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Updated: Jul 17, 2026

Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
Published on: January 29, 2011
Sidestream end-tidal carbon dioxide monitoring during helicopter transport
Daniel D Price1, Sharon R Wilson, Mary E Fee
1Department of Emergency Medicine, Oregon Health and Science University, Portland, OR, USA. danprice1@mac.com
Introduction:
End-tidal carbon dioxide (EtCO(2)) monitoring is standard of care for intubated patients. Sidestream technology also allows EtCO(2) monitoring in non-intubated patients. This is the first study to evaluate the feasibility of monitoring sidestream EtCO(2) on intubated and non-intubated patients during helicopter transport.
Setting:
An air medical transport program serving two level 1 trauma centers.
Methods:
In this prospective observational study, sidestream EtCO2 was monitored in 100 consecutive patients transported by helicopter. Flight nurses rated the difficulty posed by various factors of sidestream monitoring. An experienced flight nurse and a clinical engineer evaluated waveforms and EtCO(2) values.
Results:
Only 1 of the 100 transported patients required a change from sidestream to mainstream EtCO(2) monitoring. Moisture was noted in the tubing of two patients, and one was changed to mainstream. Eleven patients had occluded nares but were not changed to mainstream monitoring. On a 5-point Likert scale, responses to statements regarding difficulty with length of tubing, patient tolerance, and interference with patient care produced mean scores of 0.5 (range, 0-3). Responses regarding difficulty securing the cannula yielded a mean score of 0.7 (range, 0-3). Of 1,685 (99%) recorded EtCO(2) values, 1,668 met pre-established criteria for "consistent." Alveolar plateaus were identified in 81 of 94 (86%) patient waveforms by the flight nurse and 73 of 94 (78%) patient waveforms by the clinical engineer.
Conclusion:
Sidestream EtCO(2) monitoring is feasible during air medical transport of both intubated and non-intubated patients. The mechanism was easy to use, and consistent numeric values and waveforms with alveolar plateaus were obtained in a large majority of readings.
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