Failure rate of pulse oximetry in the postanesthesia care unit

The objective of this study was to prospectively examine the incidence of patient-related failure of pulse oximetry in the postanesthesia care unit (PACU).

We studied 2,937 patients who, after receiving anesthesia, were admitted to the PACU at the University of Washington Medical Center from December 1989 through May 1990. Pulse oximetry readings were recorded using a Nellcor N-200 oximeter without electrocardiographic synchronization. Failure was defined as the inability to obtain a pulse oximetry reading for 2 or more 15-minute periods after eliminating probe position or mechanical malfunctions.

The overall failure rate in our study was 0.64%, with 19 patient-related pulse oximetry failures from 2,937 cases. Patients on whom the device failed were significantly older (62 +/- 18 vs 46 +/- 19 yr [mean +/- SD]; p < 0.01), had higher median American Society of Anesthesiologists status (3 vs 2), and had longer operations than nonfailure patients (328 +/- 182 vs 185 +/- 127 min; p < 0.01). There was no difference in the duration of PACU times for both groups.

The failure rate and patient characteristics compare favorably with a previously published study of intraoperative pulse oximetry failure. We conclude that while the pulse oximeter is a reliable instrument for the measurement of blood oxygenation, there is a small but consistent incidence of patient-related failure with this monitoring device in the PACU.