Medic and Portable Pulse Oximeter Respiratory Rate Measurement Comparison to Waveform Capnography: A Prospective, Observational Study.

Background: The second leading cause of preventable battlefield death involves airway management. Tactical combat casualty care (TCCC) guidelines emphasize combat casualty airway, breathing and respiratory evaluation, including respiratory rate (RR) measurement. The current standard of practice for the US Army medics is to measure the RR by manual counting. Manual counting methods are operator-dependent, and medics face situational stressors limiting accurate measurement of RR in combat settings. To date, no published studies evaluate alternate methods of RR measurement by medics. The purpose of this study is to compare RR assessment by medics against waveform capnography and commercial finger pulse oximeters with continuous plethysmography.

Materials and methods: We conducted a prospective, observational study to compare Army medic RR assessments against plethysmography and waveform capnography RR. Assessments were performed prior to and following exertion at 30 and 60 seconds with both the pulse oximeter (NSN 6515-01-655-9412) and defibrillator monitor (NSN 6515-01-607-8629), followed by end-user surveys.

Results: Of the 40 medics enrolled over a 4-month period, most were male (85%), and reported between less than 5 years of military and medical experience. The mean manual RR reported by medics at rest did not significantly differ from waveform capnography (14.05 versus 13.98, p is equal to 0.523); however, mean manual RR reported by medics on post-exertional subjects was significantly lower than waveform capnography (25.62 versus 29.77, p is less than 0.001). Time to medic-obtained RR was slower than the pulse oximeter (NSN 6515-01-655-9412) both at rest (-7.37 seconds, p is less than 0.001) and at exertion (-6.50 seconds, p is less than 0.001). While the mean difference in RR between the pulse oximeter (NSN 6515-01-655-9412) and waveform capnography in models at rest at 30 seconds was statistically significant (-1.38, p is less than 0.001). There was no overall statistically significant differences in RR between the pulse oximeter (NSN 6515-01-655-9412) and waveform capnography in models at exertion at 30 seconds and at rest and exertion at 60 seconds.

Conclusion: Resting RR measurement did not differ significantly; however, medic-obtained RR considerably deviated from both pulse oximeters and waveform capnography at elevated rates. Existing commercial pulse oximeters with RR plethysmography do not differ significantly from waveform capnography and should be investigated further for consideration in fielding across the force for RR assessment.