Currently, even in prehospital emergency medicine (PEM), continuous end-tidal CO 2 monitoring is frequently used as a sensitive and non-invasive technique in ventilated patients. Due to its central role, the continuous measurement of exhaled CO 2 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(TM)), and product information of all currently available capnometry devices were reviewed in detail. Firstly, the theoretical background of different CO 2-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 prehospital care are evaluated. Results: There are two basic principles to reliably determine end-tidal CO 2 (EtpCO 2) that can be realised in portable monitors: qualitative measurements with a paper indicator and quantitative measurements using nondispersive infrared spectroscopy. Capnography is a feature of more advanced units to provide the emergency physician with additional information by displaying EtpCO 2 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 CO 2 monitor, are described and evaluated for their use in PEM. Conclusions: Some current portable CO 2 monitors allow fast and reliable measurement of EtpCO 2 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, EtpCO 2, and peripheral O 2 saturation) seems to be a promising step for the improvement of monitoring in out-of-hospital emergencies.
- controlled ventilation
- emergency medicine
- measurement methods
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine