Objective: To determine the incidence of hypoxaemia and the efficacy of oxygen therapy in the early postoperative period.
Design: Prospective, randomized study.
Setting: Regional hospital.
Patients: 89 patients undergoing general anaesthesia divided into two groups, I (n = 45) and II (n = 44).
Interventions: Patients of group I breathed room air while patients of group II received supplementary oxygen.
Measurements and main results: Oxygenation was monitored continuously for 60 minutes with a pulse oximeter after the end of surgery; hypoxaemia was graded into four values of SpO2: mild (86-90%), moderate (81-85%), severe (76-80%), extreme (< or = 76%). One or more episodes of mild hypoxaemia were recorded in 68% of patients in group I and in 36% of patients in group II (p < 0.005); moderate hypoxaemia were recorded in 51% of patients in group I compared with 13% of patients in group II (p < 0.001). Episodes of severe or extreme hypoxaemia were recorded in 22% and in 6% of patients in group I; no patients in group II exhibited such small values of saturation. The smallest recorded SpO2 values were 81 +/- 5.94% in group I and 89 +/- 8.63% in group II (p < 0.001).
Conclusions: There is a high incidence of clinically unsuspected hypoxaemia in the early postoperative period, the use of supplemental oxygen reduces but does not prevent hypoxaemic episodes, every patient should be monitored continuously with a pulse oximeter in the recovery room.