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Background and Objectives: Recent controversy with the use of intrathecal lidocaine has prompted the search for suitable ambulatory surgery alternatives. The purpose of our study was to evaluate the clinical utility of intrathecal low-dose bupivacaine for outpatient transvaginal oocyte retrieval., Methods: Forty women enrolled and completed our prospective, randomized, double-blinded study of intrathecal hyperbaric bupivacaine 3.75 mg (0.5 mL of 0.75%) with fentanyl 25 microg versus hyperbaric lidocaine 30 mg (2.0 mL of 1.5%) with fentanyl 25 microg. Onset and level of sensory and motor block; time to ambulation, urination, and discharge; and intra- and postoperative complications (hypotension, pruritus, nausea, emesis, postdural puncture headache, post spinal pain syndrome [PSPS]) were recorded. Data were evaluated using analysis of variance, chi-squared, and Mann-Whitney U tests, with P <.05 considered significant., Results: In demographically similar groups, no differences were noted in times to onset and recovery of sensory and motor function, or complications; however, times to voiding and discharge were significantly longer in the bupivacaine group. Four and 2 patients in the bupivacaine and lidocaine groups, respectively, required intravenous analgesic supplementation. One patient in the lidocaine group experienced PSPS., Conclusions: Although prolongation to voiding and discharge was observed, intrathecal hyperbaric bupivacaine 3.75 mg with fentanyl 25 microg is a viable anesthetic for oocyte retrieval.

Unlabelled: Pregnancy-related decreases in protein binding may contribute to altered effects of local anesthetics in the parturient. Previous studies have measured protein binding of bupivacaine in term parturients; the current study defines the ratio of bound-to-free bupivacaine throughout gestation at both therapeutic and toxic systemic concentrations of bupivacaine. Venous samples were obtained from 81 women, including 70 parturients, ranging from 7 to 42 wk of gestation and 11 nonpregnant controls. The percent bound bupivacaine at a fixed concentration was determined for each sample at both therapeutic (1 microg/mL) and toxic (5 microg/mL) concentrations using an ultrafiltration technique. Albumin and alpha-1-glycoprotein levels were also measured. Linear regression analysis showed a significant increase in concentration of free bupivacaine throughout gestation at the 5-microg/mL concentration, corresponding to a decrease demonstrated in both albumin and alpha-1-glycoprotein levels. A similar correlation was not found at the 1-microg/mL concentration. Although the relative magnitude of these changes is small, the relative change in free drug throughout gestation is large. Protein binding is only one of several mechanisms that may influence the susceptibility to local anesthetic toxicity in the parturient; however, its relative importance remains unclear., Implications: When venous samples taken from pregnant women were mixed with 5 microg/ml bupivacaine and analyzed, an increase in the free fraction of drug was seen with increasing gestational age, corresponding to decreases in alpha-1-glycoprotein and albumin.

Background: Bupivacaine exists as a mixture of two enantiomers, levobupivacaine and dexbupivacaine. Data suggest that levobupivacaine has equal local anesthetic potency, with reduced potential for central nervous system and cardiovascular toxicity. The present study compares the efficacy of 0.5% levobupivacaine with 0.5% bupivacaine for epidural anesthesia in parturients undergoing elective cesarean delivery., Methods: Sixty healthy obstetric patients undergoing elective cesarean delivery with epidural anesthesia completed the study. Patients were randomized to receive 30 ml of either 0.5% levobupivacaine or 0.5% bupivacaine in a double-blind fashion. The efficacy endpoint measures included onset, offset, and quality of anesthesia. Neonatal blood gas analyses, Apgar score determinations, and neurobehavioral examinations were performed. Venous samples for pharmacokinetic studies and serial electrocardiograms were obtained in 10 patients in each group., Results: Levels of sensory block, motor block, muscle relaxation, and overall quality of anesthesia did not differ between groups. The frequency of hypotension was 84.4% in the levobupivacaine group and 100% for the bupivacaine group (P < or = 0.053). No significant difference in observed maximum concentration of drug after dosing or area under the plasma drug concentration versus time curve were seen. The maximum concentrations were 1.017 and 1.053 microg/ml, and the areas were 4.082 and 3.765 h(microg/ml) for the levobupivacaine and bupivacaine groups, respectively. Umbilical vein-to-maternal vein ratios were 0.303 for the levobupivacaine group and 0.254 for the bupivacaine group., Conclusions: The use of epidural 0.5% levobupivacaine for cesarean delivery results in equally efficacious anesthesia compared with 0.5% bupivacaine. Pharmacokinetic parameters were similar in the two groups.

Background: Patients having in vitro fertilization (IVF) procedures that use gonadotropin-releasing hormone agonist down-regulation undergo hormonal manipulation of estrogen concentrations to induce oocyte maturation. After achieving minimal estrogen concentrations (baseline), stimulation increases estrogen concentrations to supraphysiologic levels, leading to egg retrieval. The isolated effect of estrogen on protein binding has not previously been reported. This study was conducted to measure the effect of estrogen concentrations on protein binding of two concentrations of bupivacaine, 1 microg/ml and 5 microg/ml, corresponding, respectively, to systemic concentrations expected after administration of epidural anesthesia and associated with bupivacaine toxicity. Serum proteins were measured to address the mechanism., Methods: Twenty-nine healthy women undergoing IVF procedures were enrolled and venous samples were drawn at times of minimal and maximal estrogen concentrations. The percentage of free bupivacaine was determined at fixed concentrations of 1 and 5 microg/ml. Serum albumin and alpha1-acid glycoprotein concentrations were measured at baseline and at retrieval in a group of 24 women., Results: The percentage of free bupivacaine increased between times of minimal and maximal serum estrogen concentrations, corresponding to decreased protein binding. Concentrations of serum albumin and alpha1-acid glycoprotein decreased between baseline and retrieval times., Conclusions: Patients undergoing IVF procedures demonstrate a decrease in protein binding of bupivacaine from baseline concentrations. These changes may be explained by a decrease in albumin and alpha1-acid glycoprotein. During anesthesia for egg retrieval, clinicians should consider the implications of increased free fraction of drug, especially for highly protein-bound agents.

Study Objectives: To provide information on the central hemodynamic effects of intrathecal sufentanil after a standard intravenous preload using thoracic bioimpedance monitoring to obtain noninvasive measurements of cardiac index (CI), stroke index (SI), and systemic vascular resistance (SVR). To compare hemodynamic parameters after intrathecal sufentanil labor analgesia to those after a standard dose of epidural bupivacaine in laboring parturients., Design: Randomized, double-blind study., Setting: Labor and delivery unit in a university hospital., Study Design: 40 ASA status I parturients were randomized into two groups receiving analgesia with combined spinal-epidural technique. Group SUF received 10 micrograms of intrathecal sufentanil followed by 12 ml of saline through an epidural catheter; Group BUP received 2 ml of intrathecal saline followed by 12 ml of 0.25% epidural bupivacaine. Heart rate (HR), blood pressure (BP), and thoracic bioimpedance monitoring were recorded. Pain scores, fetal HR, and side effects were noted., Measurements and Main Results: No significant changes from baseline were seen in CI, SI, or SVR index. Mean arterial pressure was lower in Group BUP at 10 and 20 minutes after induction of analgesia. Mean HR was lower in Group SUF at 20 and 30 minutes after induction. Two patients in Group SUF and four patients in Group BUP experienced hypotension requiring ephedrine. Pain scores were lower in Group SUF at 10 minutes after induction of analgesia; subsequent pain scores and duration of analgesia were similar. Fourteen patients in Group SUF experienced itching., Conclusions: No significant differences in CI, SI, or SVR index were seen after either method of analgesia. A few patients in both groups experienced hypotension requiring treatment with ephedrine. Both techniques of labor analgesia appear to provide effective pain relief but care must be taken with either method to monitor maternal BP.

Labor analgesia using continuous epidural infusions of low-dose bupivacaine and fentanyl may be maintained for many hours. We examined the potential for drug accumulation in both mother and neonate after these long-term infusions. Pregnant women receiving a 10-mL/h continuous infusion of labor analgesia with 0.125% bupivacaine and 2 micrograms/mL of fentanyl were evaluated. Maternal venous and umbilical venous drug concentrations were measured at delivery. Umbilical artery blood gases were obtained. Scanlon neurobehavioral testing was performed on all infants. Length of infusion times varied from 1 to 15 h. Maternal and neonatal drug concentrations remained relatively constant throughout the infusion period. All umbilical blood gas values and neurobehavioral scores were within normal limits. In conclusion, even when maintained for many hours, continuous infusion labor analgesia does not appear to result in significant fetal drug accumulation. No adverse neonatal effects were seen.

The current study was initiated to evaluate the epidural anesthetic properties of 0.5%, 0.75%, and 1.0% ropivacaine, a new local anesthetic agent structurally similar to bupivacaine. Fifteen patients scheduled for lower limb orthopedic surgery were enrolled in the study. As the concentration of ropivacaine increased from 0.5% to 1.0%, the time to onset of sensory anesthesia decreased from 6.4 +/- 1.7 (SD) min to 2.4 +/- 0.6 min and the maximum level of sensory anesthesia increased from T6 to T1. These changes were not statistically significant. Time to regression of anesthesia to T12 increased from 255 +/- 73 min with the 0.5% solution to 356 +/- 75 min with 1.0% ropivacaine (P less than 0.05). The degree of motor blockade using the Bromage scale varied with the concentration. When the 0.5% concentration was used, only one patient (20%) had greater than 1+ motor blockade. However, all of the patients receiving the 0.75% or 1.0% solution had at least 2+ motor blockade. Sensory anesthesia was adequate for surgery in 14 of the 15 patients. The mean peak plasma concentration of ropivacaine (Cmax) increased from 0.65 +/- 0.15 micrograms/mL with the 100-mg dose to 1.30 +/- 0.43 microgram/mL with the 200-mg dose. No adverse effects were noted in any patient in the study. These initial studies in humans suggest that ropivacaine provides satisfactory sensory anesthesia with minimal motor blockade at a concentration of 0.5%. An increase in concentration resulted in a more profound motor blockade. The Cmax of ropivacaine in this study was below levels associated with toxicity in animal studies.

Ropivacaine (LEA-103) is a new amino-amide local anesthetic agent the chemical structure and anesthetic properties of which are similar to bupivacaine. Preliminary studies in animals indicate that the CNS toxicities of ropivacaine and bupivacaine are similar, but that ropivacaine may have less arrhythmogenic effects than bupivacaine. The current study arrhythmogenic effects than bupivacaine. The current study was designed to compare the in vitro potency, onset and recovery from block of ropivacaine and bupivacaine using an isolated rabbit vagus nerve model. The effect of varying concentrations of ropivacaine and bupivacaine on the compound action potential of A and C nerve fibers was assessed to determine whether motor and sensory fibers have different sensitivities to the two agents. The results showed that the depressant effect of bupivacaine was 16% greater than that of ropivacaine on motor fibers, but only 3% greater on sensory fibers. An analysis of variance indicated that this was a statistically significant difference (P = 0.028). Thus, at the concentrations tested, ropivacaine appears to produce relatively less blockade of motor fibers than does bupivacaine but with similar sensory blockade. The onset of this difference became significant as early as five minutes after the drug exposure was begun. No significant differences in recovery times were observed.