Processing, storage and display of physiological measurements

Modern anaesthesia demands the monitoring of many biological variables. It is no longer sufficient to be satisfied by a patient of good colour with a temporal pulse of reasonable character, volume and rate, though in times of power loss and technological malfunction these are skills that may still be relied upon! The journey of a biological variable from patient to monitor requires several distinct processes, often imagined within a singular 'black box': (i) detection; (ii) transduction; (iii) processing; (iv) display; (v) storage. The aim of this article is to examine each of these elements in turn, to inspect the ways in which different biological variables require distinct handling techniques and to give running examples to portray each step in a way applicable to daily practice.