The possible role of the vagal nervous system in the recovery of the blood pressure control after cardiac arrest: a porcine model study

Previous studies have proved that the baroreceptor reflex (baroreflex) control of heart rate can be used for stratification of post-infarction population and, in general, cardiovascular disease populations. Many methods have been proposed to estimate the so-called baroreflex sensitivity (BRS) expressed as ms mmhg(-1). Most of the studies that exploit BRS focus mainly on acute myocardial infarction (AMI) and there are no important works that investigate the role of BRS immediately after cardiac arrest (CA). The present work is a continuation of the published work of Ristagno et al (2014 Shock 41 72-8). In particular, the main objectives are: (1) to study the evolution of BRS after CA and following cardiopulmonary resuscitation (CPR); (2) to verify if the recovery of cardiovascular stability and arterial blood pressure is accompanied by a recovery of BR in a porcine model; (3) to investigate the possible causes of the BRS variations in response to CA and following cardiopulmonary resuscitation. All the BRS estimators adopted in this study show a significant decrease after CA. However, partial recovery is obtained in the last hours of post resuscitation. Analysis of impulse response showed a decrease in peak delay after CA and was significantly shorter 4 hours after CPR. This finding hints at a compensation mechanism: a faster response when baroreflex gain is not fully restored. The increase in the speed of baroreflex response is in line with the hypothesis of a key role of the parasympathetic nervous system, which is known to act at a higher firing rate.