Background: Continuous bilateral thoracic paravertebral blockade has been used for analgesia after cardiac surgery, but its efficacy has never been formally tested.
Method: Fifty adult patients were enrolled in a double-blind, randomised, controlled study of continuous bilateral thoracic paravertebral infusion of 0.5% lidocaine (1 mg.kg-1.hr-1) for analgesia after coronary surgery. Control patients received a subcutaneous infusion of lidocaine at the same rate through catheters inserted at the same locations as the study group. The primary outcome was morphine consumption at 48 hours using patient-controlled analgesia (PCA). Secondary outcomes included pain, respiratory function, nausea and vomiting. Serum lidocaine concentrations were measured on the first two post-operative days.
Results: There was no difference in morphine consumption or in any other outcome measure between the groups. Serum lidocaine concentrations increased during the study, with a maximum of 5.9 mg.l-1. There were no adverse events as a consequence of the study.
Conclusion: Bilateral paravertebral infusion of lidocaine confers no advantage over systemic lidocaine infusion after cardiac surgery.
Clinical trial registration: ISRCTN13424423 ( https://www.isrctn.com ).
Keywords: analgesia; cardiac surgery; concentration; lidocaine; paravertebral.