Tossicità sistemica degli anestetici locali. Trattamento con emulsione lipidica

Background: Lipid emulsion infusion reverses cardiovascular compromise due to local anesthetic overdose in laboratory and clinical settings. The author compared the efficacy of resuscitation from bupivacaine-induced asystole using lipid emulsion infusion versus epinephrine, vasopressin, combination of epinephrine and vasopressin, and saline control in a prospective randomized animal study. Methods: Bupivacaine was infused in male Spregue-Dawley rats anesthetized with isoflurane, producing asystole in all subjects. Rats were ventilated with 100% oxygen, given chest compression, and randomized to receive 30% lipid emulsion, vasopressin, epinephrine alone or combined with vasopressin, and saline. Treatment boluses were repeated at 2.5 and 5 minutes for a native rate-pressure product less than 20% baseline. Electrocardiogram and arterial blood pressure were monitored continuously and at 10 min arterial blood gas, central venous oxygen saturation and blood lactate were measured. Results: Lipid infusion resulted in higher rate-pressure product, pH and central venous oxygen saturation than in vasopressors groups and in control group at 10 min. Metrics indicated better tissue perfusion in lipid group than in the others group. Epinephrine treatment caused persistent ventricular ectopy in all subjects. Vasopressin and epinephrine were associated with developing of pulmonary edema. Conclusion: Lipid emulsion in this rat model provide superior hemodynamic and metabolic recovery from bupivacaine-induced cardiac arrest than do vasopressors. Vasopressin and epinephrine were associated with adverse outcomes. Systolic pressure was not an useful metric in the vasopressors group. Further studies are required to optimize the clinical management of systemic local anesthetic toxicity.

E’ stato precedentemente dimostrato il recupero di attività cardiaca spontanea dopo l’infusione di una emulsione lipidica (30% soy oil emulsion) in seguito ad arresto cardiaco bupivacaina-indotto sia in vivo sia in modelli sperimentali di cuore isolato. Numerosi case reports sono stati pubblicati sull’utilizzo clinico dell’emulsione lipidica nella rianimazione di pazienti in arresto cardiaco in seguito ad overdose di anestetico locale. Le linee guida 2005 dell’American Heart Association (AHA/ACLS resucitation protocol) prevedono l’utilizzo di una dose di 40 U di vasopressina, al posto della prima o seconda dose di epinefrina, come farmaco di prima linea nel trattamento dell’arresto cardiaco. Abbiamo studiato l’efficacia dell’emulsione lipidica versus i farmaci suggeriti dai protocolli ACLS in un modello sperimentale di arresto cardiaco bupivacaina-indotto in ratti. Sono stati analizzati parametri emodinamici, metabolici ed elettrocardiografici. L’emulsione lipidica è risultata superiore, in termini di sopravvivenza, parametri emodinamici e metabolici, all’adrenalina, alla vasopressina e alla loro associazione nel trattamento dell’arresto cardiaco indotto da un’overdose di bupivacaina. Ulteriori studi sono necessari per confermare queste osservazioni e soprattutto per determinare eventuali implicazioni sul piano clinico.