B-line Prevalence Is Higher with Increases in Altitude but Does Not Correlate with AMS Symptomatology.

IntroductionPulmonary B-lines can be seen on lung ultrasound (LUS) and indicate the presence of pulmonary edema, as is seen in high-altitude pulmonary edema (HAPE). While asymptomatic B-lines have been observed in high-altitude travelers without clinical HAPE, their prevalence and relationship to high-altitude physiology remain poorly understood. This study aims to characterize B-line development in high-altitude travelers and its relationship to physiologic changes.MethodsThis observational study investigated adult trekkers in Nepal's Khumbu Valley. An 8-point LUS was performed to obtain a B-line quantification score. Altitude (2610-5364 m), vital signs, and Lake Louise score (LLS) for acute mountain sickness (AMS) were also recorded. A subset of participants was followed longitudinally as they ascended. Regression analyses were performed to compare the B-line score with altitude, pulse oximetry (SpO2), and LLS.ResultsA total of 88 subjects were enrolled, and 21 of these were followed longitudinally. There was a significant positive correlation between altitude and B-line score (r = 0.18, p = .049) in the general population; however, this finding was not significant in the longitudinal group (r = 0.21, p = 0.13). B-line score was inversely correlated with resting SpO2 (r = -0.3, p = 0.0008). There was no significant relationship between B-line score and LLS (r = 0.14, p = 0.12).ConclusionsLUS B-line scores were higher with increases in altitude, and resting SpO2 decreased with higher B-line scores. B-line scores were not correlated with the development of symptoms of AMS. More research is needed to elucidate the clinical significance of these asymptomatic findings.