Background: Travelling to high altitude (HA) presents a risk of the high levels of pulmonary artery pressure (PAP) at altitude, which is associated with impaired exercise capacity and fatal HA pulmonary oedema. However, prediction of high levels of PAP at altitude is still unclear.

Methods: Echocardiography and pulmonary function tests were performed on 121 healthy men at low altitude (LA) and 4100 m (5 ± 2 h after a 7 day ascent).

Results: HA exposure increased the levels of FEV1/FVC ratio, FEF_{25%, 50%, 75%}, MMEF, mPAP, total pulmonary vascular resistance (PVR) and systolic pulmonary arterial pressure (SPAP). More smokers and lower forced expiratory flow at 25% of forced vital capacity (FEF_25%) at LA were observed in subjects with mPAP≥30 mmHg than those with mPAP<30 mmHg at HA. Multivariate logistic regression identified that FEF_25% at LA [odds ratio (OR) 0.50, 95%CI 0.33−0.76, p = 0.001] and smoking (OR 3.09, 95%CI 1.31–7.27, p = 0.010) were the independent predictors for identifying subjects with mPAP≥30 mmHg at HA. Moreover, FEF_25% at LA was linearly correlated with mPAP at HA (r = -0.31, p < 0.001), which mainly existed in smokers. Compared to subjects with FEF_25% ≥7.55 L/sec at LA, those with FEF_25% <7.55 L/sec at LA showed higher levels of mPAP, and total PVR, and a multivariable OR of 11.16 (95%CI, 3.48–35.81) for developing mPAP ≥ 30 mmHg at HA. However, there was no significant difference in the incidences of AMS and its related clinical symptoms in subjects with different levels of FEF_25%.

Conclusions: Thus, these findings suggest that subjects with low FEF_25% values at LA are susceptible to high levels of PAP at altitude but not the incidence of AMS following short-term HA exposure, especially in smokers.

背景：前往高海拔 (HA) 存在高海拔肺动脉压 (PAP) 水平升高的风险，这与运动能力受损和致命的 HA 肺水肿有关。然而，对高海拔 PAP 水平的预测仍不清楚。

方法：在低海拔 (LA) 和 4100 m（上升 7 天后 5 ± 2 小时）对 121 名健康男性进行超声心动图和肺功能测试。

结果：HA暴露增加了FEV1/FVC比值、FEF _{25%、50%、75%}、MMEF、mPAP、总肺血管阻力（PVR）和收缩期肺动脉压（SPAP）的水平。与 HA 时 mPAP<30 mmHg 的受试者相比，在 LA 时观察到 mPAP ≥ 30 mmHg 的受试者在 LA用力肺活量 (FEF _25% ) 的25% 时吸烟者更多且用力呼气流量更低。多变量逻辑回归确定洛杉矶的FEF _25% [优势比 (OR) 0.50, 95%CI 0.33−0.76, p = 0.001] 和吸烟 (OR 3.09, 95%CI 1.31–7.27, p = 0.010) 是独立预测因子用于识别 HA 时 mPAP≥30 mmHg 的受试者。此外，LA 的FEF _25%与 HA 的 mPAP 呈线性相关（r = -0.31，p< 0.001)，主要存在于吸烟者中。与洛杉矶FEF _25% ≥ 7.55 L/sec 的受试者相比，LA FEF _25% <7.55 L/sec 的受试者的 mPAP 和总 PVR 水平更高，多变量 OR 为 11.16（95%CI，3.48– 35.81) 用于在 HA 发展 mPAP ≥ 30 mmHg。然而，不同FEF _25%水平的受试者的AMS 发生率及其相关临床症状的发生率无显着差异。

结论：因此，这些发现表明，在 LA具有低 FEF _25%值的受试者在海拔高度易受高水平 PAP 的影响，但在短期 HA 暴露后对 AMS 的发生率不敏感，尤其是在吸烟者中。