The Australian Incident Monitoring Study. The capnograph: applications and limitations--an analysis of 2000 incident reports

Abstract

The first 2000 incidents reported to the Australian Incident Monitoring Study were analysed with respect to the role of the capnograph. One hundred and fifty-seven (8%) were first detected by a capnograph and there were a further 18 (1%) in which capnography was contributory. Of the 1256 incidents which occurred in association with general anaesthesia 48% were "human detected" and 52% "monitor detected". The capnograph was ranked second and detected 24% of these monitor detected incidents; this figure would have been nearly 30% if a correctly checked, calibrated capnograph had always been used. The capnograph is a "front-line" monitor for oesophageal intubation, failure of ventilation, anaesthetic circuit faults, gas embolism, sudden circulatory collapse and malignant hyperthermia. It is a valuable "back-up" monitor when other monitors (e.g. low pressure alarm, pulse oximeter) are not in use, are being used incorrectly or fail. Such situations, in order of frequency of detection were: circuit-leak, overpressure of the breathing circuit, bronchospasm, leak of ventilator-driving-gas into the patient circuit, aspiration and/or regurgitation and hypoventilation. There were 20 reports of "failure", over two-thirds of which would not have occurred with appropriate checking and calibration. Seven were due to gas sampling problems and 6 to apnoea alarm failure. Two circuit leaks and 2 faulty unidirectional valves were not detected; on 3 occasions problems occurred due to power failure, calibration problems, or misinterpretation of an alarm.(ABSTRACT TRUNCATED AT 250 WORDS)