Abstract 248: When Does Expiration End? Comparison of Two Criteria for Measuring End-tidal Co 2
| Autor: | Camilo L Sandoval, Luis A. Leturiondo, Mohamud Daya, James K. Russell, José Julio Gutiérrez, Jesus Ruiz, Izaskun Azkarate, Sofía Ruiz de Gauna |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Circulation. 142 |
| ISSN: | 1524-4539 0009-7322 |
| DOI: | 10.1161/circ.142.suppl_4.248 |
| Popis: | Aim: End-tidal CO2 is defined as the partial pressure of carbon dioxide in exhaled air at the end of expiration. During CPR with manual ventilation, end-tidal CO2 is generally measured as the maximum CO2 value during the expiratory plateau of the capnogram. Transthoracic impedance (TTI) acquired through defibrillation pads also allows for tracking inspiratory and expiratory phases during CPR. Our aim was to compare the CO2 value measured at the end of the TTI expiration with the maximum CO2 value in the capnogram plateau. Materials and methods: Fifteen out-of-hospital cardiac arrest defibrillation recordings (Tualatin Valley Fire & Rescue, Oregon, USA) containing concurrent TTI and capnogram were analyzed. TTI signal was filtered to isolate the fluctuations caused by ventilations from those caused by chest compressions or spontaneous circulation. Inspiratory and expiratory intervals per ventilation were marked in the TTI. Values of CO2 at the end of the TTI expiratory interval and the maximum value in the capnogram expiratory plateau were annotated. Results: A total of 3559 ventilations were analyzed. Median (IQR) ventilation rate was 17.1 (11.2, 22.9) min-1. Median ventilation duration was 2.4 (2.1, 2.9) s, and inspiration represented the 45.5 (40.2, 49.9) % of the ventilation duration. CO2 value at the end of TTI expiration was 24.5 (14.7, 34.1) mmHg. Difference with respect to the maximum capnogram CO2 was 2.1 (0.7, 4.4) mmHg. More importantly, we found differences higher than 7.5 mmHg (29.1%) in 10% of the annotated ventilations. In the figure, both values match in the first ventilation but not in the second, where the difference between CO2 values is 15.4%. Conclusion: Median differences between CO2 concentration at the end of the TTI expiratory phase and the maximum tidal value in the capnogram were small. However, the observed important differences require further exploration. |
| Databáze: | OpenAIRE |
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