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

Objectives: The present study was planned to delineate the blood pressure (BP) response of the lowlanders during initial 6 days of acclimatisation to high altitude. Materials and Methods: 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 6 th day at HA they were divided into two groups: HBP-high BP group and NBP- normal BP group. Results: It showed that on 6 th 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). Conclusion: 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 4 th day. It can be concluded that those individuals whose BP on 6 th 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.