title: [Comparison of the hemodynamic effects in acute intoxication with racemic bupivacaine and with 50% enantiomeric excess mixture (S75-R25): an experimental study in dogs.].
abstract: OBJECTIVE
  Racemic bupivacaine has been widely used in locoregional anesthesia due to the quality and duration of its anesthetic action. However, its cardiovascular toxicity has worried anesthesiologists for a long time, and new options have been sought. One of them is the use of its levorotatory isomer that, due to a lesser affinity for the sodium channel receptors in the cardiac cell, would be less toxic. The presentation containing 75% of the levorotatory isomer and 25% of the dextrorotatory isomer, named 50% enantiomeric excess mixture (S75-R25), is available in our country. The objective of this study was to compare the hemodynamic effects of the acute intoxication with racemic bupivacaine and with the S75-R25 mixture in animals.
  
  
  METHODS
  Forty-four dogs were anesthetized with pentobarbital, intubated and placed on mechanical ventilation. Hemodynamic monitorization was accomplished with a Swan-Ganz catheter and intra-arterial blood pressure measurements. After a period of rest, they were randomly and blindly divided in two groups, according to the intoxication with either agent at a dose of 5 mg.Kg-1. Hemodynamic data were collected during 30 minutes and analyzed statically to allow for the comparison of both agents.
  
  
  RESULTS
  The mixture S75-R25 had more hemodynamic repercussions causing, especially, a significant reduction of the mean arterial pressure, cardiac index, and the left ventricle work index.
  
  
  CONCLUSIONS
  These results contradict those found in human beings regarding the pure levorotatory isomer, but confirm recent animal studies. One must be very careful when extrapolating animal data to human beings. Further studies involving larger samples and more homogeneous groups are necessary.
authors.affiliation: Departamento de Anestesiologia, FCM, UNICAMP.
authors.forename: Artur
authors.initials: A
authors.lastname: Udelsmann
authors.forename: Derli Conceição
authors.initials: DC
authors.lastname: Munhoz
authors.forename: William Adalberto
authors.initials: WA
authors.lastname: Silva
authors.forename: Ana Cristina de
authors.initials: AC
authors.lastname: Moraes
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Marcondes