Hess Hayden W, Wheelock Courtney E, St James Erika, Stooks Jocelyn L, Clemency Brian M, Hostler David
University at Buffalo, Department of Exercise and Nutrition Sciences, Center for Research and Education in Special Environments, Buffalo, New York U.S.
University at Buffalo, Department of Emergency Medicine, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York U.S.
Undersea Hyperb Med. 2021 Fourth Quarter;48(4):469-476.
Exposure to a reduction in ambient pressure such as in high-altitude climbing, flying in aircrafts, and decompression from underwater diving results in circulating vascular gas bubbles (i.e., venous gas emboli [VGE]). Incidence and severity of VGE, in part, can objectively quantify decompression stress and risk of decompression sickness (DCS) which is typically mitigated by adherence to decompression schedules. However, dives conducted at altitude challenge recommendations for decompression schedules which are limited to exposures of 10,000 feet in the U.S. Navy Diving Manual (Rev. 7). Therefore, in an ancillary analysis within a larger study, we assessed the evolution of VGE for two hours post-dive using echocardiography following simulated altitude dives at 12,000 feet. Ten divers completed two dives to 66 fsw (equivalent to 110 fsw at sea level by the Cross correction method) for 30 minutes in a hyperbaric chamber. All dives were completed following a 60-minute exposure at 12,000 feet. Following the dive, the chamber was decompressed back to altitude for two hours. Echocardiograph measurements were performed every 20 minutes post-dive. Bubbles were counted and graded using the Germonpré and Eftedal and Brubakk method, respectively. No diver presented with symptoms of DCS following the dive or two hours post-dive at altitude. Despite inter- and intra-diver variability of VGE grade following the dives, the majority (11/20 dives) presented a peak VGE Grade 0, three VGE Grade 1, one VGE Grade 2, four VGE Grade 3, and one VGE Grade 4. Using the Cross correction method for a 66-fsw dive at 12,000 feet of altitude resulted in a relatively low decompression stress and no cases of DCS.
暴露于环境压力降低的情况，如在高海拔攀登、乘坐飞机飞行以及从水下潜水减压时，会导致循环血管气泡（即静脉气体栓子[VGE]）。VGE的发生率和严重程度在一定程度上可以客观地量化减压应激和减压病（DCS）的风险，而遵循减压时间表通常可减轻这种风险。然而，在高海拔进行的潜水对减压时间表的建议提出了挑战，美国海军潜水手册（第7版）中减压时间表的建议仅限于10,000英尺的暴露高度。因此，在一项更大规模研究的辅助分析中，我们在模拟12,000英尺的高海拔潜水后，使用超声心动图评估潜水后两小时内VGE的演变情况。十名潜水员在高压舱内进行了两次下潜至66英尺海水深度（通过交叉校正法相当于海平面110英尺海水深度）的潜水，每次潜水30分钟。所有潜水均在12,000英尺高度暴露60分钟后完成。潜水后，将舱内压力减压回到该高度并持续两小时。潜水后每20分钟进行一次超声心动图测量。分别使用Germonpré法和Eftedal及Brubakk法对气泡进行计数和分级。潜水后及在高海拔潜水后两小时内，没有潜水员出现DCS症状。尽管潜水后VGE分级在潜水员之间和潜水员自身存在差异，但大多数（20次潜水中的11次）呈现VGE峰值为0级，3次为1级，1次为2级，4次为3级，1次为4级。在12,000英尺高度进行66英尺海水深度潜水时，使用交叉校正法导致减压应激相对较低，且无DCS病例。
