[End-tidal CO2 measurement in anesthetic gases. An important global measurement in emergency medicine: theoretical background, indications and overview of available, transportable measurement systems].
Currently, even in prehospital emergency medicine (PEM), continuous end-tidal CO2 monitoring is frequently used as a sensitive and non-invasive technique in ventilated patients. Due to its central role, the continuous measurement of exhaled CO2 provides immediate information about the status of three essential functions of the organism: ventilation, circulation, and metabolism.


METHODS
Recent literature, obtained by a computer-guided search (Winspirs), and product information of all currently available capnometry devices were reviewed in detail. Firstly, the theoretical background of different CO2-measurement methods and techniques is described. Secondly, indications and specific implications for the out-of-hospital use of capnometry are discussed. Thirdly, different monitoring systems suitable for pre-hospital care are evaluated.


RESULTS
There are two basic principles to reliably determine end-tidal CO2 (EtpCO2) that can be realised in portable monitors: qualitative measurements with a paper indicator and quantitative measurements using non-dispersive infrared spectroscopy. Capnography is a feature of more advanced units to provide the emergency physician with additional information by displaying EtpCO2 values versus time. Multiple indications for capnometry in emergency situations are listed, all related to the evaluation of patient's ventilation, circulation, and metabolism. Specific implications regarding mobility, ease of use, patient hygiene and accuracy of measurements are mentioned. Five units, each representing a different type of CO2 monitor, are described and evaluated for their use in PEM.


CONCLUSIONS
Some current portable CO2 monitors allow fast and reliable measurement of EtpCO2 even in the out-of-hospital care of critically ill patients. However, the development of a new portable monitoring system comprising the three most important ventilation parameters (ventilation rate, EtpCO2 and peripheral O2 saturation) seems to be a promising step for the improvement of monitoring in out-of-hospital emergencies.
Brambrink
A M
AM
Klinik für Anästhesiologie, Johannes Gutenberg-Universität Mainz.
D002245:Carbon Dioxide / Q000032:analysis*; D004632:Emergency Medical Services / Q000379:methods*; D006801:Humans
D002245:Carbon Dioxide