Essential monitoring examined through different lenses.

When we ask, what renders essential a particular monitoring approach during routine anesthesia for a healthy patient, perplexing questions, rather than satisfying answers, are raised. I have examined these questions with the help of three lenses that focus on the relationship between the outcome of anesthesia and the detection, and thus correction, of abnormalities during anesthesia. The first lens looks at whether the monitoring modalities accepted by anesthesiologists as "minimal" and "essential" have been scientifically proven to affect outcome from routine anesthesia. A second lens views how well monitors reveal the integrity of the organism and its components. Currently available monitors describe the output of cells or organs but relay little information about the viability of cells. Thus, they describe the symptoms rather than the causes of the pathophysiology related to anesthesia. Today's monitors also measure input, for example, the supply of oxygen, perhaps the most routinely measured of all the variables. The third lens looks at whether there are nonclinical influences on monitoring practice. This lens views the gap between recognizing monitoring possibilities and adopting them clinically; it also views geographic differences in monitoring, as well as social pressures exerted through legal proceedings. Finally, currently recognized essential monitors such as blood pressure measurement, electrocardiography, and oxygen analysis are mentioned, and candidates for inclusion in the list of essential monitors, such as oximeters, capnographs, and the automated record, are discussed.