Prophylactic bosentan does not improve exercise capacity or lower pulmonary artery systolic pressure at high altitude.

Hypoxic pulmonary vasoconstriction in response to high altitude ascent may contribute to decreased exercise capacity. Endothelin receptor antagonists reduce pulmonary artery pressure and improve exercise capacity in patients with pulmonary arterial hypertension, but their effects on exercise capacity at altitude are unknown. We studied the efficacy of bosentan started 5 days prior to ascent on exercise capacity and pulmonary artery systolic pressure (PASP) at 3800 m altitude. Eight healthy subjects completed a double-blinded, randomized, placebo-controlled, crossover study. The end-points were time to complete a cycle ergometer time trial, PASP, and hemoglobin oxygen saturation (SpO2). The time to complete the time trial at altitude in subjects on placebo and bosentan was 527+/-159 and 525+/-156 s respectively (P=0.90). PASP was not different on bosentan compared with placebo. Mean SpO2 during the altitude time trial was lower in subjects taking bosentan compared to placebo (78+/-6 vs. 85+/-8% respectively, P=0.03). Bosentan initiated 5 days prior to ascent to high altitude did not improve exercise capacity or reduce PASP, and worsened SpO2 during high intensity exercise at altitude.

Severe high altitude pulmonary oedema: a patient managed successfully with non-invasive positive pressure ventilation in the Emergency Department.

High altitude pulmonary oedema (HAPE) is a well-known potential hazard of activities at high altitudes but not a common disease presentation that most emergency physicians have experience treating. The mainstay of treatment is intuitive--early recognition with immediate descent, rest and oxygen--but what does the emergency physician do when a patient is in severe distress from HAPE even after descent to sea level? A case of severe HAPE is presented in a young man; the successful treatment strategy is outlined including non-invasive positive pressure ventilation. The role of calcium antagonists, corticosteroids and phosphodiesterase inhibitors are also discussed in the acute management of this potentially life-threatening condition.