RESUMO
OBJECTIVE: The Lightman is intended to test the optical and electrical properties of a pulse oximeter probe including the wavelength of the light emitting diode by means of a micro spectrometer. The aim of this study was to evaluate the ability of the Lightman to detect faulty pulse oximeter finger probes by testing the accuracy of the wavelength of the light emitting diode in isolation from the monitor. METHODS: The pulse oximeter measurements of arterial oxygen saturation from the "accurate" and "inaccurate" probes, as identified by the Lightman, were compared with arterial saturation determined by a co-oximeter. Data was analysed from 63 sets of measurements. In addition, we conducted a national survey to determine the testing procedures used by the Biomedical Engineering departments to evaluate the accuracy of pulse oximeter devices. RESULTS: The bias [95% limits of agreement] for accurate, over-reading and under-reading probes were 0.17% [3.6 to -3.3], 1.44% [5.4 to -2.5] and -1.6% [2.6 to -5.8] respectively. The response rate to the national survey was 75% (142/189); a pulse oximeter tester was used by 93/142 (65%) trusts. CONCLUSIONS: Our findings suggest that the Lightman can detect faulty probes and predict reasonably accurately the direction of the probe's error. The Lightman may be considered as a useful tool to assess the accuracy of pulse oximeters. The national survey highlighted a wide variation in the testing procedure utilised to evaluate the accuracy of pulse oximeters. Introduction of guidelines regarding the testing procedure would promote a uniform practice.
