Robert D. Vincent

Nulliparous active labor, epidural analgesia, and cesarean delivery for dystocia.

OBJECTIVE Our purpose was to examine the effect of epidural analgesia on dystocia-related cesarean delivery in actively laboring nulliparous women. STUDY DESIGN Active labor was confirmed in nulliparous women by uterine contractions, cervical dilatation of 4 cm, effacement of 80%, and fetopelvic engagement. Patients were randomized to one of two groups: epidural analgesia or narcotics. A strict protocol for labor management was in place. Patients recorded the level of pain at randomization and at hourly intervals on a visual analog scale. Elective outlet operative vaginal delivery was permitted. RESULTS One hundred women were randomized. No difference in the rate of cesarean delivery for dystocia was noted between the groups (epidural 8%, narcotic 6%; p = 0.71). No significant differences were noted in the lengths of the first (p = 0.54) or second (p = 0.55) stages of labor or in any other time variable. Women with epidural analgesia underwent operative vaginal delivery more frequently (p = 0.004). Pain scores were equivalent at randomization, but large differences existed at each hour thereafter. The number of patients randomized did not achieve prestudy estimates. A planned interim analysis of the results demonstrated that we were unlikely to find a statistically significant difference in cesarean delivery rates in a trial of reasonable duration. CONCLUSIONS With strict criteria for the diagnosis of labor and with use of a rigid protocol for labor management, there was no increase in dystocia-related cesarean delivery with epidural analgesia.

An Evaluation of the Effect of Anesthetic Technique on Reproductive Success After Laparoscopic Pronuclear Stage Transfer - Propofol Nitrous-Oxide Versus Isoflurane Nitrous-Oxide

Background Laparoscopic pronuclear stage transfer (PROST) is the preferred method of embryo transfer after in vitro fertilization in many infertility programs. There are scant data to recommend the use or avoidance of any particular anesthetic agent for use in women undergoing this procedure. The authors hypothesized that propofol would be an ideal anesthetic for laparoscopic PROST because of its characteristic favorable recovery profile that includes minimal sedation and a low incidence of postoperative nausea and vomiting. The purpose of the study was to compare propofol and isoflurane with respect to postanesthetic recovery and pregnancy outcomes after laparoscopic PROST. Methods One hundred twelve women scheduled for laparoscopic PROST were randomized to receive either propofol/nitrous oxide or isoflurane/nitrous oxide for maintenance of anesthesia. Results Visual analog scale scores for sedation were lower in the propofol group than in the isoflurane group at all measurements between 30 min and 3 h after surgery. More women experienced emesis and were given an antiemetic during recovery in the isoflurane group than in the propofol group. However, the percentage of pregnancies with evidence of fetal cardiac activity was 54% in the isoflurane group compared with only 30% in the propofol group (P = 0.023). Also, the ongoing pregnancy rate was greater in the isoflurane group than in the propofol group (54% vs. 29%, P = 0.014). Conclusions Propofol/nitrous oxide anesthesia was associated with lower clinical and ongoing pregnancy rates compared with isoflurane/nitrous oxide anesthesia.

Magnesium sulfate decreases maternal blood pressure but not uterine blood flow during epidural anesthesia in gravid ewes.

The purpose of this study was to determine whether administration of magnesium sulfate decreased maternal blood pressure during epidural anesthesia in gravid ewes. Twenty-two experiments were performed in 11 chronically instrumented animals between 0.8 and 0.9 of timed gestation. The experimental sequence included: 1) T = 0: magnesium sulfate 4 g intravenously over 5 min followed by an infusion of magnesium sulfate at 4 g/h, or normal saline iv followed by an infusion of normal saline alone; 2) T = 135 min: 500 ml normal saline intravenously over 12 min; and 3) T = 150 min: epidural administration of 2% lidocaine. The initial bolus of magnesium sulfate slightly decreased maternal mean arterial pressure (MAP) but increased uterine artery blood flow (UBF). The increase in UBF was accompanied by an increase in fetal PaO2 at 145 min in the magnesium sulfate group but not in the control group. At 165 min (i.e., 15 min after the epidural injection of lidocaine), epidural lidocaine resulted in a median sensory level of T-10 in the magnesium sulfate group and T-11 in the control group. During epidural anesthesia, maternal MAP was lower (P = 0.001) in the magnesium sulfate group than in the control group. At 165 min, maternal MAP was 18 +/- 3% below baseline (P = 0.0001) in the magnesium sulfate group but did not differ significantly from baseline in the control group. Maternal cardiac output and UBF did not differ from baseline after epidural injection of lidocaine in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Prophylactic Angiotensin II infusion during spinal anesthesia for elective cesarean delivery

Background Angiotensin II may prove useful in treating regional anesthesia‐induced hypotension in obstetric patients, because it causes less uterine vasoconstriction than do other vasoconstrictor drugs (such as phenylephrine). This study compared (1) maternal blood pressure and heart rate and (2) fetal status at delivery in parturients given either prophylactic angiotensin II or ephedrine infusion during spinal anesthesia for elective cesarean delivery. Methods Fifty‐four women were randomized to receive either angiotensin II or ephedrine infusion intravenously during spinal anesthesia for elective cesarean section delivery. Simultaneous with subarachnoid injection, infusion of angiotensin II (2.5 [micro sign]g/ml) or ephedrine (5 mg/ml) was initiated at 10 ng [middle dot] kg‐1 [middle dot] min‐1 and 50 [micro sign]g [middle dot] kg‐1 [middle dot] min‐1, respectively. The rate of each infusion was adjusted to maintain maternal systolic blood pressure at 90–100% of baseline. Results Cumulative vasopressor doses (mean +/‐ SD) through 10, 20, and 30 min were 150 +/‐ 100, 310 +/‐ 180, and 500 +/‐ 320 ng/kg in the angiotensin group and 480 +/‐ 210, 660 +/‐ 390, and 790 +/‐ 640 [micro sign]g/kg in the ephedrine group. Maternal heart rate was significantly higher (P < 0.001) during vasopressor infusion in the ephedrine group than in the angiotensin group. Umbilical arterial and venous blood pH and base excess were all significantly higher (P < 0.05) in the angiotensin group than in the ephedrine group. Conclusions Angiotensin II infusion maintained maternal systolic blood pressure during spinal anesthesia without increasing maternal heart rate or causing fetal acidosis.

The EXIT procedure facilitates delivery of an infant with a pretracheal teratoma.

THE ex utero intrapartum technique (EXIT) procedure allows for the continuance of fetoplacental circulation during cesarean section. Initially, only the infants head and shoulders (but not the placenta) are delivered, thus maintaining uteroplacental blood flow. After the infants airway is secured, the umbilical cord is clamped and delivery of the infant is completed. It has proven useful in cases of anticipated difficult airway instrumentation of the neonate (e.g., large fetal neck masses causing airway obstruction). The authors report a case of an antenatally diagnosed, large pretracheal teratoma, wherein the EXIT procedure was used to secure the infants airway during cesarean section performed during general anesthesia.

Ephedrine remains the vasopressor of choice for treatment of hypotension during ritodrine infusion and epidural anesthesia.

Background:Historically, ephedrine has been the vasopressor of choice for treatment of most cases of hypotension in obstetric patients. However, the choice of vasopressor in the parturient receiving a β-adrenergic agent for tocolysis has not been evaluated extensively. The current study evaluated whether ephedrine or phenylephrine better restores uterine blood flow and fetal oxygenation during ritodrine infusion and epidural anesthesia-induced hypotension in gravid ewes. Methods:Fourteen chronically instrumented gravid ewes between 0.8 and 0.9 timed gestational age were used. On separate days, each animal underwent the experimental protocol with one of three agents: ephedrine, phenylephrine, and normal saline-control. The experimental protocol was as follows: (1) at time zero, intravenous infusion of ritodrine was begun; (2) at 120 min, 2% lidocaine was given epidurally to achieve a sensory level of at least T6; and (3) at 135 min, an intravenous bolus of either ephedrine, phenylephrine, or normal saline-control was given, followed by a continuous intravenous infusion of the same agent for 30 min. In the ephedrine and phenylephrine experiments, the rate of infusion was adjusted to maintain maternal mean arterial pressure close to baseline. Results:Ritodrine infusion alone significantly increased maternal heart rate and cardiac output in all three groups. Epidural anesthesia during ritodrine infusion significantly decreased maternal mean arterial pressure, heart rate, cardiac output, uterine blood flow, and fetal arterial oxygen tension for each of the three groups. Both ephedrine and phenylephrine restored maternal mean arterial pressure to baseline, as designed. Ephedrine significantly increased uterine blood flow and fetal arterial oxygen tension when compared with normal saline-control, but phenylephrine did not. Phenylephrine significantly increased uterine vascular resistance when compared with normal saline-control, but ephedrine did not. Conclusions:Although ephedrine and phenylephrine provided similar restoration of maternal mean arterial pressure, ephedrine was superior to phenylephrine in restoring uterine blood flow during ritodrine infusion and epidural anesthesia-induced hypotension in gravid ewes. Also, ephedrine, but not phenylephrine, significantly improved fetal oxygenation, when compared to normal saline-control.

The use of propofol, nitrous oxide, or isoflurane does not affect the reproductive success rate following gamete intrafallopian transfer (GIFT) - A multicenter pilot trial/survey

BACKGROUND Whether anesthetic agents administered during gamete intrafallopian transfer (GIFT) affect reproductive outcome is controversial. This multicenter pilot trial and survey had two purposes: to evaluate the effect of propofol, nitrous oxide, midazolam, and isoflurane on pregnancy outcome after GIFT, and to determine if a larger prospective, randomized study is warranted. METHODS A written invitation was mailed to all 50 fertility programs in the United States that are members of the Society for Assisted Reproductive Technology and perform more than 30 GIFT procedures per year. They were invited to contribute information from the medical records of women who underwent GIFT during the calendar years 1993 and 1994. They were asked to document whether propofol, nitrous oxide, midazolam, a potent inhaled anesthetic agent was used during the GIFT procedure; if the woman became pregnant; and if she delivered at least one live neonate. RESULTS Seven medical centers participated and contributed data from 455 women. The clinical pregnancy rate (number of pregnancies/total number of GIFT procedures) and the delivery rate (number of women who delivered at least one live baby/total number of GIFT procedures) were 35% and 32%, respectively. A statistically significant difference could not be found in the clinical pregnancy or delivery rates between those women who received propofol, nitrous oxide, midazolam, or isoflurane during GIFT and those who did not. CONCLUSIONS No agent-related differences in pregnancy rates were found when propofol, nitrous oxide, isoflurane, or midazolam was used as part of the anesthetic technique for GIFT. Therefore, a more extensive prospective trial does not appear to be warranted.

Which Vasopressor Should Be Used To Treat Hypotension during Magnesium Sulfate Infusion and Epidural Anesthesia

Ephedrine restores and/or protects uterine blood flow and fetal well-being in laboratory animals. In contrast, alpha 1-adrenergic agonists worsen uterine blood flow and fetal condition. We previously demonstrated that magnesium sulfate (MgSO4) attenuates the detrimental effects of phenylephrine on uterine vascular resistance in gravid ewes. Therefore, we performed this study to determine whether ephedrine or phenylephrine better restores and protects uterine blood flow and fetal oxygenation during epidural anesthesia-induced hypotension in hypermagnesemic gravid ewes. Twelve chronically instrumented gravid ewes were each used for three experiments: 1) ephedrine, 2) phenylephrine, and 3) normal saline (NS)-control. For each experiment the protocol was as follows: 1) at time zero, intravenous infusion of MgSO4 was begun; 2) at 150 min a thoracic level of epidural anesthesia was achieved with 2% lidocaine; and 3) at 165 min, an intravenous infusion of ephedrine, phenylephrine, or NS was begun and continued through 195 min. Epidural anesthesia uniformly decreased maternal mean arterial blood pressure (MAP), heart rate, cardiac output, uterine blood flow, and fetal PO2 in each of the three groups. Both ephedrine and phenylephrine restored maternal MAP to baseline, as expected from the experimental design. Ephedrine significantly increased cardiac output and uterine blood flow when compared with NS-control, but phenylephrine did not. Phenylephrine significantly increased uterine vascular resistance when compared with NS-control, but ephedrine did not. As a result, fetal pH and PO2 were significantly greater during ephedrine infusion than during infusion of NS-control. Fetal pH was stable during ephedrine infusion, but it continued to decrease during phenylephrine infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidural anesthesia for postpartum tubal ligation using epidural catheters placed during labor.

STUDY OBJECTIVES To evaluate the success of epidural anesthesia for postpartum tubal ligation using epidural catheters placed during labor and to determine whether patient characteristics, timing of surgery, or technical factors (e.g., length of epidural catheter inserted into the epidural space) influenced the success of subsequent epidural anesthesia. DESIGN Retrospective study. SETTING University hospital labor and delivery suite. PATIENTS 90 consecutive women scheduled for postpartum tubal ligation using epidural catheters placed during labor. INTERVENTIONS Epidural catheters were reinjected with 1.5% to 2% lidocaine with epinephrine 5 micrograms/ml or 2% to 3% 2-chloroprocaine immediately before surgery. MEASUREMENTS AND MAIN RESULTS 74% of the women received satisfactory intraoperative anesthesia using in situ epidural catheters. Reinjecting the catheter within 4 hours of delivery was associated with a greater frequency of successful epidural anesthesia for tubal ligation (95% vs. 67%; p = 0.029). There was no significant difference between the two groups in the length of catheter inserted into the epidural space. CONCLUSIONS Although other factors may influence the timing of postpartum tubal ligation after delivery, the success of epidural anesthesia for tubal ligation using in situ epidural catheters is greater if surgery is performed shortly after delivery.

Does epidural fentanyl decrease the efficacy of epidural morphine after cesarean delivery

Earlier studies have suggested that epidural fentanyl improves intraoperative analgesia during cesarean section, but others have suggested that it worsens postoperative analgesia from epidural morphine. The purpose of this study was to determine whether epidural fentanyl given before epidural morphine improves the quality of intraoperative epidural anesthesia without worsening postoperative analgesia provided by epidural morphine. Sixty patients having epidural anesthesia for cesarean delivery were studied. Epidural anesthesia was established using 2% lidocaine with epinephrine 5 micrograms/mL. After delivery, either fentanyl 100 micrograms/10 mL or normal saline-control 10 mL was injected through the epidural catheter in a randomized, double-blind manner. All patients received 3.5 mg of morphine epidurally after uterine repair. After administration of the epidural study drug, there were no significant differences in the pain responses during surgery between the two groups. Patients in the fentanyl group experienced significantly less nausea and vomiting between delivery and the end of surgery than did patients in the normal saline-control group (P = 0.013). Postoperatively, visual analogue scale scores for pain, pruritus, nausea, and sedation were similar at 1, 2, 4, and 8 h in the two groups. We conclude that fentanyl 100 micrograms administered epidurally during cesarean delivery did not improve intraoperative analgesia, but significantly reduced intraoperative nausea and vomiting without diminishing the efficacy of postoperative analgesia provided by epidural morphine.