Arterial oxygen saturation in anaesthetised patients during transfer from induction room to operating room

There is no published study that examines oxygenation of anaesthetised patients during transport from anaesthesia induction room to operating room. Arterial oxygen saturation (SaO2) was measured in twenty-five anaesthetised patients before and during transfer to an adjacent operating room and continuously recorded on a calibrated chart recorder. A telemetry ECG recorder was used to detect cardiac dysrhythmias. All anaesthetists followed their usual anaesthetic practice. Patients ventilated via face-mask and via endotracheal tube were studied. During transfer patients were either apnoeic (n = 8) or breathing room air spontaneously (n = 17). Mean SaO2 before induction was 95.4 (SD 2.5)%, was higher after induction of anaesthesia, 98.5 (SD 1.4)% and fell after transfer, 95.7 (SD 2.6)%. A fall in SaO2 was recorded for 21 patients. No SaO2 value below 90% was seen. The decrease in SaO2 was related to the time taken to transfer the patients and spontaneous ventilation (Multiple regression analysis); it was not related to the body mass index although two of the greatest decreases were seen in obese patients. Transfer time averaged 51 seconds (range: 24-97 s). No changes in cardiac rhythm were seen. Transfer of anaesthetised patients was accompanied by variable falls in SaO2 which related to duration of transfer and spontaneous breathing of room air and which were not associated with new dysrhythmias.