De-adaptation change in cardiac function of laborers engaged in physical labor at high altitude after returning to lower altitude / 解放军医学杂志

ABSTRACT

Objective To assess the effects of physical labor on cardiac function of laborers at high altitude and changes in cardiac function after returning to lower altitude. Methods According to symptomatic scores on Chinese acute high altitude reaction (AHAR), 96 male officers and soldiers, who rapidly entered high altitude areas (3700m altitude),and engaged in heavy physical work for 50 days, were be scored and graded. Levels of creatine kinase isoenzymes -MB (CK-MB) and lactic dehydrogenase isoenzyme -1 (LDH-1) in the serum, Tei index, left ventricular ejection fraction (LVEF), and left ventricular fractional shortening (LVFS) were measured in the 96 servicemen at the 50th day of residing at high altitude, and the 2nd and 15th day after returning to lower altitude (1500m altitude), and the results were compared with that of 50 healthy controls residing at 1500m. Results Among the 96 male servicemen, 71 developed AHAR, and 24 of them had severe AHAR, 47 mild to moderate AHAR, and the rest 25 had no AHAR. Levels of serum CK-MB, LDH-1 and Tei index were higher in the severe AHAR group than in the mild to moderate AHAR group, higher in the mild to moderate AHAR group than in the no AHAR group and higher in the no AHAR group than in the healthy group. As far as the values of LVEF and LVFS were concerned, the severe AHAR group 0.05). Conclusion Heavy physical work at high altitude could obviously impair human cardiac function. The impairment may aggravate along with increase in severity of AHAR. However, cardiac function may be improved significantly after returning to low altitude for 2 days, and recover to normal status 15 days later.