THE PULSE OXIMETER - APPLICATIONS AND LIMITATIONS - AN ANALYSIS OF 2000 INCIDENT REPORTS

The first 2000 incidents reported to the Australian Incident Monitorin g Study were analysed with respect to the role of the pulse oximeter O f these 184 (9%) were first detected by a pulse oximeter and there wer e a further 177 (9%) in which desaturation was recorded. Of the 1256 i ncidents which occurred in association with general anaesthesia 48% we re ''human detected'' and 52% ''monitor detected'' The pulse oximeter was ranked first and detected 27% of these monitor detected incidents; this figure would have been over 40% if an oximeter had always been u sed and its more informative modulated pulse tone relied upon instead of that of the ''bleep'' of the ECG.-The pulse oximeter is the ''front -line'' monitor for endobronchial intubation, the fourth most common i ncident in association with general anaesthesia (it detected 87% of th e 76 cases in which it was in use). It also played an invaluable role as a ''back-up'' monitor in 40 life-threatening situations in which '' front-line'' monitors (e.g; oxygen analyser, low pressure alarm, capno graph) were either not in use, were being used incorrectly or failed. Other situations detected, in order of frequency of detection, were ci rcuit disconnection, circuit leak, desaturation (severe shunt), oesoph ageal intubation, aspiration and/or regurgitation, pulmonary oedema, e ndotracheal tube obstruction, severe hypotension, failure of oxygen de livery, hypoxic gas mixture, hypoventilation, anaphylaxis, air embolis m, bronchospasm, malignant hyperthermia, and tension pneumothorax. The re were 15 reports of ''failure''; four because the model in use had n o modulated tone or alarm, four in which performance was in fact adequ ate, three were probe problems, two involved ''over-reading'', one ''u nder-reading'' and in one new device the alarm failed. In the theoreti cal analysis of the 1256 general anaesthesia incidents it was conclude d that pulse oximetry, used on its own, would have detected 82% of the se incidents, had they been allowed to evolve (nearly 60% before any p otential for organ damage). It is highly recommended that a suitable p ulse oximeter be used on all patients from the time of arrival in the induction room until return of protective reflexes and demonstration o f adequate saturation when breathing room air.