Background:
The advent of highly sensitive End-Tidal CO2 (ETCO2) sensors allows effective monitoring of intubated patients in many emergency care settings, including EMS. Previous work has explored the use of ETCO2 monitoring in non-intubated patients with sensors placed in the nares. However, nothing is known about the effect of passive oxygen delivery [nasal cannula (NC) or non-rebreather mask (NRB)] on ETCO2 measurement.
Objective:
To compare ETCO2 measurements in non-intubated Traumatic Brain Injury (TBI) patients receiving O2 via NC vs NRB in the prehospital setting.
Methods:
A subset of major TBI cases (CDC Barell Matrix Type-1) in the Excellence in Prehospital Injury Care (EPIC) TBI Study (NIH/NINDS-1R01NS071049; ClinicalTrials.gov-NCT01339702) were evaluated 4/13-3/17). Non-intubated cases from 6 EMS agencies providing monitor data (Philips MRx) were included when continuous ETCO2 data were available. Statistics: Two-tailed t test, α = 0.05.
Results:
The 104 included cases had median age of 50.5 (range: 9-91; male: 67%). 39 (37.5%) received O2 via NC and 65 (62.5%) via NRB. Mean ETCO2: NC cases: 27.7 mmHg (95% CI: 25.7, 29.8); NRB: 30.0 (28.1, 31.8; p=0.132). There were also no significant differences among the mean lowest recorded values (p=0.449) or the mean highest values (p=0.275).
Conclusion:
We believe this is the first report comparing ETCO2 values based upon the method of passive O2 delivery in non-intubated patients. The minor differences between NC vs NRB-oxygenated patients was neither statistically nor clinically significant. This is surprising since: 1) the O2 flow rates and 2) the open-air (NC) vs mask (NRB) delivery methods are so dramatically different. Future study is needed to identify the clinical implications of using noninvasive ETCO2 measurement as a tool for monitoring ventilatory status and changes in non-intubated TBI (and other) patients.
End-tidal CO2 Monitoring is Available in Most Community Hospitals in a Rural State: A Health System Survey
