[Pulse oximeter. Clinical assessment in the recovery room]

Fifty unselected recovery room patients were monitored using a Nellcor N101 pulse oximeter. Non invasive SaO2 values were compared with simultaneous spectrophotometric measurements made on arterial blood samples (Co-oximeter). Mean pulse oximeter SaO2 was 86.9 +/- 6.08%, with extreme values of 68 and 95.5%. Arterial blood SaO2 was 91.25 +/- 6.28%, with extreme values of 66 and 100%. Linear regression analysis showed a good correlation between the two sets of measures (r = 0.97; p less than 0.005). Twenty one patients had a SaO2 below 90% (mean: 84.83 +/- 5.93%); their measured arterial SaO2 was of 86.14 +/- 6.32%. The correlation between the two sets of low values was good (r = 0.96; p less than 0.05). Pulse oximetry was a non invasive reliable method, but there were some limits to its clinical use. Hypothermia or shock vasoconstriction precluded the measurement of SaO2. Restlessness or shivering were responsible of probe dysfunction and false alarms. False SaO2 readings may result from high levels of carboxyhaemoglobin or dye infusion. Also, each disposable finger probe was reused for a mean of five patients, its cost being relatively high (170 FF, i.e. 28.3 US dollars).