Centro Cardiologico Monzino, IRCCS, Istituto di Cardiologia, Università di Milano, Via Parea 4, 20138 Milan, Italy.
Eur Heart J. 2010 Feb;31(4):457-63. doi: 10.1093/eurheartj/ehp472. Epub 2009 Nov 10.
It is unknown whether subclinical high-altitude pulmonary oedema reduces spontaneously after prolonged altitude exposure. Continuous positive airway pressure (CPAP) removes extravascular lung fluids and improves haemoglobin oxygen saturation in acute cardiogenic oedema. We evaluated the presence of pulmonary extravascular fluid increase by assessing CPAP effects on haemoglobin oxygen saturation under acute and prolonged altitude exposure.
We applied 7 cm H(2)O CPAP for 30 min to healthy individuals after acute (Capanna Margherita, CM, 4559 m, 2 days permanence, and <36 h hike) and prolonged altitude exposure (Mount Everest South Base Camp, MEBC, 5350 m, 10 days permanence, and 9 days hike). At CM, CPAP reduced heart rate and systolic pulmonary artery pressure while haemoglobin oxygen saturation increased from 80% (median), 78-81 (first to third quartiles), to 91%, 84-97 (P < 0.001). After 10 days at MEBC, haemoglobin oxygen saturation spontaneously increased from 77% (74-82) to 86% (82-89) (P < 0.001) while heart rate (from 79, 64-92, to 70, 54-81; P < 0.001) and respiratory rate (from 15, 13-17, to 13, 13-15; P < 0.001) decreased. Under such conditions, these parameters were not influenced by CPAP.
After ascent excessive lung fluids accumulate affecting haemoglobin oxygen saturation and, in these circumstances, CPAP is effective. Acclimatization implies spontaneous haemoglobin oxygen saturation increase and, after prolonged altitude exposure, CPAP is not associated with HbO(2)-sat increase suggesting a reduction in alveolar fluids.
目前尚不清楚亚临床性高原肺水肿在长时间高原暴露后是否会自行消退。持续气道正压通气（CPAP）可除去肺外血管中的液体，并提高急性心源性肺水肿患者的血红蛋白氧饱和度。我们通过评估 CPAP 对急性和长时间高原暴露下血红蛋白氧饱和度的影响，来评估肺外血管液体增加的情况。
我们对急性（Capanna Margherita，CM，海拔 4559 米，停留 2 天，徒步<36 小时）和长时间高原暴露（珠穆朗玛峰南营，MEBC，海拔 5350 米，停留 10 天，徒步 9 天）后的健康个体应用 7cmH2O 的 CPAP 持续 30 分钟。在 CM，CPAP 降低了心率和收缩压肺动脉压，同时血红蛋白氧饱和度从 80%（中位数）、78-81（第一至第三四分位数）升高至 91%、84-97（P<0.001）。在 MEBC 停留 10 天后，血红蛋白氧饱和度从 77%（74-82）自发升高至 86%（82-89）（P<0.001），而心率（从 79、64-92 降至 70、54-81；P<0.001）和呼吸频率（从 15、13-17 降至 13、13-15；P<0.001）降低。在这些情况下，CPAP 并未影响这些参数。
高原上升后，过多的肺液积聚会影响血红蛋白氧饱和度，在这种情况下，CPAP 是有效的。适应意味着血红蛋白氧饱和度的自发升高，并且在长时间高原暴露后，CPAP 与 HbO2-sat 升高无关，这表明肺泡液减少。
