Effectiveness of positive end-expiratory pressure, decreased fraction of inspired oxygen and vital capacity recruitment maneuver in the prevention of pulmonary atelectasis in patients undergoing general anesthesia: a systematic review.

General anesthesia causes impairment of gas exchange in the lungs that results in decreased oxygenation of the blood; atelectasis is the principle cause of this impaired gas exchange. Anesthesia delivery varies between providers and there is no standard practice to decrease the incidence of postoperative atelectasis.