# A novel algorithm to determine ventilation parameters during cardiopulmonary resuscitation using pneumotachography waveform data

## TL;DR

This paper introduces a new algorithm to measure ventilation parameters during CPR, overcoming issues caused by chest compressions.

## Contribution

The novel algorithm enables accurate ventilation parameter extraction during CPR using pneumotachography waveform data.

## Key findings

- The algorithm overestimates peak pressures during asynchronous CPR with a median error of 3 cmH2O.
- It underestimates inspiratory volumes during synchronous CPR with a median error of 46 ml.
- The algorithm is open-source and provides a novel solution for ventilation measurement during chest compressions.

## Abstract

A major barrier to the analysis of ventilation waveform data collected during CPR is the presence of artefacts caused by chest compressions. This study describes the development and evaluation of an algorithm to extract parameters regarding ventilation volume, pressure, and frequency from pneumotachography waveform data collected during ongoing simulated CPR.

Ventilation waveform data was collected from a pneumotachograph connected to the respiratory circuit of a ventilator and a test lung. Both regular ventilation and ventilation during simulated CPR were used to develop the algorithm. A grid search was employed to optimize the algorithm parameters compared to the ventilator settings. The parameters were then manually tuned using clinical data from ventilation during CPR. The performance of the algorithm was described in terms of the median error vs. the known ventilator settings in the simulated data.

Compared to the ventilator settings, the largest systematic errors of the algorithm was an overestimation of peak pressures during asynchronous CPR (median error of 3 (IQR 0.3–5.8) cmH2O), and an underestimation of inspiratory volumes during synchronous CPR (median error 46 (IQR −76 to 10) ml).

In an experimental setting, the developed algorithm provides a novel solution to measure ventilation parameters during ongoing chest compressions. The algorithm is freely available under an open-source licence for use and further development. Further studies will be needed to validate the algorithm.