Abstract 94: Is the Impedance Cardiogram a Potential Indicator of Effective External Cardiac Massage in a Human Model? A Study to Establish If There Is a Linear Correlation Between the Impedance Cardiogram and Depth in a Cardiac Arrest Setting
Purpose of the Study: The 2010 AHA guidelines currently recommend a depth of at least 2 inches (5cm) during external cardiac massage. The purpose of this study was to assess the hypothesis that if using an alternative measure to depth could assist in quantifying the effectiveness of CPR in an out-of-hospital setting and to determine how achievable depths of at least 2 inches are in cardiac arrest patients.
Materials and Methods: A total of 32 cardiac arrest patients were recruited by EMS operators in Belfast and cardiologists in Craigavon Area Hospital (CAH). Patient baseline characteristics are summarised below in the results section. A subset of the patients enrolled had simultaneous recordings of Impedance Cardiogram (ICG) and depth (mm) during CPR. The Impedance Cardiogram (ICG)/Thoracic Impedance (non-invasive measure of cardiac output) was recorded via 2 standard defibrillation electrodes, as a method of detecting the presence of effective CPR. Ethical approval was granted by Ethical Committee Northern Ireland and the study was conducted in accordance with ISO 14155:2011; GCP standards. Depth and rate of CPR were continuously measured using Q-CPR®, Philips. CPR was administered manually by trained ALS operators. Recordings from each experiment were acquired using Philips Q-CPR review software and HeartSine download software for statistical analysis using R®.
Results: Patients were aged between 32 and 93 years (mean 77 years), 64% of this cohort was male. Excluding cases CPR traces with excessive motion artefact, a total of 1883 compressions were administered in patients with a mean weight of 73.85kg. The mean compression depth achieved was 1.79 inches. A strong linear correlation was achieved between depth (mm) using Q-CPR® and the Impedance cardiogram (ICG)/ thoracic impedance (ohms); r=0749.
Conclusions: It can be concluded that a depth of 2 inches is difficult to achieve both in-hospital and by EMS operators even with the support of real-time CPR feedback. An algorithm will incorporate the results from this study, providing feedback to the operator on the quality of CPR by measuring the ICG amplitude which has been strongly correlated with standard measures of depth as well as a number of physiological parameters.
- Cardiopulmonary resuscitation
- Cardiac arrest
- Emergency care
- Acute coronary syndromes
- Arrhythmias, treatment of
- © 2012 by American Heart Association, Inc.