Association of sustained cardiovascular recovery with epinephrine in the delayed lipid-based resuscitation from cardiac arrest induced by bupivacaine overdose in rats

The role of epinephrine combined with lipid emulsion in rescuing cardiovascular collapse induced by local anaesthetic overdose remains unclear. The objective of this study was to explore the effect of epinephrine on delayed lipid-based treatment for bupivacaine-induced cardiac arrest in rats.Thirty-two rats were subjected to bupivacaine to induce asystole. Basic life support was performed for 10 min before the rats received saline, epinephrine alone, or 20% lipid emulsion bolus with or without epinephrine pretreatment. ECG and invasive arterial pressure were monitored continuously. Arterial blood gas was analysed at 25 min; the right lungs and hearts of rats were harvested for measurement of dry-to-wet lung weight ratio and myocardial bupivacaine content, respectively.In the rats treated with epinephrine plus lipid emulsion, there was a marked improvement in haemodynamic parameters at 25 min compared with rats treated with lipid alone, P<0.05. The coronary perfusion pressure immediately after lipid rescue was higher in the epinephrine/lipid-treated rats when compared with rats given lipid only (70 and 24 mm Hg, respectively, P<0.05). The myocardial bupivacaine content was lower (8.34 nM g(-1)) in the epinephrine/lipid group relative to other groups (P<0.05). However, the rats treated with lipid alone which survived had higher PO(2), less severe acidosis, and better hypoxaemia relative to surviving rats given epinephrine plus lipid.Late intervention with epinephrine plus lipid emulsion contributed to sustained improvement in haemodynamic profile, but failed to alleviate deterioration of hypoxaemia and acidaemia in rats.