Treatment of HAPE 4.3.1. Bed Rest. Physical activity may lead to contraction of pulmonary vessels resulting in an increase in pulmonary artery pressure and a decrease in arterial partial pressure of oxygen. Therefore, absolute bed rest can reduce muscular activity and contraction of blood vessels and, thus, provide stable pulmonary artery pressure. In some studies [12] , bed rest alone was used for the treatment of mild HAPE.