To evaluate three prototype versions of semi-quantitative end-tidal CO2 monitors with different alarm features during prehospital or inter-facility use.

Subjects were 43 adult, non-pregnant patients requiring intubation, or who already were intubated and required transport. Teams at one AirEvac and seven Advanced Life Support (ALS) paramedic stations were trained in the use of the monitors. Team members at each station evaluated each model for eight days. Participants completed questionnaires following each use.

The monitors performed properly in all cases, but in one case, vomit in the airway adapter tube prevented obtaining a readout. The monitors aided management in 40 of 43 cases (93%); in one, the monitor reading was reported as variable (between 20 and 30 mmHg) although the teams knew the monitors were semi-quantitative; in another, the monitor was not required, but performed properly; and the third was the one in which vomit in the tube prevented a reading. In 26 of 43 cases (60.4%), the monitor was used to confirm endotracheal tube placement (there were no instances of incorrect placement). In all cases, the devices were used to monitor respiration and oxygen saturation. Alarms were audible in the environment, but only preferred in the AirEvac situation. The “breath beep” feature was useful, particularly in patients in whom chest movements during respiration were difficult to observe.

“Breath beeps” were clearly audible and were a useful feature in all prehospital and transport environments, while audible alarms were desired only in the AirEvac situation. Semi-quantitative CO2 detection is valuable in the ALS/AirEvac environment, even for teams with high intubation success rates.