Thundiyil Josef G, Williams Alex T, Little Ian, Stutsman Margaret, Ladde Jay G, Papa Linda
Orlando Health, Department of Emergency Medicine, United States.
Heliyon. 2023 May 5;9(5):e16000. doi: 10.1016/j.heliyon.2023.e16000. eCollection 2023 May.
It is postulated that lack of hypoxic ventilatory response is a predictor for AMS. End-tidal carbon dioxide (ETCO) is an accurate, noninvasive surrogate measure of ventilation.
We sought to determine if changes in baseline ETCO predicts the development of AMS.
This prospective cohort study took place in three separate high-altitude hiking treks. Subjects included a convenience sample of hikers. Predictor variable was change in ETCO levels and outcome variable was AMS. Measurements of ETCO levels were obtained at the base and repeated daily at various elevations and the summit of each hike. Concurrently, hikers were scored for AMS by a trained investigator. We utilized correlation coefficients and developed a linear regression model for analysis.
21 subjects in 3 separate hikes participated: 10 ascended to 19,341 ft over 7 days, 6 ascended to 8900 ft in 1 day, and 4 ascended to 11,006 ft in 1 day. Mean age was 40 years, 67% were males, mean daily elevation gain was 2150 ft, and 5 hikers developed AMS. The correlation coefficients for ETCO and development of AMS were -0.46 (95%CI -0.33 to -0.57), and -0.77 (95%CI -0.71 to -0.83) for ETCO and altitude. ETCO predicted the development of symptoms better than the elevation with AUCs of 0.90 (95%CI 0.81-0.99) versus 0.64 (95%CI 0.45-0.83). An ETCO measurement of ≤22 mmHg was 100% sensitive and 60% specific for predicting AMS.
ETCO was strongly correlated with altitude and moderately correlated with AMS and it was a better predictor than altitude.
据推测，缺乏低氧通气反应是急性高山病（AMS）的一个预测指标。呼气末二氧化碳（ETCO）是一种准确的、非侵入性的通气替代指标。
我们试图确定基线ETCO的变化是否能预测AMS的发生。
这项前瞻性队列研究在三次不同的高海拔徒步旅行中进行。研究对象为徒步旅行者的便利样本。预测变量是ETCO水平的变化，结果变量是AMS。在每次徒步旅行的起点测量ETCO水平，并在不同海拔高度和山顶每天重复测量。同时，由一名经过培训的研究人员对徒步旅行者的AMS进行评分。我们使用相关系数并建立线性回归模型进行分析。
三次不同徒步旅行中的21名受试者参与研究：10人在7天内上升到19341英尺，6人在1天内上升到8900英尺，4人在1天内上升到11006英尺。平均年龄为40岁，67%为男性，平均每日海拔上升2150英尺，5名徒步旅行者患上了AMS。ETCO与AMS发生的相关系数为-0.46（95%CI -0.33至-0.57），ETCO与海拔高度的相关系数为-0.77（95%CI -0.71至-0.83）。ETCO比海拔高度能更好地预测症状的发生，曲线下面积（AUC）分别为0.90（95%CI 0.81 - 0.99）和0.64（95%CI 0.45 - 0.83）。ETCO测量值≤22 mmHg对预测AMS的敏感性为100%，特异性为60%。
ETCO与海拔高度密切相关，与AMS中度相关，且它是比海拔高度更好的预测指标。
