Cardiovascular Response to High Altitude Hypoxia

Abstract. Normal and abnormal cardiovascular response to high altitude (HA) hypoxia were studied in 98 healthy subjects and in 15 patients with HA pul-monary oedema (HAPO) and acute mountain sickness (AMS) at an altitude of 3,658 m. The healthy sea level (SL) residents showed marked blood volume changes during the first week with pulmonary hypotension and depression of left ventricular (LV) performance and physical work capacity (PWC). The HA natives, however, had better LV performance and PWC indicating a better adaptation to HA hypoxia. HAPO subjects showed evidence of severe pulmonary hypertension with normal left atrial prescures but the exact mechanism of this condition is still not clear. AMS subjects showed no circulatory abnormalities ' but had relative hypercapnia and severe hypoxemia suggesting that AMS may becauscd by relative hyposensitiveness of the respiratory centre to hypoxia or hypercapnia. 1