Blood pressure responses in young adults first exposed to high altitude for 12 months at 3550 m.

To determine the changes in blood pressure (BP) and related variables in sea-level young adults with chronic exposure to high altitude, a longitudinal study was performed in male army recruits (n = 346; age 17.9 +/- 0.1 yr; BMI, 22.5 +/- 0.3 kg/m(2)) first exposed to 3550-m altitude for 12 months. Fifty male recruits (age 17.8 +/- 0.6 and BMI 22.6 +/- 0.3 kg/m(2)) never exposed to altitude were used as controls. A sustained higher mean diastolic BP (DBP) (82.1 +/- 1.0 mmHg at month 3; 81.3 +/- 0.9 mmHg at month 12) was observed, compared to first exposure and the control group (p < 0.001). The BP values were always higher than those of the sea-level control group (systolic blood pressure (SBP) 109 +/- 2.3 and DBP 67.4 +/- 0.8; p < 0.001), and a large proportion of subjects steadily presented overoptimal values for either systolic BP (SBP) (64%) or DBP (77%) and hypertensive DBP values (40%). The higher DBP was associated with lower Sao(2) (OR = 0.919; p < 0.05). In addition, the acute mountain sickness (AMS) score showed a slight decrease during re-exposure (3.9 +/- 0.3 vs.3.4 +/- 0.3; p < 0.001) and an inverse association to the before-descending Sao(2) at month 3 (OR = 0.906, p < 0.01). These data suggest that BP stabilization can take longer than currently thought and that each parameter has a different profile of change. Further, a sustained high DBP should be a matter of epidemiological concern and emphasizes the need for BP monitoring among young lowlanders exposed to high altitude.