Low-Dose Enflurane as Adjunct to High-Dose Fentanyl in Patients Undergoing Coronary Artery Surgery

The pharmacokinetics and maternal and neonatal effects of epidural lidocaine were compared in ten preeclamptic and five normotensive women undergoing cesarean section at 36-40 weeks of gestation. Lumbar epidural anesthesia was achieved using 15-20 ml of 2% lidocaine without epinephrine. Serial venous samples for lidocaine levels were drawn from all the mothers during the procedure and up to 6 hr after the initial injection. Umbilical venous and arterial samples were drawn at delivery for measurement of neonatal acid-base status and lidocaine levels. There were no significant differences between normotensive and preeclamptic patients in the total dose of lidocaine, peak maternal plasma concentration, volume of distribution, maternal elimination half-life and umbilical vein/maternal vein ratios. The calculated area under the concentration time curve in pre- eclamptic patients (18.5 ± 4.7 μg•hr•ml-1) was significantly greater than in normotensive mothers (14.1 ± 1.3 μg•hr•ml-1) (P < 0.02). Total maternal body clearance in preeclamptic patients (24.5 ± 7.1 L/hr) was significantly lower than in normotensives (31.1 ± 4.4 L/hr) (P < 0.05). Neonatal outcome as evaluated by Apgar scores, umbilical arterial and venous blood gas tensions, umbilical vein/maternal vein ratios, and early neonatal neurobehavior scores at 4 hr and 24 hr after birth were similar in the two groups. The results indicate that the total maternal body clearance of lidocaine is prolonged in preeclampsia, and repeated administration of lidocaine can result in higher blood levels than in normotensive parturients.