Epinephrine Injection in Lipid-Based Resuscitation from Bupivacaine-Induced Cardiac Arrest

Levosimendan combined with epinephrine improves rescue outcomes in a rat model of lipid-based resuscitation from bupivacaine-induced cardiac arrest

Background

The effectiveness of a combination of a lipid emulsion with epinephrine in reversing local anesthetic-induced cardiac arrest has been confirmed. The combination of a lipid emulsion with levosimendan, was shown to be superior to administration of a lipid emulsion alone with regard to successful resuscitation. In this study, we compared the reversal effects of levosimendan, epinephrine, and a combination of the two agents in lipid-based resuscitation in a rat model of bupivacaine-induced cardiac arrest.

Methods

Fifty-four adult male Sprague-Dawley rats were subjected to bupivacaine (15 mg·kg⁻¹) –induced asystole and were then randomly divided into 3 groups. A lipid emulsion was used as the basic treatment, and administration of drug combinations varied in each group as follows: (1) levosimendan combined with epinephrine (LiEL); (2) epinephrine (LiE); and (3) levosimendan (LiL). The resuscitation outcomes were recorded and included the rate of return of spontaneous circulation (ROSC) and survival at 40 min, time to first heartbeat, time to ROSC, and cumulative dose of epinephrine. We calculated the wet-to-dry ratio of the lung, blood gas values at 40 min and bupivacaine concentration of cardiac tissue and plasma.

Results

The rates of ROSC in LiEL and LiE groups were higher than LiL group (P < 0.001; LiEL vs LiL, P = 0.001; LiE vs LiL, P = 0.007). The survival rate in LiEL group was higher than LiE group (P = 0.003; LiEL vs LiE, P = 0.008; LiEL vs LiL, P = 0.001). The time to first heart beat in LiEL group was shorter than LiE, LiL groups. (P < 0.001; LiE vs LiEL, P = 0.001; LiL vs LiEL, P < 0.001). The time to ROSC in LiEL group was shorter than LiE, LiL groups (P < 0.001; LiEL vs LiE, P < 0.001; LiEL vs LiL, P < 0.001). The result was similar for the bupivacaine concentration of cardiac tissue and plasma (cardiac tissue: P = 0.002; plasma: P = 0.011). Furthermore, there were significant differences in the blood-gas values at 40 min, wet-to-dry lung weight ratio, and ratio of damaged alveoli among groups. The LiEL group had the best result for all parameters (P < 0.01, P = 0.008, P < 0.001, respectively). Additionally, significantly less epinephrine was used in the LiEL group (P < 0.001).

Conclusions

Levosimendan combined with epinephrine may be superior to either drug alone for lipid-based resuscitation in a rat model of bupivacaine-induced cardiac arrest. The drug combination was associated with a higher survival rate as well as decreased epinephrine consumption and lung damage.

Giving Priority to Lipid Administration Can Reduce Lung Injury Caused by Epinephrine in Bupivacaine-Induced Cardiac Depression

BACKGROUND AND OBJECTIVES

Epinephrine is usually administered in concert with a lipid emulsion during local anesthetic toxicity. However, the timing and role of epinephrine administration in combination with a lipid emulsion remain unclear. Specifically, the temporal association of epinephrine and lipid emulsion administration with related changes in pulmonary vascular pressures that may lead to pulmonary edema and hemorrhage needs to be determined.

METHODS

This study consisted of 2 parts, experiments A and B. In experiment A, 24 adult male Sprague-Dawley rats were randomly divided into 3 groups (n = 8) to receive 1 of 3 treatments. All rats were anesthetized with an intraperitoneal injection of chloral hydrate, and anesthesia was maintained by sevoflurane. Each treatment group was initially given an infusion of bupivacaine (15 mg/kg) in order to produce cardiac depression. Group 1 (A-LEN) received a 30% lipid infusion (3 mL/kg) followed by a rapid epinephrine bolus (10 μg/kg), which was then followed by a normal saline infusion (3 mL/kg). Group 2 (A-NEL) first received a normal saline infusion (3 mL/kg) followed by a rapid epinephrine bolus, which was then followed by a 30% lipid emulsion. Group 3 (A-NEN, considered a control group) first received a normal saline infusion (3 mL/kg) followed by a rapid epinephrine bolus (10 μg/kg), which was then followed by another normal saline infusion (3 mL/kg). Lipid and normal saline infusions were administered over 1 minute, whereas epinephrine was injected rapidly. The continuous monitoring of blood pressure, heart rate, pulmonary arterial pressure, and pulmonary venous pressure occurred for 30 minutes. After the 30-minute monitoring period, lung tissue was sampled, and bronchoalveolar lavage fluid was collected. In experiment B, the experimental model and resuscitation protocol were similar to experiment A (B-LEN and B-NEL groups). In this arm of the experiment, bupivacaine concentrations of cardiac tissue were determined after the second minute of normal saline infusion.

RESULTS

The A-LEN group produced the best rate pressure product when compared with the A-NEL or A-NEN group (P = 0.045, P = 0.011, respectively). In regard to pulmonary venous pressure, the A-LEN group was lower than the A-NEL or A-NEN group (P = 0.031, P = 0.006, respectively). Animals in the A-NEL and A-NEN groups rapidly developed pulmonary edema after infusion of epinephrine. The wet-to-dry ratio of the lungs in the A-LEN group was lower than that of the lungs in the A-NEL group (P = 0.024).The lung permeability index of the A-LEN group was lower than that of the A-NEL group (P = 0.011). In experiment B, concentrations of bupivacaine in cardiac tissue and plasma of the B-LEN group were lower than those of the B-NEL group (P = 0.001, P = 0.03, respectively).

CONCLUSIONS

Giving priority to the administration of a lipid emulsion before the administration of epinephrine can reduce lung injury in bupivacaine-induced cardiac depression in rats.

Intravenous Lipid Emulsion for Management of Systemic Toxic Effects of Drugs

The incidence of toxic effects of drugs leading to emergency department visits has increased in the United States in the past several years. Most of these patients can be adequately managed by supportive care alone. However, pharmacological antidotes may be necessary, particularly in patients with hemodynamic instability. In severe cases refractory to conventional antidote therapy, rescue therapy with intravenous lipid emulsion (ILE) may be necessary. Traditionally, ILE has been used as an antidote of choice in treating toxic effects of local anesthetics. But data continue to emerge on the successful use of ILE to treat overdoses of drugs other than local anesthetics, particularly lipophilic medications. The recommended ILE dose is a 1.5 mL/kg bolus followed by infusion of 15 mL/kg per hour, with repeat dosing permissible for continued hemodynamic instability. Use of ILE should be considered early as a rescue therapy in the settings of lipophilic medication overdoses when cardiovascular compromise or cardiac arrest is present.

Systematic review of the effect of intravenous lipid emulsion therapy for local anesthetic toxicity

BACKGROUND

Following national and regional recommendations, intravenous lipid emulsion (ILE) has become established in clinical practice as a treatment for acute local anesthetic (LA) toxicity, although evidence of efficacy is limited to animal studies and human case reports. A collaborative lipid emulsion workgroup was therefore established by the American Academy of Clinical Toxicology to review the evidence on the effect of ILE for LA toxicity.

METHODS

We performed a systematic review of the literature published through 15 December 2014. Relevant articles were determined based on pre-defined inclusion and exclusion criteria. Pre-treatment experiments, pharmacokinetic studies not involving toxicity and studies that did not address antidotal use of ILE were excluded.

RESULTS

We included 113 studies and reports. Of these, 76 were human and 38 animal studies. One publication included both a human case report and an animal study. Human studies included one randomized controlled crossover trial involving 16 healthy volunteers. The subclinical LA toxicity design did not show a difference in the effects of ILE versus saline. There was one case series and 73 case reports of ILE use in the context of toxicity (83 patients) including CNS depression or agitation (n = 45, 54%), seizures (n = 49, 59%), hypotension, hypertension, EKG changes, arrhythmias (n = 39, 47%), cardiac arrest (n = 18, 22%), cardiopulmonary resuscitation, and/or requirement for endotracheal intubation and/or mechanical ventilation (n = 35, 42%). There were 81 (98%) survivors including 63 (76%) with no reported sequelae from the LA poisoning or ILE, although the presence or absence of sequelae was not reported in 15 (18%) cases. Animal studies included 29 randomized controlled studies, three observational studies, five case series, and one case report; bupivacaine was used in 29 of these reports (76%). Of 14 controlled experiments in animals, eight showed improved survival or time to return of spontaneous circulation and five no benefit of ILE versus saline or non-ILE treatments. Combining ILE with epinephrine improved survival in five of the six controlled animal experiments that studied this intervention. The studies were heterogeneous in the formulations and doses of ILE used as well as the doses of LA. The body of the literature identified by this systematic review yielded only a very low quality of evidence.

CONCLUSION

ILE appears to be effective for reversal of cardiovascular or neurological features in some cases of LA toxicity, but there is currently no convincing evidence showing that ILE is more effective than vasopressors or to indicate which treatment should be instituted as first line therapy in severe LA toxicity.

Epinephrine reversed high-concentration bupivacaine- induced inhibition of calcium channels and transient outward potassium current channels, but not on sodium channel in ventricular myocytes of rats

Background

Epinephrine is a first-line drug for cardiopulmonary resuscitation, but its efficacy in the treatment of bupivacaine-induced cardiac toxicity is still in question. We hypothesized that epinephrine can reverse cardiac inhibition of bupivacaine by modulating ion flows through the ventricular myocyte membrane channels of rats. The aim of this study was to observe and report the effects of epinephrine on high-concentration bupivacaine-induced inhibition of sodium (I_Na), L-type calcium (I_Ca-L), and transient outward potassium (I_to) currents in the ventricular myocytes of rats.

Methods

The ventricular myocytes were isolated from Sprague-Dawley rats (250-300 g) by acute enzymatic dissociation. The whole-cell patch clamp technique was used to record the ion channel currents in single ventricular myocytes both before and after administration of medications.

Result

Administration of bupivacaine 100 μmol/L significantly reduced I_Na, (P < 0.05). However, administration of bupivacaine 100 μmol/L in conjunction with epinephrine 0.15 μg/ml had no effect in restoring I_Na to its previous state. Similarly, a sharp decline of I_Ca-L and I_to was observed after administration of bupivacaine 100 μmol/L (P < 0.05). In contrast to I_Na, I_Ca-L and I_to were significantly improved after the administration of the aforementioned combination of bupivacaine and epinephrine (P < 0.05).

Conclusion

Epinephrine can reverse high-concentration bupivacaine induced inhibition of I_Ca-L and I_to, but not I_Na. Thus, epinephrine’s effectiveness in reversal of bupivacaine-induced cardiac toxicity secondary to sodium channel inhibition may be limited.

The effect of fat emulsion on hemodynamics following treatment with propranolol and clonidine in anesthetized rats

OBJECTIVES

There is evidence indicating that intravenous fatty emulsion (IFE) is beneficial in restoring circulatory function in certain types of drug overdose. The authors investigated the hemodynamic effects of IFE compared to epinephrine in rats treated with propranolol and clonidine.

METHODS

Anesthetized male Sprague-Dawley rats were instrumented for measurement of hemodynamics. Rats were randomly assigned to one of six groups (n = 6-8), and each received a clonidine infusion (150 μg/kg) or an equivalent volume of normal saline (0.9% NaCl) over 1 hour. Each rat then received normal saline (1.0 mL/kg) or propranolol (15 to 20 mg/kg). Thereafter, each rat received a dose of IFE (20% solution; 1.0 mL/kg) or epinephrine (2.0 μg/kg) or an equivalent volume of normal saline (1.0 mL/kg).

RESULTS

Propranolol alone or with clonidine significantly (p < 0.05) reduced a number of hemodynamic parameters (mean arterial pressure, 37% to 70%; heart rate, 30% to 51%; cardiac contractility [dP/dtmax], 50% to 67%; and abdominal aortic blood flow, 50% to 83%), while increasing PR intervals (65% to 85%) and QTc intervals (26% to 64%). Saline and epinephrine treatment after propranolol and clonidine combined resulted in no survivors in saline and two out of six in epinephrine group. IFE resulted in significant survival (seven out of eight) for 30 minutes in rats treated with propranolol alone, and propranolol combined with clonidine (seven out of eight).

CONCLUSIONS

These data demonstrate that IFE is effective for resuscitating rats overdosed on propranolol combined with clonidine. The effect of IFF is unlikely due to a direct positive inotropic or chronotropic action on the myocardium. IFE is also more effective than epinephrine treatment in this paradigm.

Resuscitation with lipid emulsion: dose-dependent recovery from cardiac pharmacotoxicity requires a cardiotonic effect

BACKGROUND

Recent publications have questioned the validity of the "lipid sink" theory of lipid resuscitation while others have identified sink-independent effects and posed alternative mechanisms such as hemodilution. To address these issues, the authors tested the dose-dependent response to intravenous lipid emulsion during reversal of bupivacaine-induced cardiovascular toxicity in vivo. Subsequently, the authors modeled the relative contribution of volume resuscitation, drug sequestration, inotropy and combined drug sequestration, and inotropy to this response with the use of an in silico model.

METHODS

Rats were surgically prepared to monitor cardiovascular metrics and deliver drugs. After catheterization and instrumentation, animals received a nonlethal dose of bupivacaine to produce transient cardiovascular toxicity, then were randomized to receive one of the four treatments: 30% intravenous lipid emulsion, 20% intravenous lipid emulsion, intravenous saline, or no treatment (n = 7 per condition; 28 total animals). Recovery responses were compared with the predictions of a pharmacokinetic-pharmacodynamic model parameterized using previously published laboratory data.

RESULTS

Rats treated with lipid emulsions recovered faster than did rats treated with saline or no treatment. Intravenous lipid emulsion of 30% elicited the fastest hemodynamic recovery followed in order by 20% intravenous lipid emulsion, saline, and no treatment. An increase in arterial blood pressure underlay the recovery in both lipid emulsion-treated groups. Heart rates remained depressed in all four groups throughout the observation period. Model predictions mirrored the experimental recovery, and the model that combined volume, sequestration, and inotropy predicted in vivo results most accurately.

CONCLUSION

Intravenous lipid emulsion accelerates cardiovascular recovery from bupivacaine toxicity in a dose-dependent manner, which is driven by a cardiotonic response that complements the previously reported sequestration effect.

Lipid emulsions enhance the norepinephrine-mediated reversal of local anesthetic-induced vasodilation at toxic doses

PURPOSE

Intravenous lipid emulsions have been used to treat the systemic toxicity of local anesthetics. The goal of this in vitro study was to examine the effects of lipid emulsions on the norepinephrine-mediated reversal of vasodilation induced by high doses of levobupivacaine, ropivacaine, and mepivacaine in isolated endothelium-denuded rat aorta, and to determine whether such effects are associated with the lipid solubility of local anesthetics.

MATERIALS AND METHODS

The effects of lipid emulsions (0.30, 0.49, 1.40, and 2.61%) on norepinephrine concentration-responses in high-dose local anesthetic (6×10(-4) M levobupivacaine, 2×10(-3) M ropivacaine, and 7×10(-3) M mepivacaine)-induced vasodilation of isolated aorta precontracted with 60 mM KCl were assessed. The effects of lipid emulsions on local anesthetic- and diltiazem-induced vasodilation in isolated aorta precontracted with phenylephrine were also assessed.

RESULTS

Lipid emulsions (0.30%) enhanced norepinephrine-induced contraction in levobupivacaine-induced vasodilation, whereas 1.40 and 2.61% lipid emulsions enhanced norepinephrine-induced contraction in both ropivacaine- and mepivacaine-induced vasodilation, respectively. Lipid emulsions (0.20, 0.49 and 1.40%) inhibited vasodilation induced by levobupivacaine and ropivacaine, whereas 1.40 and 2.61% lipid emulsions slightly attenuated mepivacaine (3×10(-3) M)-induced vasodilation. In addition, lipid emulsions attenuated diltiazem-induced vasodilation. Lipid emulsions enhanced norepinephrine-induced contraction in endothelium-denuded aorta without pretreatment with local anesthetics.

CONCLUSION

Taken together, these results suggest that lipid emulsions enhance the norepinephrine-mediated reversal of local anesthetic-induced vasodilation at toxic anesthetic doses and inhibit local anesthetic-induced vasodilation in a manner correlated with the lipid solubility of a particular local anesthetic.