Bupivacaine-induced QRS prolongation is enhanced by lidocaine and by phenytoin in rabbit hearts

Dexmedetomidine enhances tolerance to bupivacaine cardiotoxicity in the isolated rat hearts: alpha 2 adrenoceptors were not involved

Background

Dexmedetomidine was proved to mitigate bupivacaine-induced cardiotoxicity but mechanism of this ability is still unclear. This study was designed to investigate the direct effects of dexmedetomidine on cardiotoxicity induced by bupivacaine on Langendorff rat heart preparation and the role of alpha 2 adrenoceptors in this process was explored.

Methods

Hearts of rat were isolated, mounted on a Langendorff system. Five experimental groups were assessed after 10 min Krebs-Henseleit buffer (KHB) infusions as follow: (1) Group Con, only KHB was perfused; (2) Group Dex, KHB was perfused for 5 min, then dexmedetomidine (10 nmol/L) was added; (3) Group Bupi, KHB was perfused for 25 min, then bupivacaine (50 μmol/L) was added; (4) Group Bupi + Dex, KHB was perfused for 5 min, then the dexmedetomidine (10 nmol/L) was added for 20 min, at last a mixture of KHB + dexmedetomidine + bupivacaine were perfused; (5) Group Bupi + Dex + Yoh, a combination of KHB + yohimbine (alpha 2 adrenoceptor antagonists, 1 μmol/L) was perfusion for 5 min, then dexmedetomidine (10 nmol/L) was added for 20 min, at last a mixture of KHB + yohimbine + dexmedetomidine + bupivacaine was perfused. The experimental perfusion was maintained for 35 min in group Con and group Dex, and the experimental perfusion was sustained until asystole in the other three groups.

Results

Compared with group Bupi, dexmedetomidine significantly increased the time to first arrhythmia (P <  0.001) and time to asystole (P <  0.001) in group Bupi + Dex. In addition, dexmedetomidine also significantly increased the time to 25, 50 and 75% reductions in heart rate (P <  0.001) and the time to 25, 50 and 75% reductions in rate-pressure product (P <  0.001) in group Bupi + Dex. Dexmedetomidine increased the cardiac tissue bupivacaine content when asystole (Bupi + Dex vs. Bupi, 58.5 ± 6.3 vs. 46.8 ± 5.6 nmol/g, P = 0.003). The benefit of dexmedetomidine on bupivacaine-induced cardiotoxicity were not eliminated by yohimbine.

Conclusions

Dexmedetomidine could delay the occurrence of bupivacaine-induced arrhythmia and asystole in the isolated rat hearts, but the alpha 2 adrenoceptors were not involved in this process.

The Effects of Lidocaine with Epinephrine on Bupivacaine-Induced Cardiotoxicity

Objective

Bupivacaine, a local anaesthetic substance, is used as a regional-anaesthesia agent. Lidocaine, a sodium channel blocker, is used in combination with epinephrine for regional anaesthesia. We aimed to evaluate the effects of lidocaine with epinephrine (LE) at different doses on bupivacaine-induced cardiotoxicity in rats.

Methods

In our study, 24 Wistar albino rats were divided into four groups: I) Control; II) LE, 1 mg kg^-1; III) LE, 3 mg kg^-1 and IV) LE, 6 mg kg^-1. Intravenous bupivacaine was administered at a dose of 3 mg kg^-1 min^-1 to the anaesthetized rats in all groups until cardiac asystole was achieved. LE was administered at the doses of 1, 3 and 6 mg kg^-1 min^-1 using infusion, simultaneously with bupivacaine. The asystole time and 75% decrement time in mean arterial blood pressure (MABP) were determined. P-Q, Q-T and QRS intervals were measured using electrocardiography (ECG) recordings.

Results

LE significantly increased the asystole time and 75% decrement time in MABP at the doses of 3 and 6 mg kg^-1 compared to the control group (p<0.05) and significantly increased these values at the dose of 1 mg kg^-1 compared to the control and other treatment groups (p<0.05). LE abolished the prolongation of P-Q, Q-T and QRS intervals in ECG recordings at the dose of 1 mg kg^-1 (p<0.05).

Conclusion

These results reveal that LE has a protective effect against bupivacaine cardiotoxicity. In clinical application, the simultaneous application of LE and bupivacaine may reduce the risk of cardiotoxicity due to bupivacaine.

Pharmacokinetic Compatibility Study of Lidocaine with EXPAREL in Yucatan Miniature Pigs

We explored the potential for EXPAREL to interact with lidocaine. Sixty (60) male Yucatan Swine were randomized into 20 groups (N = 3/group). EXPAREL (2 or 4 mg/kg) and/or lidocaine HCl solution 1% or 2% (with epinephrine 1 : 200,000) were injected subcutaneously along a 5 cm virtual incision line. The effects on the pharmacokinetics of bupivacaine and lidocaine were examined when 5, 10, 20, and 40 minutes had passed between administration of lidocaine and EXPAREL. Systemic exposure to lidocaine was increased (AUC_0−24 hr by 48%; C_max by 1,640%) when lidocaine (4 mg/kg) was followed 5 minutes later by EXPAREL (4 mg/kg) compared to lidocaine administered alone. Plasma bupivacaine was increased (AUC_0−24 hr by 50–95%; C_max by 67–1,000%) when lidocaine (4 mg/kg) was followed 5 or 10 minutes later by EXPAREL (4 mg/kg) compared to EXPAREL alone. While EXPAREL should not be admixed with lidocaine, this study shows that local administration of EXPAREL after at least 20 minutes following local administration of lidocaine did not increase the release of either drug.

Hemodynamic Effects of Interpleural Lidocaine and Bupivacaine Combination in Anesthetized Dogs with and Without an Open Pericardium

OBJECTIVE

To identify dysrhythmias and hemodynamic changes after lidocaine and bupivacaine infusion into the interpleural space with an open pericardium.

STUDY DESIGN

Experimental study.

ANIMALS

Six adult dogs.

METHODS

Systemic arterial pressure and electrocardiogram were recorded. A 7.5 Fr Swan-Ganz catheter was advanced to the level of the main pulmonary artery to record pulmonary arterial pressure. Cardiac output was measured by a thermodilution technique. A pericardial window (PW) was performed in 3 dogs using thoracoscopy. Hemodynamic variables were recorded before and 15 minutes after injection of lidocaine (1.5 mg/kg) and bupivacaine (1.5 mg/kg) into the pleural space in the control group and in the pericardial space for the PW group. A randomized-block ANOVA for repeated measures was used to evaluate the effect of local anesthetic administration on hemodynamic and electrophysiologic variables in dogs with a pericardectomy.

RESULTS

Each dog maintained sinus rhythm. Infusion of local anesthetic induced a significant increase in right ventricular diastolic pressure (P = .002) and a significant decrease in stroke volume (P = .047) in both groups; however, the effects were not significantly different between groups.

CONCLUSIONS

Infusion of lidocaine and bupivacaine, either intrapleural or in the pericardial space, had a mild detrimental effect on cardiac output.

CLINICAL RELEVANCE

Intrapleural administration of lidocaine and bupivacaine at a therapeutic dose can be used safely in healthy dogs with a pericardectomy.