Ventricular fibrillation waveform properties influenced by thoracic impedance guided chest compressions in a porcine model

Olibhéar McAlister; Adam Harvey; Ben McCartney; Paul Crawford; Raymond R Bond; Dewar D Finlay; David McEneaney

doi:10.1016/j.cmpb.2023.107780

Ventricular fibrillation waveform properties influenced by thoracic impedance guided chest compressions in a porcine model

Comput Methods Programs Biomed. 2023 Nov:241:107780. doi: 10.1016/j.cmpb.2023.107780. Epub 2023 Aug 25.

Authors

Olibhéar McAlister¹, Adam Harvey², Ben McCartney³, Paul Crawford⁴, Raymond R Bond⁵, Dewar D Finlay⁵, David McEneaney⁶

Affiliations

¹ Ulster University, Belfast, UK; HeartSine Technologies Ltd., Belfast, UK. Electronic address: olibhear.mcalister@stryker.com.
² HeartSine Technologies Ltd., Belfast, UK.
³ Ulster University, Belfast, UK; HeartSine Technologies Ltd., Belfast, UK.
⁴ Veterinary Anaesthesia Consultancy, UK.
⁵ Ulster University, Belfast, UK.
⁶ Craigavon Area Hospital, Craigavon, UK.

PMID: 37651816
DOI: 10.1016/j.cmpb.2023.107780

Abstract

Background and objective: Quantitative measures extracted from ventricular fibrillation (VF) waveform reflect the metabolic state of the myocardium and are associated with survival outcome. The quality of delivered chest compressions during cardiopulmonary resuscitation are also linked with survival. The aim of this research is to explore the viability and effectiveness of a thoracic impedance (TI) based chest compression (CC) guidance system to control CC depth within individual subjects and influence VF waveform properties.

Methods: This porcine investigation includes an analysis of two protocols. CC were delivered in 2 min episodes at a constant rate of 110 CC min^-1. Subject-specific CC depth was controlled using a TI-thresholding system where CC were performed according to the amplitude (Z_RMS, 0.125 to 1.250 Ω) of a band-passed TI signal (Z_CC). Protocol A was a retrospective analysis of a 12-porcine study to characterise the response of two VF waveform metrics: amplitude spectrum area (AMSA) and mean slope (MS), to varying CC quality. Protocol B was a prospective 12-porcine study to determine if changes in VF waveform metrics, due to CC quality, were associated with defibrillation outcome.

Results: Protocol A: A directly proportional relationship was observed between Z_RMS and CC depth applied within each subject (r = 0.90; p <0.001). A positive relationship was observed between Z_RMS and both AMSA (p <0.001) and MS (p <0.001), where greater TI thresholds were associated with greater waveform metrics.

Protocol b: MS was associated with return of circulation following defibrillation (odds ratio = 2.657; p = 0.043).

Conclusion: TI-thresholding was an effective way to control CC depth within-subjects. Compressions applied according to higher TI thresholds evoked an increase in AMSA and MS. The response in MS due to deeper CC resulted in a greater incidence of ROSC compared to shallow chest compressions.

Keywords: Amplitude spectrum area; Chest compressions; Mean slope; Quantitative waveform measures; Thoracic impedance; Ventricular fibrillation.

MeSH terms

Amsacrine*
Animals
Electric Impedance
Prospective Studies
Retrospective Studies
Swine
Ventricular Fibrillation* / therapy

Substances

Amsacrine