- acute respiratory failure occurring within the seven days of the surgery procedure which is defined as presence and persistence for at least 30 min and at least one of the two followings: 1) a respiratory rate of more than 30 breaths per minute and 2) clinical signs suggestive of respiratory muscle fatigue, increased work of breathing, or both, such as use of respiratory accessory muscles, paradoxical motion of the abdomen, or retraction of intercostal spaces