The placental transfer and fetal effects of levobupivacaine, racemic bupivacaine, and ropivacaine.
BACKGROUND
The purposes of this study were to assess the effects of levobupivacaine on uterine blood flow and fetal well-being and to compare its placental transfer with that of bupivacaine and ropivacaine.


METHODS
After a control period, pregnant ewes that were fitted with instruments for long-term monitoring were randomized to receive a two-step intravenous infusion of levobupivacaine, bupivacaine, or ropivacaine, in a blinded manner, for 1 h. Maternal and fetal hemodynamics were monitored during the study. Arterial blood samples were drawn at 30 and 60 min of infusion from the mother and fetus to determine the acid-base status (60 min only) and serum drug concentrations. The fetal brain, heart, liver, lungs, adrenal glands, and kidneys were obtained to measure tissue drug levels.


RESULTS
Maternal blood pressure, central venous and intraamniotic pressures, acid-base status and uterine blood flow were unaffected by any drug infusion. In contrast to the other two local anesthetics, the infusion of bupivacaine was associated with a small but significant decrease in the ewe's heart rate. At the end of the study, the heart rate in the bupivacaine-treated animals was significantly less than in the animals treated with the other two drugs. All fetuses were in good condition at the start of study, and none of the local anesthetics affected fetal well-being. No significant differences were found among the three drugs in the maternal serum, fetal serum, fetal tissue concentrations, and tissue:serum concentration ratios.


CONCLUSIONS
Levobupivacaine was similar to bupivacaine and ropivacaine in causing no important hemodynamic changes in the pregnant ewe and fetus. There were no significant differences in the fetal serum and tissue levels of the drugs.
Santos
A C
AC
Department of Anesthesiology, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, New York 10461, USA. Obanesdoc@aol.com
Karpel
B
B
Noble
G
G
D000577:Amides / Q000493:pharmacokinetics* / Q000633:toxicity; D000779:Anesthetics, Local / Q000493:pharmacokinetics* / Q000633:toxicity; D000818:Animals; D002045:Bupivacaine / Q000493:pharmacokinetics* / Q000633:toxicity; D005260:Female; D005333:Fetus / Q000187:drug effects* / Q000378:metabolism; D008431:Maternal-Fetal Exchange; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D012039:Regional Blood Flow / Q000187:drug effects; D000077212:Ropivacaine; D012756:Sheep; D013237:Stereoisomerism; D014599:Uterus / Q000098:blood supply
D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D002045:Bupivacaine