Abstract 189: Characterizing Continuous Capnography at the Onset of Return of Spontaneous Circulation
BACKGROUND: Manual pulse checks are often unreliable and result in prolonged pauses in chest compressions, which may be deleterious to patient outcomes. Capnography has the potential to minimize these pauses, but the threshold for determining a pulse is not known.
METHODS: We conducted a prospective study of consecutive, adult, in-hospital cardiac arrests with documented return of spontaneous circulation (ROSC) at a single academic center between April 2006 and March 2012. CPR parameters and capnography were recorded using a CPR-sensing defibrillator equipped with sidestream capnography (HeartStart MRX with QCPR, Philips Healthcare; MicroStream, Oridion). All cases with continuous capnography and compression data for at least 2 minutes preceding ROSC were included in the analysis. End-tidal carbon dioxide (ETCO2) values were extracted electronically using custom software and the nadir and peak surrounding the last chest compression were manually identified.
RESULTS: A total of 69 cases met inclusion criteria. The median ETCO2 nadir was 14 mmHg (range 2 - 23), which rose to a median peak of 43 mmHg (range 21 - 98), yielding a median relative rise of 215% (range 44-1944). The figure displays the changes in ETCO2 before and after the peak. The median time from nadir to peak ETCO2 was 108 s (range 24 - 501), and the median rise was 0.25 mmHg/s (range 0.05 - 0.92). The peak occurred a median of -4.4 s relative to the last chest compression. At the end of chest compressions, the median ETCO2 was 29 mmHg (range 13 - 58), without a significant drop-off when compressions were held. At the end of chest compressions, the median ventilation and heart rate were 14/min (range 6 - 34) and 126/min (range 36 - 225), respectively.
CONCLUSION: In this sample, we found that ROSC was accompanied by an abrupt increase in ETCO2. This rise has the potential to be used as a pulse detector. Future work should assess whether the failure of this rise obviates the need for a pulse check.
- © 2012 by American Heart Association, Inc.