Transcutaneous PCO2: why, how and for whom?

Abstract

Measurement of the transcutaneous pressure of carbon dioxide (PtcCO₂) is not a recent technology, as the first studies were conducted in the 1960s. Since then, improvements in the monitors and electrodes, together with greater miniaturization, have made continuous PtcCO₂ a reliable, noninvasive, simple, and rapid measurement available for everyday clinical use. PtcCO₂ monitoring is a simple mean for estimating the arterial CO₂ partial pressure (PaCO₂), which is invaluable in several clinical situations. Currently available PtcCO₂ monitors are reliable and can be coupled with other parameters (SpO₂, breathing rate, heart rate, tissue perfusion index…) to produce a rapid and noninvasive assessment of respiratory function and, more importantly, to monitor respiratory function over time. The current preference for noninvasive monitoring in the intensive care unit has driven the development of new technologies; however, caution is mandatory to avoid any abusive or inappropriate use. Given the fast-expanding array of available technologies and the abundant publications in this field, an overview of PtcCO₂ monitoring appears useful. We describe here the available devices and discuss their advantages and limits, as well as the potential fields of their application.