Changes in blood pressure, oxygen saturation, hemoglobin concentration, and heart rate among low-altitude migrants living at high altitude (5380 m) for 360 days.

Abstract

This article aimed to study the adjustment and adaptation of resting systolic blood pressure (SBP), diastolic blood pressure (DPB), oxygen saturation (SpO2 ), hemoglobin concentration ([Hb]), and heart rate (HR) in low-altitude migrants during a 1-year stay at high altitude. Our study enrolled 35 young migrants who were exposed to a hypoxia environment at 5380 m altitude on the Qinghai Tibetan Plateau between June 21, 2017, and June 16, 2018. We set 14-time points (the 1st-10th, 20th, 30th, 180th, and 360th day after arriving at 5380 m) for obtaining the measurements of resting SBP, DBP, HR, SpO2, and [Hb] and compared them with the control values recorded prior to migration. Variables with continuous data were summarized as means (SD). One-way repeated measures ANOVA without assuming sphericity was carried out to test whether the mean values (SBP, DBP, HR, SpO2 , and [Hb]) on different days were different significantly. Furthermore, Dunnett's multiple comparisons test was carried out to determine the time points whose values were significantly different from the control values. SBP and DBP were continually increasing within d1-3 and peaked on the 3rd day, then steadily declined from d3 to d30. SBP fell back to the control values on d10 (p > 0.05), and DBP fell back to the control values on d20 (p > 0.05). A significant decline occurred on d180 (p < 0.05). Both SBP and DBP were lower than the control values on d180 (p < 0.05), and this trend was maintained to d360. There were similar characteristics of HR and BP in the time course at HA. HR on d1-3 was increasing (p < 0.05) compared to the control values, after which it fell back to the control values on d180 (p > 0.05), and this trend was maintained to d360. SpO2 was the lowest on d1 and lower than the control value throughout the study at HA (p < 0.05). [Hb] increased after long-term exposure (180 and 360 days) to HA (p < 0.05). Our study continuously monitored lowlanders at 5380 m in Tibet, and is perhaps the only longitudinal study of migrants conducted at an altitude above 5000 m during a 1-year period. Our study provides new information on the adjustment and adaptation of [Hb], SpO2 , SBP, DBP, and HR in high-altitude plateau migrants during a 360-day stay at an altitude of 5380 m.