Blood pressure trend of lowlanders during first 6 days of acclimatisation to high altitude

Abstract

The present study was planned to delineate the blood pressure (BP) response of the lowlanders during initial 6 days of acclimatisation to high altitude. 398 normotensive sojourners at sea level ascended to HA (3,500 m). Blood pressure response of these subjects were analysed for 6 consecutive days at HA. Based on the BP response of these subjects on the 6th day at HA they were divided into two groups: HBP-high BP group and NBP- normal BP group. It showed that on 6th day at HA, 51 out of 398 subjects presented with BP≥140/90 mmHg (HBP) while others remained normotensive (NBP). Comparative systolic BP of HBP and NBP groups during successive days at HA were as follows: HA day 1 (146.8 ± 13.7 mmHg vs 146.3 ± 8.8 mmHg, p>0.05), HA day 4 (144.5 ± 8.7 mmHg vs 135.0 ± 7.0 mmHg, p<0.05) and HA day 6 (148.1 ± 7.9 mmHg vs 131.7 ± 5.3 mmHg, p<0.05). Whereas, diastolic BP of HBP and NBP groups were: HA day 1 (94.0 ± 8.1 mmHg vs 93.2 ± 6.6 mmHg, p>0.05), HA day 4 (88.9 ± 6.0 mmHg vs 85.3 ± 5.1 mmHg, p<0.05) and HA day 6 (93.8 ± 6.3 mmHg vs 83.7 ± 3.8 mmHg, p<0.05). It was found that NBP had initially raised BP which returned to normal levels after acclimatisation period of 6 days, but in HBP, it started rising after 4th day. It can be concluded that those individuals whose BP on 6th day at HA does not return to normal after acclimatisation period needs regular follow up as these individuals can have a delayed acclimatisation normalising BP later on or can become hypertensive subsequently.