Identifying the circulation state during 1 out-of-hospital cardiac arrest (OHCA) is essential to determine 2 what life-saving therapies to apply. Currently algorithms 3 discriminate circulation (pulsed rhythms, PR) from no circulation 4 (pulseless electrical activity, PEA), but PEA can be classified 5 into true (TPEA) and pseudo (PPEA) depending on cardiac 6 contractility. This study introduces multi-class algorithms to 7 automatically determine circulation states during OHCA using 8 the signals available in defibrillators. Methods: A cohort of 9 60 OHCA cases were used to extract a dataset of 2506 5-s 10 segments, labeled as PR (1463), PPEA (364) and TPEA (679) 11 using the invasive blood pressure, experimentally recorded 12 through a radial/femoral cannulation. A multimodal algorithm 13 using features obtained from the electrocardiogram, the thoracic 14 impedance and the capnogram was designed. A random forest 15 model was trained to discriminate three (TPEA/PPEA/PR) and 16 two (PEA/PR) circulation states. The models were evaluated 17 using repeated patient-wise 5-fold cross-validation, with the 18 unweighted mean of sensitivities (UMS) and F1-score as 19 performance metrics. Results: The best model for 3-class had 20 a median (interquartile range, IQR) UMS and F1 of 69.0% 21 (68.0-70.1) and 61.7% (61.0-62.5), respectively. The best two class 22 classifier had median (IQR) UMS and F1 of 83.9% (82.9-84.5) 23 and 76.2% (75.0-76.9), outperforming all previous proposals 24 in over 3-points in UMS. Conclusions: The first multiclass 25 OHCA circulation state classifier was demonstrated. The method 26 improved previous algorithms for binary pulse/no-pulse decisions.
Compressions during the insufflation phase of ventilations may cause severe pulmonary injury during cardiopulmonary resuscitation (CPR). Transthoracic impedance (TTI) could be used to evaluate how chest compressions are aligned with ventilations if the insufflation phase could be identified in the TTI waveform without chest compression artifacts. Therefore, the aim of this study was to determine whether and how the insufflation phase could be precisely identified during TTI. We synchronously measured TTI and airway pressure (Paw) in 21 consenting anaesthetised patients, TTI through the defibrillator pads and Paw by connecting the monitor-defibrillator’s pressure-line to the endotracheal tube filter. Volume control mode with seventeen different settings were used (5–10 ventilations/setting): Six volumes (150–800 mL) with 12 min−1 frequency, four frequencies (10, 12, 22 and 30 min−1) with 400 mL volume, and seven inspiratory times (0.5–3.5 s ) with 400 mL/10 min−1 volume/frequency. Median time differences (quartile range) between timing of expiration onset in the Paw-line (PawEO) and the TTI peak and TTI maximum downslope were measured. TTI peak and PawEO time difference was 579 (432–723) m s for 12 min−1, independent of volume, with a negative relation to frequency, and it increased linearly with inspiratory time (slope 0.47, R 2 = 0.72). PawEO and TTI maximum downslope time difference was between −69 and 84 m s for any ventilation setting (time aligned). It was independent ( R 2 < 0.01) of volume, frequency and inspiratory time, with global median values of −47 (−153–65) m s , −40 (−168–68) m s and 20 (−93–128) m s , for varying volume, frequency and inspiratory time, respectively. The TTI peak is not aligned with the start of exhalation, but the TTI maximum downslope is. This knowledge could help with identifying the ideal ventilation pattern during CPR.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.