Review Article: Metrology in Medicine: From Measurements to Decision, with Specific Reference to Anesthesia and Intensive Care

The International Bureau of Weights and Measures defines metrology as the science of measurement, embracing both experimental and theoretical determinations at any level of uncertainty in any field of science and technology.1 Measurements of physiological, biochemical, physical, and other patient-related variables are not only ubiquitous in intensive care medicine and beyond, but the results from such measurements also provide essential information for critical decision-making in clinical practice, as well as for research and technology development. Erroneous measurements can jeopardize patient safety and can expose the most critically ill patients to severe hazards. If physiological variables cannot be measured properly, then therapy-targeting changes in those variables cannot be adjusted properly. Understanding metrological concepts and recognizing limitations and constraints help to interpret clinical study results and in technological assessment of new medical devices. It is crucially important that physicians share with other scientists the same understanding of objectives, terms, units, and criteria attributed to measurements. This is of particular importance in anesthesiology and intensive care medicine, owing to the large and increasing number of medical devices that are involved in clinical decision-making. This review addresses the most frequent metrological misunderstandings encountered in critical care and their impact on daily practice. Following other authors,2 it is also a plea for avoiding frequent ambiguity in the use of terms and aligning our terminology to the most recent common standards. Finally and most importantly, we try to provide guidance for metrological concepts and their relevance for clinical decision-making.