模拟不同海拔氦氧潜水和体力负荷对人体心肺功能的影响

Effect of simulated different high altitude helium-oxygen diving and physical load on cardiopulmonary function of divers

目的在模拟不同海拔缺氧暴露及氦氧潜水条件下测定潜水员的相关生理指标，探讨不同海拔潜水及体力负荷对人体心、肺功能的影响。方法4名潜水员在高、低压两用舱内，连续9d分别暴露于模拟平原（海拔50m）和海拔3000．4000、5200m环境中，在平原和3000、4000m各逗留2d，5200m逗留3d。分别在3000、4000m模拟30m潜水，1次／d；在5200m的第1天模拟30m潜水，第2天模拟50m潜水，第3天无潜水活动；潜水时间均为60min。每天上午安静环境下，所有被试者静坐10min后测定心率和每搏输出量。测试结束进行体力负荷运动，被试者静坐在自行车功量计上1min后测安静状态下的心率、动脉血氧饱和度（SaO2）、呼出气末端CO2量；然后进行5min蹬车实验，负荷0．5kg，速度为60r／min，用节拍器控制蹬车节奏，测每分钟末心率、SaO2，连续测5min；蹬车结束后，被试者静坐在自行车上休息，测每分钟末心率、SaO：、呼出气末端CO2量，连续测3min。每天下午进行模拟潜水，在潜水停留期间进行心率测试（平原状态不潜水，但进行对比测试）。心率变化值=负荷第5分钟心率一恢复第3分钟心率；根据心率i利用Astrand．P．0列线图，推算出人体的最大摄氧量（VO2max）。结果（1）在3000、4000m模拟30m潜水时的心率，比3000、4000m暴露安静状态时的心率分别下降了9．6％和6．9％。在5200m模拟30、50m潜水时的心率，比5200m暴露安静状态时的心率分别下降了7．6％和8．0％。各海拔潜水时的心率与在该海拔暴露时安静状态下的心率比均有下降趋势，但差异均无统计学意义（P〉0．05）。在3000m时每搏输出量[（68．1±15．8）m1]比50m安静时[（84．7±22．7）m1]明显下降，差异有统计学意义（P〈0．05）。（2）安静状态下、体力负荷后、恢复期，从平原到5200m，各海拔环境下的心率与平原比显著升高，差异均有统计学意义（P〈0．05或P〈0．01）。4000m与5200m比较，安静状态下、体力负荷后、恢复期，心率变化差异无统计学意义（P〉0．05）。（3）随着海拔的升高，安静状态下、体力负荷后，相邻各高海拔之间SaO2持续下降，差异均有统计学意义（P〈0．05或P〈0．01）。（4）3000、4000、5200lil与平原比，CO2max分别下降了6．2％、19．9％、22．3％。（5）安静状态下，5200m时呼出气末端CO2量与平原比显著减少，差异有统计学意义（P〈0．01）；与平原比，3000、4000、5200in恢复期第3分钟末呼出气末端CO2量显著减少，差异均有统计学意义（P〈0．01）。结论高海拔暴露及氦氧潜水后，人体心肺功能有一定的改善。

Objective To monitor physiological indexes of divers in simulated different high altitude helium-oxygen （heliox） diving, and also to explore the effect of different high-altitude diving and physical load on the cardiopulmonary function of divers. Methods In the dual-purpose hyperbaric-hypobaric chambers, 4 divers were exposed to simulated altitudes of 50 （plain） , 3000, 4000 and 5200 m for a succession of 9 days.The divers stayed at 50, 3000 and 4000 m for 2 days respectively, but at 5200 m they stayed fl）r 3 days. At 3000 and 4000 m, the divers conducted 30 m simulated dives, once a day. On the first day at 5200 in, the divers carried out a 30 m simulated dive, and on the second day a 50 m dive, but on the third day no diving activity was conducted. The duration of diving was all 60 minutes. Heart rate and stroke volume of the divers were detected every morning, after they sat at ease for 10 minutes. Heart rate, arterial oxygen saturation （SaO2 ） and exhaled end CO2 volume were measured after the divers took 1 min rest on the treadmill. Then, the divers had 5-minute treadmill exercise with load of 0.5 kg and speed of 60r/rain. The pace of exercise was measured with a pacemeter, and heart rate and SaO2 at the end of each minute were detected for a succession of 5 minutes. After exercise, the divers sat at ease on the treadmill, and heart rate, SaO2 and exhaled end CO2 volume were recorded at the end of each minute for a succession of 3 minutes. Every afternoon, the divers carried out simulated dives, during which heart rate was monitored. （No diving at the plain, but the physiological indexes was measured, which was used as basic value）. Change value of heart rate was the heart rate at the 5th minute subtracted by the recovery heart rate at the 3rd minute. The maximal oxygen uptake （VOz,,ax ） was thus calculated according to heart rate by using the Astrand P. O nomogram. Results （1） When the simulated 30 m dive was performed at the altitudes of 3 000 and 4 000 m, the heart rates of the divers decreased by 9. 6% and 6.9% respectively, as compared with those of the same＇altitudes without dive. Likewise, when the simulated 30 and 50 m dives were conducted at the altitude of 5200 m, the divers＇ heart rates decreased by 7.6% and 8.0% respectively, as compared with those of the same altitude without dive.Heart rates at various high altitudes during the dives tended to decrease, when they were compared with those at the same high altitudes without dives, and statistical significance could be noted, when comparisons were made between them （P 〉0.05）. The stroke volume at 3 000 m [ （68.1 ＋ 15.8） ml] was significantly lower than that at 50 m [ （ 84.72 _ 22.7 ） ml I, with statistical significance （ P 〈 0.05 ）. （2） Heart rates at various high altitudes were significantly higher than that at the plain （50 m）, no matter whether the divers were at rest, with physical load or during the stage of recovery, also with statistical significance （ P 〈 0.05 or P 〈 0.01 ）. No statistical significance could be noted in changes of heart rates, when heart rates of the divers at 4 000 m were compared with those at 5 000 m （ P 〉 0.05 ）. （ 3 ） With the elevation of altitudes, SaO2 levels at different altitudes decreased progressively, and statistical significance could be seen when comparisons were made between thenl（P〈O.05 orP〈O. O1）. （4） VO2 at 3000, 4000 and 5200 m decreased by 6.2%, 19.9% and 22.3% respectively, when compared with that at the plain. （5） When the divers were at rest, CO2 level in the exhaled end-tidal air at 5200 m decreased significantly than that at the plain, with statistical significance （P 〈0.01 ）. When compared with that at the plain, CO2 levels in the exhaled end-tidal air at the end of 3 minutes during recovery at 3000, 4000 and 5200 m decreased significantly, also with statistical significance （P 〈 O. O1 ）. Conclusions Following simulated helium-oxygen diving at high altitudes, the cardiopulmonary function of the divers improved to a certain extent, with the tendency of turning for the better.