Oxygen saturation in postoperative patients at low risk for hypoxemia: is oxygen therapy needed?

To evaluate the use of oxygen therapy in the immediate postoperative period, 293 postsurgical patients who had not had thoracic, upper abdominal, or neurologic surgery were randomly assigned upon admission to the postanesthesia care unit (PACU) to receive: 1) 4 L unhumidified O2 via nasal cannula, 2) 40% oxygen by face tent, 3) nurse-coached lung hyperinflations, or 4) no oxygen enhancing regimen. Oxygen saturation was measured on all patients at the time of arrival in the PACU, after 15 min, and after 30 min in the PACU. Only 11 patients in all groups (4%) had their O2 saturation decrease to less than 90% during this time. Ten of these had an initial O2 saturation of 92% or less. Significant differences in O2 saturation were found at 15 min and 30 min between Groups 1 and 2 which received O2 compared to Groups 3 and 4 which did not receive supplemental oxygen. The clinical significance of these differences is open to question. Complaints of dryness were most common in those receiving unhumidified oxygen by nasal cannula. Fourteen percent of patients receiving oxygen by face tent found it uncomfortable and complained of nausea. Supplemental oxygen is not essential in maintaining adequate oxygen saturation in these PACU patients when oxygen saturation levels are more than 92% upon admission to the PACU.