In a pig model of hemorrhagic shock, autonomic control of blood pressure was highly impaired and not completely recovered after initial resuscitation despite restoration of mean pressures.
Does resuscitation with fluids, norepinephrine, and blood reinfusion restore autonomic control and heart functionality in a pig model of severe hemorrhagic shock?
In a pig model of hemorrhagic shock, autonomic control and myocardial stress markers are not fully normalized by restoring mean blood pressure alone, highlighting the value of variability indexes as resuscitation endpoints.
Autonomic control of blood pressure (BP) and heart rate (HR) is crucial during bleeding and hemorrhagic shock (HS) to compensate for hypotension and hypoxia. Previous works have observed that at the point of hemodynamic decompensation a marked suppression of BP and HR variability occurs, leading to irreversible shock. We hypothesized that recovery of the autonomic control may be decisive for effective resuscitation, along with restoration of mean BP. We computed cardiovascular indexes of baroreflex sensitivity and BP and HR variability by analyzing hemodynamic recordings collected from five pigs during a protocol of severe hemorrhage and resuscitation; three pigs were sham-treated controls. Moreover, we assessed the effects of severe hemorrhage on heart functionality by integrating the hemodynamic findings with measures of plasma high-sensitivity cardiac troponin T and metabolite concentrations in left ventricular (LV) tissue. Resuscitation was performed with fluids and norepinephrine and then by reinfusion of shed blood. After first resuscitation, mean BP reached the target value, but cardiovascular indexes were not fully restored, hinting at a partial recovery of the autonomic mechanisms. Moreover, cardiac troponins were still elevated, suggesting a persistent myocardial sufferance. After blood reinfusion all the indexes returned to baseline. In the harvested heart, LV metabolic profile confirmed the acute stress condition sensed by the cardiomyocytes. Variability indexes and baroreflex trends can be valuable tools to evaluate the severity of HS, and they may represent a more useful end point for resuscitation in combination with standard measures such as mean values and biological measures. NEW & NOTEWORTHY Autonomic control of blood pressure was highly impaired during hemorrhagic shock, and it was not completely recovered after resuscitation despite global restoration of mean pressures. Moreover, a persistent myocardial sufferance emerged from measured cardiac troponin T and metabolite concentrations of left ventricular tissue. We highlight the importance of combining global mean values and biological markers with measures of variability and autonomic control for a better characterization of the effectiveness of the resuscitation strategy.
Carrara et al. (Thu,) conducted a other in Severe hemorrhagic shock (n=8). Severe hemorrhage and resuscitation vs. Sham-treated controls was evaluated on Cardiovascular indexes of baroreflex sensitivity, BP and HR variability, cardiac troponin T, and LV metabolite concentrations. In a pig model of hemorrhagic shock, autonomic control of blood pressure was highly impaired and not completely recovered after initial resuscitation despite restoration of mean pressures.