Pulmonary edema is cause of respiratory failure. If patient does not respond to pharmacological therapy BIPAP or CPAP may be needed. CPAP is began with a positive end expiratory pressure of 5cmH2o and increasing. It works by delivering high flow oxygen to alveoli leading to improving FRC. This opens the alveoli and reducing the work of breathing and causing the fluid to go back into the circulation. This improves the symptoms of dyspnea and apprehension and also the edema.