Abstract 166: Physiological Effects of Adrenaline in Human Cardiac Arrest With Pulseless Electrical Activity: A Pilot Study

Abstract

Introduction: During resuscitation from cardiac arrest with Pulseless Electrical Activity (PEA), studies show that adrenaline facilitates return of spontaneous circulation (ROSC) and possibly leads to an isolated increase in the heart rate (HR). In this study, we investigated the immediate effects of adrenaline on ECG characteristics; HR and QRS duration (duration of ventricle depolarization). Method: We studied 19 ECG segments of 300 s duration from emergency defibrillators in 10 adult patients during resuscitation from in-hospital cardiac arrest. Information on the exact timing of adrenaline administration (between 0.5 and 1 mg i.v.) was obtained from the defibrillators or the emergency personnel involved. HR (1/min) and QRS duration (ms) were annotated and registered using an ad-hoc Matlab (Mathworks, Natic, MA) graphical Data Annotator, and interpolated linearly between individual observations. Trends were identified with LOWESS. Results: The plots show the individual observations (red points) along with the trends (blue lines) of HR and QRS Duration during resuscitation, relative to the time of adrenaline administration. We observed a gradual increase in heart rate (peaking at 150 s after adrenaline administration) and a more pronounced narrowing of the QRS (levelling off also at about 150 s). Discussion: In this pilot study, administration of adrenaline was associated with narrowing of the QRS complex, while the relation to heart rate was less apparent. A limitation is that no adjustment for the individual patient’s trajectory was made. However, the results are fairly consistent with earlier studies on out-of-hospital resuscitation, when adrenaline was typically given much later.