Christensen C C, Ryg M, Refvem O K, Skjønsberg O H
Dept of Pulmonary Medicine, Ulleval Hospital, Oslo, Norway.
Eur Respir J. 2000 Apr;15(4):635-9. doi: 10.1183/09031936.00.15463500.
The arterial oxygen tensions (Pa,02) in chronic obstructive pulmonary disease (COPD) patients travelling by air, should, according to two different guidelines, not be lower than 7.3 kPa (55 mmHg) and 6.7 kPa (50 mmHg), respectively, at a cabin pressure altitude of 2,438 m (8,000 ft). These minimum in-flight Pa,O2 values are claimed to correspond to a minimum Pa,O2 of 9.3 kPa (70 mmHg) at sea-level. The authors have tested whether this limit is a safe criterion for predicting severe in-flight hypoxaemia. The authors measured arterial blood gases at sea-level, at 2,438 m and at 3,048 m (10,000 ft) in an altitude chamber at rest and during light exercise in 15 COPD patients with forced expiratory volume in one second (FEV1) <50% of predicted, and with sea-level Pa,O2 >9.3 kPa. Resting Pa,O2 decreased below 7.3 kPa and 6.7 kPa in 53% and 33% of the patients, respectively, at 2,438 m, and in 86% and 66% of the patients at 3,048 m. During light exercise, Pa,O2 dropped below 6.7 kPa in 86% of the patients at 2,438 m, and in 100% of the patients at 3,048 m. There was no correlation between Pa,O2 at 2,438 m and pre-flight values of Pa,O2, FEV1 or transfer factor of the lung for carbon monoxide. In contrast to current medical guidelines, it has been found that resting arterial oxygen tension >9.3 kPa at sea-level does not exclude development of severe hypoxaemia in chronic obstructive pulmonary disease patients travelling by air. Light exercise, equivalent to slow walking along the aisle, may provoke a pronounced aggravation of the hypoxaemia.
根据两项不同的指南，慢性阻塞性肺疾病（COPD）患者乘坐飞机时，在客舱压力高度为2438米（8000英尺）时，动脉血氧分压（PaO₂）分别不应低于7.3千帕（55毫米汞柱）和6.7千帕（50毫米汞柱）。这些飞行中最低的PaO₂值据称相当于海平面时最低PaO₂为9.3千帕（70毫米汞柱）。作者测试了这一限值是否是预测飞行中严重低氧血症的安全标准。作者在海拔高度舱内，对15例一秒用力呼气量（FEV₁）<预计值50%且海平面PaO₂>9.3千帕的COPD患者，在海平面、2438米和3048米（10000英尺）处，静息状态及轻度运动时测量动脉血气。在2438米处，分别有53%和33%的患者静息PaO₂降至7.3千帕和6.7千帕以下；在3048米处，分别有86%和66%的患者静息PaO₂降至7.3千帕和6.7千帕以下。在轻度运动时，在2438米处，86%的患者PaO₂降至6.7千帕以下；在3048米处，100%的患者PaO₂降至6.7千帕以下。2438米处的PaO₂与飞行前的PaO₂、FEV₁或肺一氧化碳转运因子值之间无相关性。与当前医学指南相反，研究发现海平面静息动脉血氧分压>9.3千帕并不能排除乘坐飞机的COPD患者发生严重低氧血症。相当于在过道缓慢行走的轻度运动可能会使低氧血症明显加重。
