最大吸气后屏气时间对皮肤交感性缩血管反应的影响

Skin sympathetic vasoconstrictor response to static maximum inspiratory breath-holds： effects of breath-hold duration

目的定量分析最大吸气后静态屏气时间对前臂和小腿皮肤血流的影响。方法选取健康志愿者12例，于最大吸气后进行不同时间长度的静态屏气（随机分为10、20和40s以及尽可能最长时间屏气），采用激光多普勒血流仪连续测量前臂和小腿皮肤血流量，并分别于屏气前、中、后计算皮肤平均血流量，起始潜伏期和恢复潜伏期。结果不同时间长度的静态屏气均可明显降低前臂和小腿皮肤血流量（P〈0．01），而且屏气时间长度对血流量下降幅度、起始潜伏期和恢复潜伏期均无影响（P〉0．05）。屏气时前臂处平均皮肤血流量和血流量最小值明显低于小腿处（P〈0．05）；然而前臂处起始潜伏期（4．41±0．44）8和恢复潜伏期（5．95±0．59）s均明显短于小腿处起始潜伏期（4．83±0．70）s和恢复潜伏期（7．33±0．91）s，且差异有统计学意义（P〈0．05）。结论静态最大吸气后屏气可明显降低皮肤血流量，降低程度与屏气时间长度无关；由屏气激活的前臂处交感性缩血管神经活性高于小腿处。

Objective To quantify the temporal changes in the volume of blood flow to the skin of the forearm and lower leg during static maximum inspiratory breath-holding of different durations. Methods Blood flow to the skin of the forearm and lower leg were continuously measured with laser Doppler flowmetry in 12 healthy subjects. They were randomly selected to hold their breath for 10, 20 or 40 seconds, or as long as possible. The volume of skin blood flow, the onset latency and the recovery latency were measured before, during and after the breath holding. Results Blood flow decreased significantly during each breath-hold with any durations. The magnitude of the de- crease and its latencies were similar with all the durations. The average volume of skin blood flow and it＇s minimum value during each breath-hold were significantly lower in the forearms than in the lower legs. However, the average onset latency （4.41 ＋ 0.44 s） and the average recovery latency （5.95 ＋ O, 59 s） in the forearms were significantly shorter than in the lower legs （4.83 ＋ 0.70 s for onset and 7.33 ＋ 0.91 s for recovery）. Conclusion The volume of skin blood flow decreases during a static maximum inspiratory breath-hold, and the magnitude of the increase is not related to the duration of the breath-hold. The generalized increase in skin sympathetic vasoconstrictor activity during a static breath-hold is greater in the forearm than in the lower leg.