Physiological Responses and Evaluation of Effects of BMI, Smoking and Drinking in High Altitude Acclimatization: A Cohort Study in Chinese Han Young Males

Qian-Qian Peng,Quzhen Gesang,Li Jin,Ji Qian,Qu Suo,Duoji Xiao,Zhuoma Basang,Zong La,Zhen Dan,Xiao-Feng Wang,Chao-Ying Cui,Lei Li,Yang De,Ni Qu,La Yang,Puchi Dawa,Christos A Ouzounis

doi:10.1371/journal.pone.0079346

Abstract

High altitude acclimatization is a series of physiological responses taking places when subjects go to altitude. Many factors could influence these processes, such as altitude, ascending speed and individual characteristics. In this study, based on a repeated measurement design of three sequential measurements at baseline, acute phase and chronic phase, we evaluated the effect of BMI, smoking and drinking on a number of physiological responses in high altitude acclimatization by using mixed model and partial least square path model on a sample of 755 Han Chinese young males. We found that subjects with higher BMI responses were reluctant to hypoxia. The effect of smoking was not significant at acute phase. But at chronic phase, red blood cell volume increased less while respiratory function increased more for smoking subjects compared with nonsmokers. For drinking subjects, red blood cell volume increased less than nondrinkers at both acute and chronic phases, while blood pressures increased more than nondrinkers at acute phase and respiratory function, red blood cell volume and oxygen saturation increased more than nondrinkers at chronic phase. The heavy and long-term effect of smoking, drinking and other factors in high altitude acclimatization needed to be further studied.

Highlights

High altitude acclimatization is a series of physiological processes which takes place when subjects go to altitude [1,2]
We extracted 6 composite phenotypes from the physiological traits collected in this study, which were blood pressure changes extracted from manifest variables systolic blood pressures (SBP) and diastolic blood pressures (DBP), respiratory function changes extracted from FEV and FVC, blood cells counts changes extracted from WBC, RBC, HGB, HCT, lymphocyte count (LYM) and neutrophil count (NEUT), red blood cell volume changes extracted from MCV, RDWSD and RDWCV, relative hemoglobin changes extracted from MCH and MCHC and oxygen saturation
We further evaluated the effect of body mass index (BMI), smoking and drinking on extracted composite phenotypes at acute phase and chronic phase through Partial Least Square Path Model (PLSPM) considering altitude of native place as a confounding factor

Summary

Introduction

High altitude acclimatization is a series of physiological processes which takes place when subjects go to altitude [1,2]. At 12,000 feet (3,658 meters), the barometric pressure is only 483 mmHg, so there are roughly 40% fewer oxygen molecules per breath [3]. It lowers the oxygen supply to body tissues [4]. The body must adjust to having less oxygen, for which a series of physiological responses take place, including ventilation function, cardiac function, oxygen delivery function, hematology, muscle structure and metabolism, oxygen consumption and so on [5]. The tissues of the body gradually adjusted themselves to defend against the fall in oxygen partial pressure and mitigate its effect to a remarkable degree

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