Patients with OSA may have an increased sensitivity to anesthetics or opioids, greater upper airway collapsibility, and increased risk of postoperative complications. For surgical patients with OSA, supplemental oxygen may be more acceptable than CPAP therapy but three clinical concerns exist. First, hypoxemia may play a critical role in respiratory arousal in surgical patients with OSA. When supplemental oxygen abolishes hypoxemia, the apnea duration may increase, causing hypoventilation as evidenced by hypercarbia, leading to possible life-threatening respiratory depression. Second, postoperative opioids may depress respiration centrally and impair the arousal threshold causing arousal failure, possibly leading to sporadic case of death. The third concern is that supplemental oxygen may mask the ability of oximetry to detect abnormalities in the level of ventilation.
The authors set out to was to investigate the effect of postoperative supplemental oxygen on Sao2, sleep respiratory events, and CO2 level in patients with untreated OSA.
Postoperative supplemental oxygen improved oxygenation in surgical patients with OSA. Supplemental oxygen decreased AHI, hypopnea index, and central apnea index and shortened the longest apnea-hypopnea event duration. Although no overall difference was found between groups in PtcCO2 level, a significant increase of PtcCO2 was found in 11.4% of patients, especially those receiving oxygen on postoperative night 1. Postoperative supplemental oxygen could be used as an alternative therapy for patients with OSA not adherent to CPAP, newly diagnosed patients without adequate time to initiate CPAP therapy, or patients with suspected OSA. Additional monitoring of respiratory rate or PtcCO2, especially on postoperative night 1, is recommended. Further work is needed to identify OSA phenotypes which would benefit from postoperative supplemental oxygen and to identify which patients should be monitored for hypoventilation with respiratory rate or PtcCO2.