来表征。日间和日内绝对可靠性（变异系数）通常随着热应激增加而提高，从基线时的较差（>25%）、LHS时的差至中等（15 - 34%），变为MHS时的中等（10 - 25%）。一般来说，当以%CVC表示时，这些估计更为一致。相反，在LHS期间以及当数据以CVC表示时，相对可靠性大多是可接受的（组内相关系数≥0.70）。这些发现表明，热应激期间LDF得出的CVC估计的一致性取决于热应激水平和数据表达方法，在设计和解释实验时应予以考虑。
