Key result
Acute mountain sickness was associated with a significantly smaller increase in LVOT VTI after a passive leg raise maneuver compared with asymptomatic controls (11.71% vs 18.96%; P<0.01).
Why the study?
Does ultrasonography detect a difference in intravascular volume in individuals with acute mountain sickness compared to asymptomatic trekkers?
Cross-Sectional (n=69)
No
Does ultrasonography detect a difference in intravascular volume in individuals with acute mountain sickness compared to asymptomatic trekkers?
Ultrasonography demonstrates that subjects with acute mountain sickness have a higher intravascular volume (suggesting decreased altitude-related diuresis) compared with asymptomatic individuals.
Field ultrasound volume assessment in AMS needs prospective validation; leaves open whether intravascular differences exist at altitude.
OBJECTIVE: To investigate whether ultrasonography can be used for field volume status assessment and to determine whether a detectable difference in intravascular volume exists in individuals with acute mountain sickness (AMS) compared with those without. METHODS: Study was performed at the Himalayan Rescue Association Clinic in Manang, Nepal, located on the Annapurna trekking circuit at an altitude of 3519 m (11545 feet). A convenience sample was taken from individuals trekking over 5 to 8 days from 760 m (2490 feet) to 3519 m (11,545 feet), comparing asymptomatic trekkers vs those who experienced AMS. Subjects were evaluated for AMS based on the Lake Louise AMS Questionnaire (LLS ≥ 3 indicates AMS). After medical screening examination, both groups (control, n = 51; AMS, n = 18) underwent ultrasonography to obtain measurements of inferior vena cava collapsibility index (IVC CI) and left ventricular outflow tract velocity-time integral (LVOT VTI) before and after a passive leg raise (PLR) maneuver. RESULTS: There was no statistically significant difference between groups regarding change in heart rate before and after PLR, or IVC CI; however, there was a statistically significant greater increase in LVOT VTI after PLR maneuver in control group subjects compared with those with AMS (18.96% control vs 11.71% AMS; P < .01). CONCLUSIONS: Ultrasonography is a useful tool in the assessment of intravascular volume at altitude. In this sample, we found ultrasonographic evidence that subjects with AMS have a higher intravascular volume than asymptomatic individuals. These data support the hypothesis that individuals with AMS have decreased altitude-related diuresis compared with asymptomatic individuals.
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Pitman et al. (2015) conducted a cross-sectional in Acute mountain sickness (n=69). Acute mountain sickness vs. Asymptomatic trekkers was evaluated on Increase in left ventricular outflow tract velocity-time integral (LVOT VTI) after a passive leg raise (PLR) maneuver (p=<.01). Acute mountain sickness was associated with a significantly smaller increase in LVOT VTI after a passive leg raise maneuver compared with asymptomatic controls (11.71% vs 18.96%; P<0.01).
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