Hemodynamic effects of ropivacaine and levobupivacaine intravenous injection in swines

Two fatal and four surviving cases after accidental infusion of ropivacaine

Purpose

In this paper, we describe six cases, where patients were falsely treated with pre-filled ropivacaine solution instead of medical saline solution for postoperative settings. Two of the patients died because of fatal concentrations of ropivacaine in blood, four survived with no further physical injury, and two of them showed typical intoxication symptoms. The collected blood and urine samples of the deceased, as well as the surviving patients, were analyzed in laboratory routine screening.

Methods

Ropivacaine and its main metabolite 3-OH-ropivacaine were analyzed by gas chromatography–mass spectrometry.

Results

All of the six cases showed positive blood results of ropivacaine. Due to the poorly secured sample material of the survived patients at hospital, the quantitative examination of 3-OH-ropivacaine could not be carried out. In one fatal case, there were ropivacaine and 3-OH-ropivacaine traceable in urine. In all cases, metamizole was found in blood and traces of piritramide in urine. The amount of metamizole was within the upper limits of therapeutical treatment values. Patients with lower blood concentrations of ropivacaine showed more physical symptoms as compared to those with higher concentrations of active substances.

Conclusions

In the context of symptom development and intoxication, the speed of injection was a very important factor to cause fatal ropivacaine cases. To our knowledge, these are the first reported cases of fatal intoxication with ropivacaine.

Intravenous Lipid Emulsion for Levobupivacaine Intoxication in Acidotic and Hypoxaemic Pigs

Intravenous lipid emulsion is, in some countries, the recommended treatment for local anaesthetic toxicity. Systemic local anaesthetic toxicity results in hypoxaemia and acidosis, and whether this influences the effects of lipid therapy on drug concentrations and cardiovascular recovery is currently unknown. Twenty anaesthetised pigs were given a 3 mg/kg bolus of levobupivacaine followed by a five-minute phase of hypoventilation and 1 mmol/kg of lactic acid over one minute. After lactic acid infusion, pigs were treated, in randomised order, with either 20% lipid emulsion or Ringer's acetate for 30 minutes: a 1.5 ml/kg bolus followed by a 0.25 ml/kg/minute infusion. Haemodynamic parameters were recorded and blood samples were collected for pharmacokinetic analysis. There was no difference between the groups in the area under the plasma levobupivacaine concentration–time curve (AUC) or between that and AUC of unentrapped levobupivacaine in the Lipid group, or in the plasma half-lives. The cardiovascular outcome and normalisation of the electrocardiogram were similar in both groups. Five pigs developed marked hypotension: one in both groups died, while two in the Lipid group and one in the Ringer group needed adrenaline. Administration of lipid emulsion did not improve cardiovascular recovery from levobupivacaine toxicity exacerbated by acidosis and hypoxaemia. Lipid emulsion did not entrap levobupivacaine or affect levobupivacaine pharmacokinetics.

Electrocardiographic and blood pressure alterations caused by intravenous injection of ropivacaine - a study in piglets

OBJECTIVES

Objective signs to detect inadvertent intravascular injection of local anesthetics are essential in the anesthetized pediatric patient. For early detection of intravenous bupivacaine administration, it was shown that an epinephrine containing test dose reliably provoked T-wave alterations, changes in heart rate (HR) and blood pressure, whereas intravenous injection of plain bupivacaine could not be detected until high doses were applied. This study investigates electrocardiographic and hemodynamic alterations caused by intravenous ropivacaine.

METHODS

Twenty-four piglets, anesthetized with sevoflurane, were randomized into two groups: Group R received as test dose plain ropivacaine 0.2% and group RE, ropivacaine 0.2% + epinephrine 5 μg·ml(-1) . Under stable conditions, 0.2 ml kg(-1) of the test solution was intravenously injected. Twenty minutes later, 0.4 ml kg(-1) was applied. A positive effect was defined as HR increase ≥ 10 bpm, increase in mean arterial pressure (MAP) ≥ 15 mmHg, T-wave increase ≥ 25% baseline. In another setting ropivacaine was intravenously infused until cardiac arrest.

RESULTS

After injection of 0.2 or 0.4 ml kg(-1) test solution, a positive increase in HR and MAP was found in 0% of group R and in 100% of group RE. An increase in T-wave ≥ 25% was found in 42% of group R and in 100% of group RE. During intoxication, T-elevation was seen in 83%.

CONCLUSIONS

An epinephrine containing test dose ropivacaine reliably provoked T-wave elevations and increases in HR and MAP. A small dose plain ropivacaine caused T-elevations in a remarkable percentage, whereas higher, quite toxic doses provoked T-elevations in most of the pigs.

Lipídeos nas intoxicações por anestésicos locais

INTRODUÇÃO: Com o advento dos anestésicos locais de longa duração, a anestesia locorregional ganhou grande impulso sendo cada vez mais utilizada. Novas técnicas de bloqueios foram descritas e a técnica é frequentemente associada à anestesia geral com o objetivo de proporcionar analgesia pós-operatória. A contra-partida é a necessidade da utilização de grandes doses com risco de acidentes por injeção intravascular inadvertida; trata-se de complicação grave sem tratamento específico até há alguns anos. Em 1998 foi proposta a utilização de emulsões lipídicas em animais e a partir de 2006 vários trabalhos demonstraram o interesse dessas soluções nos casos de intoxicações por anestésicos locais com diminuição da morbi-mortalidade. O objetivo desta revisão foi fazer um levantamento da metodologia, revisando os mecanismos, interesses, limites e as condutas preconizadas atualmente. MÉTODO: Foram revistas algumas referências históricas sobre anestésicos locais, artigos publicados nos últimos 30 anos em revistas indexadas no Medline e em dois livros-texto. Foram selecionados os artigos que tratavam da intoxicação por anestésicos locais, da terapia com emulsões lipídicas, os de revisão sobre o assunto e as condutas adotadas em diversos serviços e países, sendo realizada uma síntese. CONCLUSÕES: A eficiência e interesse da terapia com emulsões lipídicas nas intoxicações por anestésicos locais não é mais a demonstrar; várias sociedades da especialidade já publicaram suas diretrizes e aconselham que se disponha desses produtos nos locais onde se pratica a anestesia locorregional.

Midazolam in rabbits terminates dysrhythmias caused by intracerebroventricular ropivacaine

The current study was designed to investigate the mechanisms by which ropivacaine may act within the central nervous system (CNS) to produce cardiotoxicity. Eighty New Zealand rabbits were divided into four groups randomly. In Group 1, 20 rabbits received intracerebroventricular (icv) saline, and then received icv ropivacaine 30 min later. In Group 2, 20 rabbits received icv ropivacaine. Whenever dysrhythmias continued for more than 5 min, 0.1 ml saline was administered into the left cerebral ventricle. Ten minutes later, 0.1 ml midazolam was given into the left lateral ventricle. In Group 3, 20 rabbits received icv ropivacaine, and once the dysrhythmias developed, the inspired isoflurane concentration was increased from 0.75% to 1.50%. In Group 4, 20 animals received an intravenous (iv) phenylephrine infusion until dysrhythmias occurred. In Group 1, the rabbits did not develop dysrhythmias in response to icv saline, whereas dysrhythmias did develop in these animals after icv ropivacaine. In Group 2, icv saline had no effect on the dysrhythmias; however, icv midazolam terminated cardiac dysrhythmias. In Group 3, an increase in the concentration of the inspired isoflurane had no effect on dysrhythmias. In Group 4, icv midazolam had no effect on dysrhythmias in response to iv phenylephrine. Ropivacaine administered directly into the CNS is capable of producing cardiac dysrhythmias; midazolam terminated dysrhythmias presumably by potentiation of γ-aminobutyric acid (GABA) receptor activity. Our results suggest that ropivacaine produces some of its cardiotoxicity not only by the direct cardiotoxicity of the drug, but also by the CNS effects of ropivacaine.