Pulse oximetry: an equipment management perspective

Spurred on by operational simplicity, decreasing cost, and the importance of knowing the arterial blood oxygen content, pulse oximeter usage increased rapidly since its development in the early 1980´s. Professional bodies recommend its use during surgical procedures and evidence suggests that their usage improves the safety of surgical procedures and reduces the need to take arterial blood samples. In major teaching hospital records show a growth in number of units per hundred hospital beds from less than 0.5 early 1987 to over 13 in April 1996. The principles behind the operation of the pulse oximeter are deceptively simple. Oxygenated and reduced haemoglobin have different optical spectra for red and infrared light. The oxygen saturation of the arterial blood is determined from the ratio of the pulsatile component of the red to the pulsatile component of the infra-red light transmitted through the vascular bed. The management of this new technology requires an understanding of the principles of operation, limitations in its use, purchase considerations and maintenance issues. It has been suggested that pulse oximeters do not requiring routine calibration. However, like all electromedical equipment basic safety and functional checks are required. Test simulators are now available, based either on detecting and regenerating the bursts of red and infra-red light, or based on placing with the probe an artificial finger whose spectral characteristics to red and infra-red light may be varied-both mechanical and liquid crystal systems have been described