Effects of Different Inhalation Oxygen Concentrations on Postoperative Atelectasis

Before anesthesia induction, the participants inhaled pure oxygen through the mask for 5 mins. After successful anesthesia induction, Fio2 will be adjusted to 30%, and the total gas flow rate will be set at 2L/min. All patients will be performed via the lung protective ventilation strategy. The respiratory parameters are VT: 6-8ml/kg, PEEP: 6-8 cmh2O, RR: 1:2, and respiratory rate will be adjusted by maintaining a partial pressure of carbon dioxide at 35-45 mmHg. Manual lung recruitment maneuvers will be performed after tracheal intubation and before tracheal extubation, however when intraoperative oxygen saturation is less than 92% the manual lung recruitment maneuver will be done too. Arterial blood will be collected twice for blood gas analysis, the first once is in the non-oxygen inhalation state before anesthesia induction and the second is 30min before the end of surgery. Patients in both groups will be extubated in the operating room and then sent to the PACU.

Before anesthesia induction, the participants inhaled pure oxygen through the mask for 5 mins. After successful anesthesia induction, Fio2 will be adjusted to 60%, and the total gas flow rate will be set at 2L/min. All patients will be performed via the lung protective ventilation strategy. The respiratory parameters are VT: 6-8ml/kg, PEEP: 6-8 cmh2O, RR: 1:2, and respiratory rate will be adjusted by maintaining a partial pressure of carbon dioxide at 35-45 mmHg. Arterial blood will be collected twice for blood gas analysis, the first once is in the non-oxygen inhalation state before anesthesia induction and the second is 30min before the end of surgery. Patients in both groups will be extubated in the operating room and then sent to the PACU.