Pulse oximetry for perioperative monitoring.

Background: Monitoring with pulse oximetry might improve patient outcome by enabling an early diagnosis and consequently, correction of perioperative events that might cause postoperative complications or even death. Only a few randomized clinical trials of pulse oximetry have been performed during anaesthesia, and in the recovery room which describe perioperative hypoxaemic events, postoperative cardiopulmonary complications and cognitive dysfunction.
Objectives: The objective of this review was to assess the effect of perioperative monitoring with pulse oximetry and to clearly identify the adverse outcomes that might be prevented or improved by the use of pulse oximetry.
Search Strategy: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2003, issue 1) MEDLINE (1966 to January 2003), EMBASE (1980 to January 2003), and by checking the reference lists of trials and review articles.
Selection Criteria: All controlled trials that randomized patients to either pulse oximetry or no pulse oximetry during the perioperative period, including the operating and recovery room.
Data Collection and Analysis: Two reviewers independently assessed data in relation to events detectable by pulse oximetry, any serious complications that occurred during anaesthesia or in the postoperative period, intra- or postoperative mortality, and duration of recovery or intensive care stay. Formal statistical synthesis of individual trials was not performed in view of the variety of outcomes studied.
Main Results: Searching identified six reports. Four studies with data from a total of 21,773 patients were considered eligible for analysis. Only two studies specifically addressed the outcomes in question, both found no evidence of an effect on the rate of postoperative complications using perioperative pulse oximetry. Two studies used hypoxaemia detectable by pulse oximetry to assess the value of perioperative monitoring, although outcomes were not given. It was found that hypoxaemia was reduced in the pulse oximetry group both in the operating theatre and in the recovery room. During observation in the recovery room, the incidence of hypoxaemia in the pulse oximetry group was 1.5-3 times less. The postoperative cognitive function using the Wechsler memory scale and continuous reaction time was independent of perioperative monitoring with pulse oximetry. The other study showed that postoperative complications occurred in 10% of the patients in the oximetry group and in 9.4% in the control group. No statistically significant differences were detected in cardiovascular, respiratory, neurologic, or infectious complications in the two groups. The duration of hospital stay was a median of five days in both groups, and an equal number of in-hospital deaths was registered in the two groups.
Reviewer's Conclusions: The studies confirmed that pulse oximetry can detect hypoxaemia and related events. However, we have found no evidence that pulse oximetry affects the outcome of anaesthesia. The conflicting subjective and objective results of the studies, despite an intense, methodical collection of data from a relatively large population, indicate that the value of perioperative monitoring with pulse oximetry is questionable in relation to improved reliable outcomes, effectiveness and efficiency.