Chronic Intermittent Hypoxia at High Altitude Exposure for over 12 Years: Assessment of Hematological, Cardiovascular, and Renal Effects

Abstract

The aim of this cross-sectional study was to assess the health status of subjects weekly commuting between sea level and 3550-m altitude for at least 12 yr (average 22.1 +/- 5.8). We studied 50 healthy army men (aged 48.7 +/- 2.0) working 4 days in Putre at 3550-m altitude, with 3 days rest at sea level (SL) at Arica, Chile. Blood pressure, heart rate, Sa(O(2) ), and altitude symptoms (AMS score and sleep status) were measured at altitude (days 1, 2, and 4) and at SL (days 1, 2, and 3). Hematological parameters, lipid profile, renal function, and echocardiography were performed at SL on day 1. The results showed signs of acute exposure to hypoxia (tachycardia, high blood pressure, low Sa(O(2) )), AMS symptoms, and sleep disturbances on day 1, which rapidly decreased on day 2. In addition, echocardiographic findings showed pulmonary hypertension (PAPm > 25 mmHg, RV and RA enlargement) in 2 subjects (4%), a PAPm > 20 mmHg in 14%, and a right ventricle thickness >40 mm in 12%. Hematocrit (45 +/- 2.7) and hemoglobin (15 +/- 1.0) were elevated, but lower than in permanent residents. There was a remarkably high triglyceride level (238 +/- 162) and a mild decrease of glomerular filtration rate (34% under 90 mL/min and 8% under 80 mL/min of creatinine clearance). In conclusion, in these preliminary results, in chronic intermittent hypoxia exposure even over longer periods, most subjects still show symptoms of acute altitude illnesses, but a faster recovery. Findings in triglycerides, in the pulmonary circulation and in renal function, are also a matter of concern.

Moderately high altitude habitation modulates lipid profile and alkaline phosphatase activity in aged Khasis of Meghalaya

“…Increased physical activity from walking on rugged terrains under conditions of mild hypoxia among the hill residents of Shillong could explain these findings, which is supported by the observation of Baibas et al (23). Another report (24) from study on inhabitants of high altitude populations of Peru showed no differences in total cholesterol level, whereas, the triglyceride level was markedly elevated in comparison to low altitude, which is also corroborated by other findings (25). Furthermore, the higher activity of serum ALP in O S with respect to O B may perhaps be due to high bone and/or intestinal turnover in high altitude O S population leading to increased ALP release into the plasma.…”

Do People Live at Sea Level and the Dead Sea Level Have Different Patterns of Anti-Hypertensive Drugs

“…Actually, these findings are not consistent with other studies which showed increased blood pressure variables with altitude (Wolfel et al, 1985;Brito et al, 2007). It seems that the altitude difference was not enough to exert hypoxic effect which is reflected by having no significant difference in the mean of PCV in study areas.…”

“…Living at altitude areas is expected to lead to hypoxia and is considered as a risk factor for developing hypertension (Wolfel et al, 1985;Brito et al, 2007). According to the study of Luks (2007), no clear mechanisms explaining the increased blood pressure at high altitudes and further, guidelines or patient-centered strategies to control patients with hypertension at high altitudes are not well accepted.…”

Acclimatization to chronic intermittent hypoxia in mine workers: a challenge to mountain medicine in Chile

“…The risk of polycythemia was lower than in chronic highlanders (Richalet et al, 2002). In another study of subjects exposed to CIH for 12 years or more to a 4 x 3 commuting system (4 days at altitude and 3 days at sea level) at 3,550 m altitude, hematocrit and hemoglobin reached lower values than for residents at altitude over 4,000 m (Brito et al, 2007).…”

“…Mining workers at high altitudes must adjust to the requirements of hypobaric hypoxia for some days and then return to sea level, where they lose some of the acclimatization to hypoxia, depending on the time in normoxia. This model of exposure to hypobaric hypoxia, named the Chilean model or CIH exposure, has received increased attention in recent years Chamorro et al, 1993;Jalil et al, 1994;Jimenez 1995;Richalet et al, 2002;Farias et al, 2006;Brito et al, 2007).…”