Early detection of acute mountain sickness after high-altitude exposure

BACKGROUND Early identification of individuals vulnerable to acute mountain sickness (AMS) is clinically challenging. We hypothesized that exercise stress echocardiography (ESE), conducted shortly after high-altitude arrival, could reveal distinctive right ventricular (RV) and pulmonary vascular responses predictive of AMS development. METHODS Within 6 hours of arrival, 50 healthy lowland residents underwent ESE. Key measures included systolic pulmonary artery pressure (SPAP), pulmonary vascular resistance (PVR), tricuspid annular peak systolic velocity (TV s′), RV fractional area change (FAC), inferior vena cava (IVC) diameter, and mean PAP/cardiac output (CO) slope. AMS was assessed the next morning using the Lake Louise Score. RESULTS Of the participants, 23 (46%) developed AMS and 27 (54%) did not (non-AMS group). At peak exercise, the AMS group exhibited significantly higher SPAP (54.88 ± 7.89 vs. 46.71 ± 8.48 mmHg, p < 0.001) and PVR (2.24 ± 0.26 vs. 2.03 ± 0.17 WU, p = 0.001), accompanied by greater increases from rest (denoted as Δ) in SPAP (20.42 ± 8.13 vs. 13.21 ± 6.22 mmHg, p = 0.015) and PVR (0.40 ± 0.19 vs. 0.30 ± 0.17 WU, p = 0.010). Conversely, the AMS group demonstrated impaired RV contractile reserve, reflected by smaller in ΔTV s′ (0.05 ± 0.04 vs. 0.08 ± 0.03 m/s, p = 0.006) and ΔFAC (8.26 ± 3.89 vs. 12.22 ± 5.35%, p = 0.033). IVC diameter was larger in the AMS group both at rest and during peak exercise (p = 0.047 and p = 0.018). A nomogram incorporating peak IVC diameter, ΔPVR, and ΔTV s′ predicted AMS with an area under the curve (AUC) of 0.865 and an accuracy of 84.0%. CONCLUSION ESE detects early alterations in RV function, IVC dynamics, and pulmonary circulation in individuals susceptible to AMS within hours of high-altitude exposure. A model based on IVC, ΔPVR, and ΔTV s′ offers a practical tool for early AMS risk stratification. Clinical trial number: not applicable