The comparative electrophysiologic and hemodynamic effects of a large dose of ropivacaine and bupivacaine in anesthetized and ventilated piglets.
Ropivacaine is less potent and less toxic than bupivacaine. We administered these two local anesthetics in a cardiac electrophysiologic model of sodium thiopental-anesthetized and ventilated piglets. After assessing the stability of the model, bupivacaine (4 mg/kg) and ropivacaine (6 mg/kg) were given IV in two groups (n = 7) of piglets. No alteration in biological variables was reported throughout the study. Bupivacaine and ropivacaine similarly decreased mean aortic pressure from 99 +/- 22 to 49 +/- 31 mm Hg and from 87 +/- 17 to 58 +/- 28 mm Hg, respectively, and decreased the peak of the first derivative of left ventricular pressure from 1979 +/- 95 to 689 +/- 482 mm Hg/s and from 1963 +/- 92 to 744 +/- 403 mm Hg/s, respectively. Left ventricular end-diastolic pressure was similarly increased from 6 +/- 5 to 9 +/- 5 mm Hg and from 6 +/- 4 to 12 +/- 4 mm Hg, respectively. Bupivacaine and ropivacaine similarly lengthened the cardiac cycle length (R-R; from 479 +/- 139 to 706 +/- 228 ms and from 451 +/- 87 to 666 +/- 194 ms, respectively), atria His (from 71 +/- 15 to 113 +/- 53 ms and from 64 +/- 6 to 86 +/- 10 ms, respectively), and QTc (QTc = QT x R-R(-0.5), Bazett formula; from 380 +/- 71 to 502 +/- 86 ms and from 361 +/- 33 to 440 +/- 56 ms, respectively) intervals. Bupivacaine altered to a greater extent the PQ (the onset of the P wave to the Q wave of the QRS complex) (from 97 +/- 20 to 211 +/- 60 ms versus from 91 +/- 8 to 145 +/- 38 ms, P < 0.05), QRS (from 58 +/- 3 to 149 +/- 34 ms versus from 60 +/- 5 to 101 +/- 17 ms, P < 0.05), and His ventricle interval (from 25 +/- 4 to 105 +/- 30 ms vs from 25 +/- 4 to 60 +/- 30 ms, P < 0.05) than ropivacaine. A 6 mg/kg ropivacaine dose induced similar hemodynamic alterations as 4 mg/kg bupivacaine. However, bupivacaine altered the variables of ventricular conduction (QRS and His ventricle) to a greater extent.


CONCLUSIONS
A 6 mg/kg ropivacaine dose induced similar hemodynamic alterations as 4 mg/kg bupivacaine. However, bupivacaine altered the variables of ventricular conduction (QRS and His ventricle) to a greater extent.
Lefrant
J Y
JY
Department of Anesthesiology, University-Hospital of Nîmes, France.
de La Coussaye
J E
JE
Ripart
J
J
Muller
L
L
Lalourcey
L
L
Peray
P A
PA
Mazoit
X
X
Sassine
A
A
Eledjam
J J
JJ
D000577:Amides / Q000008:administration & dosage* / Q000633:toxicity; D000758:Anesthesia; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000633:toxicity; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage* / Q000633:toxicity; D004562:Electrocardiography / Q000187:drug effects*; D006321:Heart / Q000187:drug effects; D006329:Heart Conduction System / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007275:Injections, Intravenous; D009200:Myocardial Contraction / Q000187:drug effects; D012121:Respiration, Artificial; D000077212:Ropivacaine; D013552:Swine; D017725:Ventricular Pressure / Q000187:drug effects
D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D002045:Bupivacaine