Electrophysiologic cardiac effects of the new local anesthetic IQB-9302 and of bupivacaine in the anesthetised dog

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.

The comparative hemodynamic effects of intravenous IQB-9302 and bupivacaine in anesthetized rats

BACKGROUND

The new local anesthetic IQB-9302 is an amide derivative bearing a cyclopropyl group, with remarkable long duration of action and relative low toxicity. In trying to characterize further its safety profile, the current study compared the hemodynamic effects of different concentrations of bupivacaine and IQB-9302 with saline.

METHODS

Two groups of eight anesthetized Sprague-Dawley rats were given 0.1, 0.3, 1, 3, and 10 mg/kg of intravenous (i.v.) IQB-9302 or bupivacaine at 20-min intervals; control animals received saline only. Arterial blood pressure and heart rate were monitored during the following 20 min.

RESULTS

Both bupivacaine and IQB-9302 reduced heart rate: for bupivacaine, -73.8 beats per min (bpm) (SD: 103.8) and -132.5 bpm (SD: 140.7) at 1 and 3 mg/kg, respectively; for IQB-9302, the reduction amounted to -40.8 bpm (SD: 14.2) and -113.5 bpm (SD: 94.2) at 1 and 3 mg/kg, respectively (baseline range, 318.7-438.2 bpm). The two drugs also produced a comparable increase in the mean arterial blood pressure; bupivacaine increased it by 8.7 mmHg (SD: 6.6) and 12.6 mmHg (SD: 15.4) at 1 and 3 mg/kg, respectively, and IQB-9302, 18.7 mmHg (SD: 21.1) and 20.7 mmHg (SD: 20.5) at 1 and 3 mg/kg, respectively (baseline range, 47.4-134.1 mmHg). All rats treated with 10 mg/kg of either drug died after a drop in heart rate and mean arterial blood pressure.

CONCLUSION

IQB-9302 had hemodynamic effects similar to those of bupivacaine in anesthetized rats. The clinical relevance of these effects warrants further investigation.