Cardiopulmonary function in high altitude residents of Ladakh

Wood, Steve; Tsering Norboo; Miles Lilly; Ken Yoneda; Marlowe Eldridge. Cardiopulmonary function in high altitude residents of Ladakh. High Alt. Med. Biol. 4:445-454, 2003. We studied residents of high altitude in Ladakh, India, to determine the effects of altitude, age, gender, and ethnicity on gas exchange and pulmonary function. Physical examinations, including pulse oximetry, hemoglobin concentration, end-tidal P-CO2, and pulmonary function, were conducted on resting Ladakhi and Tibetan subjects at altitudes of 3300, 4200, and 4500 In. A total of 574 men and women, ranging in age from 17 to 82, were studied. At 3300 In, Ladakhis had higher heart rates than Tibetans in both genders and higher P-ETCO2 in women. Above 4000 m, 21 of the 141 men studied (15%) had Hb concentrations higher than 20 g/dL, with one confirmed case of Monge's disease. There was no gender difference in Sa(O2) at any altitude except for pregnant women. At 4600 m, Tibetans had significantly higher peak flows and lower P-ETCO2 than Ladakhis. Ladakhi men had higher diastolic BP than women (91 vs. 81), with no difference in systolic BP. There was no gender difference in BP for Tibetans. An important spirometry finding for both groups was high air flows, with mid-maximal expiratory flow (MMEF) at 130% to 150% of predicted values, compared with 85% for sojourner controls, and FEV1/FVC at 115%, compared with sojourner controls at 98%. Improved lung mechanics may be an important adaptation to the lifelong sustained increase in resting ventilation as well as to indoor biomass smoke and outdoor dust exposure of these populations at high altitude.