Robust Segmentation of CPR-Induced Capnogram Using U-net: Overcoming Challenges with Deep Learning

Objective: The accurate segmentation of capnograms during cardiopulmonary resuscitation (CPR) is essential for effective patient monitoring and advanced airway management. This study aims to develop a robust algorithm using a U-net architecture to segment capnograms into inhalation and non-inhalation phases, and to demonstrate its superiority over state-of-the-art (SoA) methods in the presence of CPR-induced artifacts. Materials and methods: A total of 24354 segments of one minute extracted from 1587 patients were used to train and evaluate the model. The proposed U-net architecture was tested using patient-wise 10-fold cross-validation. A set of five features was extracted for clustering analysis to evaluate the algorithm performance across different signal characteristics and contexts. The evaluation metrics included segmentation-level and ventilation-level metrics, including ventilation rate and end-tidal-CO$_2$ values. Results: The proposed U-net based algorithm achieved an F1-score of 98% for segmentation and 96% for ventilation detection, outperforming existing SoA methods by 4 points. The root mean square error for end-tidal-CO$_2$ and ventilation rate were 1.9 mmHg and 1.1 breaths per minute, respectively. Detailed performance metrics highlighted the algorithm's robustness against CPR-induced interferences and low amplitude signals. Clustering analysis further demonstrated consistent performance across various signal characteristics. Conclusion: The proposed U-net based segmentation algorithm improves the accuracy of capnogram analysis during CPR. Its enhanced performance in detecting inhalation phases and ventilation events offers a reliable tool for clinical applications, potentially improving patient outcomes during cardiac arrest.