Pulse oximetry in the recovery room.

Haemoglobin oxygen saturation (SO2) was measured percutaneously with a pulse oximeter, in a group of 150 healthy ambulant volunteers to determine the range of normal values. The measuring site was not arterialised in advance. SO2 was below 94% in 13.3% of cases, while in no case was it below 90%. SO2 was then measured in 350 patients in the recovery room after a variety of surgical and anaesthetic procedures. Only 1.1% of patients who received additional oxygen following general anaesthesia exhibited an SO2 below 90%, compared to 16.7% of similar cases who did not receive additional oxygen. Administration of additional oxygen raised the SO2 above 90% in all the latter cases. In only 55.3% of those who did not receive additional oxygen was the SO2 above 94%, compared to 86.7% of normal volunteers and 73.9% of patients who received additional oxygen. This study reiterates the need to administer supplemental oxygen to all patients in the recovery room, unless facilities are available to measure SO2. A lower alarm limit of 90% is appropriate for the peri-operative period when using the Criticare Systems 501 oximeter.