Amrinone is superior to epinephrine in reversing bupivacaine-induced cardiovascular depression in sevoflurane-anesthetized dogs

Dibucaine toxicosis in a dog

INTRODUCTION

Dibucaine is a potent, long-lasting local anesthetic (LA). Topical dibucaine ointments are marketed directly to consumers in the USA without prescription. Dibucaine ointment is intended to treat discomfort associated with sunburn, eczema, minor rashes, minor scratches, insect bites, and poison ivy and is used alone or in combination with other active ingredients to treat pain associated with hemorrhoids or other anorectal disorders. Oral dibucaine toxicosis has been reported in children and includes gastrointestinal upset and neurologic and cardiovascular dysfunction.

CASE REPORT

An 18-month-old, female, Parson Russell terrier ingested approximately 23 g of 1% dibucaine ointment (approximately 38 mg/kg dibucaine) recommended to the owner for the treatment of hemorrhoids. Onset and resolution of clinical signs were relatively rapid, 5 min and 60 min, respectively. Clinical signs included vomiting, ptyalism, whole-body muscle fasciculations, disorientation, and severe ataxia.

DISCUSSION

Oral dibucaine toxicosis in dogs is similar to oral dibucaine toxicosis in children. Dibucaine ointment poses a real and potentially serious toxicological risk to pets and thus should be stored in a safe location.

The Effect of Insulin on the Resuscitation of Bupivacaine-Induced Severe Cardiovascular Toxicity in Dogs

Resuscitation after bupivacaine-induced cardiovascular collapse is difficult and often resistant to conventional treatment. We tested the hypothesis that insulin treatment would effectively reverse bupivacaine-induced cardiovascular collapse in pentobarbital-anesthetized dogs. Bupivacaine was administered at 0.5 mg. kg(-1). min(-1) until mean arterial blood pressure decreased to 40 mm Hg or less. In the insulin-glucose-potassium (IGK) group (n = 7), an IV bolus of regular insulin (2 U/kg) was given, followed by a glucose infusion (2 mL/kg of 50% dextrose in water) for 30 min and a potassium infusion (1-2 mmol. kg(-1). h(-1)). In the control group (n = 7), glucose infusion was given as in the IGK group. In contrast to the control group, all IGK dogs survived. Mean arterial blood pressure, heart rate, cardiac output, mixed venous oxygen saturation, and end tidal CO(2) recovered toward baseline levels in the IGK group. In conclusion, severe bupivacaine-induced cardiovascular collapse in dogs was effectively reversed with the insulin treatment.

A comparison of epinephrine and vasopressin in a porcine model of cardiac arrest after rapid intravenous injection of bupivacaine

In a porcine model, we compared the efficacy of epinephrine, vasopressin, or the combination of epinephrine and vasopressin with that of saline placebo on the survival rate after bupivacaine-induced cardiac arrest. After the administration of 5 mg/kg of a 0.5% bupivacaine solution i.v., ventilation was interrupted for 3 +/- 1 min (mean +/- SD) until asystole occurred. Cardiopulmonary resuscitation (CPR) was initiated after 1 min of cardiac arrest. After 2 min of CPR, 28 animals received, every 5 min, epinephrine; vasopressin; epinephrine combined with vasopressin; or placebo i.v.. Three minutes after each drug administration, up to 3 countershocks (3, 4, and 6 J/kg) were administered; all subsequent shocks were 6 J/kg. Blood was drawn throughout the experiment for the determination of plasma bupivacaine concentration. In the vasopressin/epinephrine combination group, all pigs survived (P < 0.01 versus placebo); in the vasopressin group 5 of 7, in the epinephrine group 4 of 7, and in the placebo group none of 7 swine survived. The plasma concentration of total bupivacaine showed no significant difference among groups. In this model of bupivacaine-induced cardiac arrest, CPR with a combination of vasopressin and epinephrine resulted in significantly better survival rates than in the placebo group.

IMPLICATIONS

Although cardiovascular collapse occurs mostly immediately after rapid injection of a local anesthetic in the presence of anesthesiologists, resuscitation may be difficult, and the outcome is usually poor. In this model of bupivacaine-induced cardiac arrest, cardiopulmonary resuscitation with a combination of vasopressin and epinephrine resulted in significantly better survival rates than in the placebo group.

The efficacy of nicorandil, calcium chloride and nitroglycerin in treatment of ropivacaine-induced cardiotoxicity

BACKGROUND AND OBJECTIVE

The amide-linked local anaesthetics, bupivacaine and ropivacaine, can cause depression of cardiac contractility and dysrhythmias. In a previous study, we observed decreased contractility and ST segment depression following ropivacaine administration in anaesthetized dogs. The efficacy of intravenous (i.v.) and intracoronary nicorandil (30 and 100 microg kg(-1)), i.v. nitroglycerin (glyceryl trinitrate) (5 microg kg(-1)) and calcium chloride (1, 2 and 4 mmol) in reversing the cardiotoxic effects of intracoronary ropivacaine were studied following the administration of intracoronary ropivacaine.

METHODS

Six dogs were studied. The dogs were anaesthetized with i.v. pentobarbital (30 mg kg(-1)). A left-sided thoracotomy was performed and the left circumflex coronary was cannulated. For each dog, the dose of ropivacaine was identified, which produced measurable cardiotoxicity. In each case, ropivacaine was followed by one of the three resuscitation drugs. The effects of each resuscitation drug on ST segments and left ventricular contractility (dP/dt) produced by ropivacaine alone were compared with those produced by ropivacaine followed by each of the three resuscitation drugs using Fisher's exact test.

RESULTS

The doses of ropivacaine required to produce depression of left ventricular dP/dt and ST segments ranged from 1 to 8 mg. Ropivacaine-induced depression of left ventricular contractility (dP/dt) was more rapidly and completely reversed by calcium chloride than by either nitroglycerin or nicorandil (P = 0.008).

CONCLUSIONS

Calcium chloride may be effective in the treatment of inadvertent intravascular administration of amide local anaesthetic agents.

Continuous mixed venous oxygen saturation, not mean blood pressure, is associated with early bupivacaine cardiotoxicity in dogs

PURPOSE

To investigate changes of continuous mixed venous oxygen saturation (cSvO(2)) and mean arterial blood pressure (MBP) in dogs with bupivacaine-induced cardiac depression.

METHODS

Bupivacaine was infused into pentobarbital-anesthetized mongrel dogs (n = 8) at a rate of 0.5 mg.kg(-1).min(-1) until the MBP was 40 mmHg or less (end of bupivacaine infusion; BIE). The infusion time was divided into the early period, first 30 min of bupivacaine infusion and the late period, which was from 30 min of bupivacaine infusion until BIE. cSvO(2) was monitored using a fibreoptic pulmonary artery catheter, and MBP and cardiac output (CO) were measured every ten minutes after the initiation of bupivacaine infusion. Arterial blood gas, serum electrolyte and bupivacaine concentration were measured simultaneously. The relationships between CO and cSvO(2), and of CO vs MBP were compared by regression analysis in the early and late periods.

RESULTS

The Pearson's correlation coefficients between CO and cSvO(2) were 0.782 (P = 2.1 x 10(-7)) in the early period and 0.824 (P = 1.3 x 10(-6)) in the late period. The correlation coefficients between CO and MBP were 0.019 (P = 0.921) in the early period and 0.799 (P = 4.8 x 10(-6)) in the late period.

CONCLUSIONS

cSvO(2), but not MBP, is associated with CO changes in bupivacaine-induced cardiac depression during the early period of bupivacaine intoxication. Decrease of MBP with low cSvO(2) observed during the late period might imply severe cardiac depression induced by bupivacaine infusion.

Comparison of the effects of amrinone, milrinone and olprinone in reversing bupivacaine-induced cardiovascular depression

BACKGROUND

Increasing evidence indicates that amrinone, a phosphodiesterase fraction III (PDE-III) inhibitor, has relative efficacy as an initial treatment for cardiovascular depression after bupivacaine in an experimental setting. This study was performed to compare the cardiovascular effects of the other new PDE-III inhibitors, milrinone and olprinone, with those of amrinone in reversing bupivacaine-induced cardiovascular depression.

METHODS

In sevoflurane-anaesthetized dogs, bupivacaine was infused intravenously at 1 mg x kg(-1) x min(-1) until mean arterial pressure fell to 60 mmHg or less. The dogs received either amrinone (2 mg x kg(-1)), milrinone (0.2 mg x kg(-1)), olprinone (0.12 mg x kg(-1)) or 0.9% saline (0.5 ml x kg(-1)).

RESULTS

Amrinone, milrinone and olprinone improved left ventricular systolic and diastolic function, resulting in an increase in cardiac index. The most significant difference observed among the three drugs was the change in heart rate (HR) after treatment. Milrinone significantly increased HR, but olprinone did not.

CONCLUSION

Milrinone and olprinone are as effective as amrinone in reversing bupivacaine-induced cardiovascular depression.

Dose-related cardiovascular effects of amrinone and epinephrine in reversing bupivacaine-induced cardiovascular depression

BACKGROUND

To ascertain the efficacy of amrinone and epinephrine in reversing bupivacaine-induced cardiovascular depression, we investigated the time course of recovery of cardiac function with 3 doses of both agents after bupivacaine administration.

METHODS

In sevoflurane-anaesthetized dogs, bupivacaine was infused intravenously at 1 mg.kg-1.min-1 until mean arterial pressure fell to 60 mmHg or less. The 3 doses of amrinone (1, 2, and 4 mg.kg-1) or the 3 doses of epinephrine (2, 5, and 10 micrograms.kg-1) were administered as a bolus in randomized order in each dog.

RESULTS

Amrinone improved maximum left ventricular dP/dt, a time constant of left ventricular isovolemic relaxation and cardiac index persistently and dose-relatedly. Amrinone increased heart rate and decreased left ventricular end-diastolic pressure and systemic vascular resistance index. Amrinone at 1 and 2 mg.kg-1 significantly increased mean arterial pressure, but amrinone at 4 mg.kg-1 did not. Epinephrine increased mean arterial pressure, maximum left ventricular dP/dt, and systemic vascular resistance dose-relatedly. The duration of action of epinephrine, peaking at 1 min and subsequently decreasing by 10 min after administration, did not differ among the groups. Epinephrine at all doses failed to improve a time constant of left ventricular isovolemic relaxation and cardiac index. ECG evidence of serious ventricular dysrhythmias was seen in 1 out of 6 dogs after administrating each dose of amrinone and in 3, 3 and 5 out of 6 dogs after administrating 2, 5 and 10 micrograms.kg-1 of epinephrine, respectively.

CONCLUSION

Bolus amrinone may have a certain efficacy in reversing bupivacaine-induced cardiovascular depression, and improving cardiac contractility and relaxation dose-relatedly. In contrast to amrinone, bolus epinephrine remains indispensable for resuscitation, causing a rapid, massive, transient and dose-related rise in blood pressure. However, the use of amrinone may be limited predominantly by a decrease in systemic vascular resistance, while the use of epinephrine may be limited predominantly by the generation of serious ventricular dysrhythmias and lack of effectiveness on cardiac index and on cardiac relaxation.

Structure-affinity relationships and stereospecificity of several homologous series of local anesthetics for the beta2-adrenergic receptor

Local anesthetics inhibit binding of ligands to beta2-adrenergic receptors (beta2ARs), and, as a consequence, inhibit intracellular cAMP production. We hypothesized that among homologous local anesthetics, their avidity at inhibiting binding of tritiated dihydroalprenolol (3H-DHA) to beta2ARs would increase with increasing length of alkyl substituents and would demonstrate stereospecificity. Specific binding of 3H-DHA to human beta2ARs was assayed in the presence of six different members of the 1-alkyl-2,6-pipecoloxylidide class of local anesthetics (including mepivacaine, ropivacaine, and bupivacaine), the R(+) and S(-) bupivacaine enantiomers, lidocaine, prilocaine, etidocaine, procaine, and tetracaine. Avidity of binding to beta2ARs increased with increasing length of the alkyl chain (pKi values = 2.4, 3.6, 4.3, 4.1, 4.1, 5.9 for the methyl [mepivacaine], ethyl, S(-)propyl [ropivacaine], butyl [bupivacaine], pentyl, and octyl derivatives, respectively). We found no evidence for bupivacaine stereospecificity (pKi values = 4.3 and 4.9 for the S(-) and R(+) isomers, respectively). Other amide and ester local anesthetics also showed increasing potency with increasing length of alkyl substituents (pKi values = 3.6, 3.8, and 4.3 for lidocaine, prilocaine, and etidocaine; 4.2 and 5.6 for procaine and tetracaine, respectively). The correlation between increased inhibition of beta2AR binding and alkyl chain length resembles the correlation between local anesthetic potency at nerve block and increased alkyl chain length. The lack of clear stereospecificity is consistent with the relatively low potency these agents demonstrate at inhibition of beta2AR binding. Finally, the relatively potent inhibition of beta2ARs by etidocaine, tetracaine, and bupivacaine suggests that their propensity for cardiovascular depression after accidental intravenous overdose could result from beta2AR or beta1AR blockade and inhibition of cAMP production.

IMPLICATIONS

Local anesthetics demonstrate a rank order of avidity for displacing ligands from beta2-adrenergic receptors such that larger molecules displace ligands at lower concentrations than smaller local anesthetic molecules. This relationship between molecular size and receptor avidity could explain the greater propensity for cardiovascular toxicity of relatively large local anesthetics such as bupivacaine.

Comparative electrophysiologic and hemodynamic effects of several amide local anesthetic drugs in anesthetized dogs

Large and equipotent doses of several local anesthetics were administered in a cardiac electrophysiologic model on closed-chest dogs. Five groups of pentobarbital-anesthetized dogs were each given intravenously 16 mg/kg lidocaine, 12 mg/kg mepivacaine, 4 mg/kg or 8 mg/kg etidocaine, and 4 mg/kg bupivacaine. Lidocaine induced bradycardia, slowing of atrioventricular node conduction (AH), and marked hemodynamic depression, represented by a decrease in mean aortic pressure (MAoP), in the peak of first derivative of left ventricular pressure (LVdP/dt(max)) and by an increase in left ventricular end-diastolic pressure (LVEDP). Atrial pacing at pacing cycle length (PCL) of 298 ms did not enhance the alteration of variables of ventricular conduction (His ventricle [HV] interval and QRS duration). Mepivacaine induced slight alteration of electrophysiologic variables. Atrial pacing at PCL of 312 ms did not enhance the alteration of HV and QRS duration. Mepivacaine induced transient hemodynamic depression. Etidocaine (4 mg/kg) induced electrophysiologic and hemodynamic alterations similar to mepivacaine but artrial pacing at PCL of 330 ms enhanced HV lengthening and QRS widening (P < 0.05). Etidocaine (8 mg/kg) induced marked impairment of PR, HV, QRS, and QT, and dramatic hemodynamic depression represented by a decrease in MAoP from 123.5 +/- 16.2 at baseline to 36.5 +/- 8.3 mm Hg at 1 min (P < 0.001) and of LVdP/dtmax) from 1446 +/- 379 to 333 +/- 93 mm Hg/s (P < 0.001). Bupivacaine induced dramatic impairment of electrophysiologic variables. Bupivacaine also decreased LVDP/dtmax (from 1333 +/- 347 to 617 +/- 299,P < 0.001) and increased LVEDP. We conclude that mepivacaine induced moderate cardiotoxicity. In contrast, lidocaine induced dramatic hemodynamic depression while etidocaine and bupivacaine markedly impaired both electrophysiologic and hemodynamic variables. This double impairment could explain the great difficulty in resuscitating patients who have had cardiotoxic accidents induced by etidocaine or bupivacaine.