ABSTRACT
PURPOSE: To evaluate hemodynamic changes caused by sole intravenous infusion of lipid emulsion with doses recommended for treatment of drug-related toxicity. METHODS: Large White pigs underwent general anesthesia, tracheal intubation was performed, and mechanical ventilation was instituted. Hemodynamic variables were recorded using invasive blood pressure and pulmonary artery catheterization. Baseline hemodynamic measurements were obtained after a 30-minute stabilization period. An intravenous bolus injection of 20% lipid emulsion at 1.5 ml/kg was administered. Additional hemodynamic measurements were made after 1 minute, followed by a continuous intravenous lipid infusion of 0.25 ml/kg/min. Further measurements were carried out at 10, 20 and 30 minutes, when the infusion was doubled to 0.5 ml/kg/min. Assessment of hemodynamic changes were then made at 40, 50 and 60 minutes. RESULTS: Lipid infusion did not influence cardiac output or heart rate, but caused an increase in arterial blood pressure, mainly pulmonary blood pressure due to increased vascular resistance. Ventricular systolic stroke work consequently increased with greater repercussions on the right ventricle. CONCLUSION: In doses used for drug-related toxicity, lipid emulsion cause significant hemodynamic changes with hypertension, particularly in the pulmonary circulation and increase in vascular resistance, which is a factor to consider prior to use of these solutions.
Subject(s)
Animals , Drug-Related Side Effects and Adverse Reactions/therapy , Fat Emulsions, Intravenous/pharmacology , Hemodynamics/drug effects , Body Weight , Disease Models, Animal , Heart Ventricles/drug effects , Hemodynamics/physiology , Infusions, Intravenous , Reference Values , Swine , Time FactorsABSTRACT
La toxicidad sistémica por sobredosis de anestésico local es una complicación rara pero potencialmente devastadora de la anestesia regional y central neuraxial. El colapso cardiovascular que sigue a la toxicidad sistémica por sobredosis de anestésico local, especialmente la bupivacaína, es extremadamente difícil de tratar usando los fármacos estándares de resucitación, con el potencial resultado de paro cardíaco refractario a esta acción. La terapia con emulsión lipídica puede restaurar rápidamente la circulación luego del colapso cardiovascular inducido por anestésicos locales. Modelos experimentales de toxicidad por anestésicos locales han mostrado un retorno acelerado de la función cardíaca espontánea posterior a una infusión lipídica, tanto en animales intactos como en corazones aislados. Varios reportes de caso se refieren a la extensión de estos hallazgos al área clínica, citando rápidas resucitaciones con lípidos de sujetos con paro cardíaco luego de una anestesia regional. El tratamiento precoz con emulsión lipídica de pacientes con signos neurológicos puede prevenir la parada cardíaca o acelerar el retorno del latido cardíaco espontáneo. Cuando se presenta un individuo con signos de severa toxicidad por anestésico local (inconsciencia, convulsiones tónico-clónicas, colapso cardiovascular), se debe suspender la inyección de anestésico local, pedir ayuda, mantener la vía aérea permeable, administrar oxígeno al 100 por ciento, mantener una adecuada ventilación pulmonar, lograr el control de las convulsiones (benzodiazepinas, tiopental o propofol en dosis incrementales), comenzar una reanimación, administrar bolo intravenoso de Intralipid ® 20 por ciento, 1,5 ml/kg en 1 minuto, continuar RCP, comenzar la infusión intravenosa de Intralipid ® 20 por ciento,0,25 ml/kg.min, continuar RCP y repetir el bolo dos veces con intervalos de 5 minutos si no se restauró una adecuada circulación...
Systemic toxicity caussed by overdose of local anesthetics is a rare complication but it is potentially devastating in regional and central neuraxial anesthesia. The cardiovascular collapse that follows systemic toxicity due to local anesthetics, particularly bupivacaine, is extremely hard to treat with standard resuscitation drugs, with the potential result of treatment-resistant cardiac arrest. Treatment with lipidic emulsion can rapidly restore circulation after cardiovascular collapse induced by local anesthetics. Experimental models of toxicity due to local anesthetics have shown a fast return of spontaneous cardiac function following a lipidic infusion in intact animals as web as in isolated hearts. Several case reports refer to this findings extended to the clinical area, citing fast resuscitation with lipids in patients with cardiac arrest following regional anesthesia. Early treatment with lipidic emulsion of patients with neurological symptoms can prevent cardiac arrest or quicken the return of spontaneous heartbeat. When faced with a patient with signs of severe toxicity due to local anesthetics (unconsciousness, tonic-clonic convulsions, cardiovascular collapse, the following steps must be taken: suspend local anesthetic injection, request help, keep respiratory ducts permeable, supply oxygen at 100 per cent, maintain adequate pulmonary ventilation, control convulsions (benzodiazepine, tiopenthal or propofol in incremental doses), begin cardiopulmonary reanimation, intravenous bolus of Intralipid@ 20 per cent, 1,5 ml/kg in 1 minute, continue CPR and repeat bolus twice at 5 minute intervals if adequate circulation has not been restores. After 5 minutes, increase the rate of infusion to 0,5 ml/kg.min, continue infusion of lipidic emulsion until adequate circulation has be en achieved and continue CPR thraughout the treatment with lipidic emulsion...
A toxicidade sistêmica causada por superdose de anestésico local é uma complicação rara, mas potencialmente devastadora, da anestesia regional e central neuroaxial. O colapso cardiovascular que segue à toxicidade sistêmica por superdose de anestésico local, especialmente a bupivacaína, é extremamente difícil de tratar usando os fármacos padrões de ressuscitação; o resultado potencial é uma parada cardíaca refratária a esta ação. A emulsão lipídica pode restaurar rapidamente a circulação depois de um colapso cardiovascular induzido por anestésicos locais. Modelos experimentais de toxicidade por anestésicos locais mostraram rápida recuperação da função cardíaca espontânea após infusão lipídica, tanto em animais intactos como em corações isolados. Diversos relatórios de caso referidos à extensão destes achados à área clínica citam o uso de lipídeos para a rápida ressuscitação de pacientes com parada cardíaca causada por anestesia regional. O tratamento precoce com emulsão lipídica de pacientes com sinais neurológicas pode prevenir a parada cardíaca ou acelerar o retorno do batimento cardíaco espontâneo. Quando um indivíduo apresenta sintomas de grave toxicidade por anestésico local (inconsciência, convulsões tônico-clônicas, colapso cardiovascular), é necessário suspender a injeção de anestésico local, pedir ajuda, manter a via aérea permeável, administrar oxigênio a 100 por cento, manter uma adequada ventilação pulmonar, controlar as convulsões (benzodiazepinas, tiopental ou propofol em doses incrementais), começar a reanimação cardiopulmonar, administrar bolo intravenoso de Intralipid® 20 por cento, 1,5 ml/kg em 1 minuto, continuar RCP, iniciar infusao intravenosa de Intralipid® 20 por cento, 0,25 ml/kg.min, continuar RCP e repetir duas vezes o bolo, em intervalos de 5 minutos, se nao for restaurada uma adequada circulação...