Comparison of Vasopressin versus Norepinephrine in a Pig Model of Refractory Cardiogenic Shock Complicated by Cardiac Arrest and Resuscitated with Veno-Arterial ECMO.

BACKGROUND The choice of the best vasopressor after ECMO implantation after cardiac arrest is not well defined. Circulatory flow recovery with ECMO is associated with vasoplegia and vasopressor need. The present study aimed to compare the effects of norepinephrine and vasopressin in the first six hours after ECMO initiation. METHODS Cardiac arrest was induced in 20 pigs by coronary surgical ligature and VA-ECMO was started after a 30-min period of cardio-pulmonary resuscitation. Pigs were randomised into two groups, AVP or NE, with the drugs titrated to maintain a MAP at 65 mmHg. Macrocirculatory and metabolic parameters were assessed by lactate clearance. Microcirculatory parameters were assessed by sublingual microcirculation with Sidestream Dark Field (SDF) imaging and peripheral Near InfraRed Spectroscopy (NIRS). Pulmonary oedema was evaluated by measuring lung wet/dry weight ratio. RESULTS No difference was found between groups regarding ECMO flow and Mean Arterial Pressure. Fluid resuscitation volume was higher in the NE group (14000 [11250-15250] mL versus 3500 [1750 - 4000] mL in the AVP group, p < 0.05). Lung wet/dry weight ratio was higher in the Norepinephrine group. Lactate clearance between H0 and H6 was higher in the AVP group (47.84 [13.42 - 82.73] % versus the NE group 25.66 [-7.31 - 35.34) % vs., p < 0.05). No significant difference was observed for sublingual microcirculation values. Baseline tissue oxygen saturation was comparable and higher at both H3 and H6 in the Vasopressin group comparatively to the Norepinephrine group (p < 0.05) (Table 5). Renal and liver function evolution also remained similar in the two groups throughout the study. CONCLUSIONS AVP administration in refractory cardiac arrest resuscitated by VA-ECMO is associated with a faster lactate clearance, less fluid resuscitation and less pulmonary oedema when compared to NE for similar global and regional hemodynamic effects.