Sanjay Datta

Perioperative Analgesia with Subarachnoid Fentanyl–Bupivacaine for Cesarean Delivery

Addition of fentanyl to bupivacaine administered for spinal anesthesia for cesarean delivery was evaluated in 56 ASA physical status 1 term parturients. Preservative-free saline was added to 0, 2.5, 5, 6.25, 12.5, 25, 37.5, or 50 micrograms fentanyl to make a 1 ml total volume, which was injected intrathecally prior to bupivacaine in a double-blind, randomized fashion. Vital signs, sensory level, motor block, pain score, and side effects were recorded every 2 min for the first 12 min and then at 15, 30, 45, and 60 min and at 30-min intervals until the patient complained of pain. At delivery maternal vein, umbilical artery, and umbilical vein blood gases were obtained. Apgar scores at 1 and 5 min were recorded. Early Neonatal Neurobehavioral Scales (ENNS) were performed on days 1 and 2. Side effects and opioid requirements were recorded for the first 24 h. All of the patients in the control group reported a pain score greater than 0 during surgery and 67% required intraoperative opioids. None of the patients who received greater than or equal to 6.25 micrograms fentanyl required intraoperative opioids. Complete analgesia (time from injection to first report of pain) lasted 33.7 +/- 30.8 min (mean +/- SD) in the control group and increased to 130 +/- 30 min (P less than 0.05) with addition of 6.25 micrograms fentanyl. Duration of effective analgesia (time from injection to first parenteral opioid) was 71.8 +/- 43.2 min in the control group and increased (P less than 0.05) to 192 +/- 74.9 min with addition of 6.25 micrograms fentanyl.(ABSTRACT TRUNCATED AT 250 WORDS)

A Comparison of Intrathecal, Epidural, and Intravenous Sufentanil for Labor Analgesia

A number of recent studies have suggested that the analgesic effects of highly lipid-soluble opioids are similar when these agents are administered either epidurally or intravenously. We sought to test whether the lipid-soluble opioid sufentanil was more effective when administered intrathecally than when administered epidurally or intravenously. Twenty-four women during active labor received sufentanil 10 micrograms either intrathecally (n = 9), epidurally (n = 8), or intravenously (n = 7), using a combined spinal-epidural technique. The sufentanil was administered alone, without concomitant local anesthetics. Analgesia was assessed using the visual analogue score as well as the time elapsed from the administration of study drug to the patients request for additional analgesia via the epidural catheter (bupivacaine 0.25%). The median duration of analgesia (median, interquartile range) was 84 (70-92) min in the intrathecal group, 30 (23-32) min in the epidural group, and 34 (17-30) min in the intravenous group (P < 0.001). The intrathecal group showed rapid and significant decrease in visual analogue scale scores, whereas visual analogue scale scores in the other two groups did not decrease and remained significantly elevated compared to those of the intrathecal group at all observation points. Side effects were limited to pruritus in 3 patients (2 moderate and 1 severe) in the intrathecal group. No patient developed post-dural puncture headache. We conclude that sufentanil 10 micrograms intrathecally provides rapid and effective analgesia of 1-2-h duration during labor. Epidural and intravenous use of this dose of sufentanil did not provide evidence of satisfactory analgesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Association of epidural analgesia with cesarean delivery in nulliparas.

Objective To evaluate whether epidural analgesia during the first stage of labor is associated with an increased risk of cesarean delivery. Methods The association of epidural analgesia and cesarean delivery was examined in a retrospective study of 1733 low-risk, term nulliparas with singleton infants in vertex presentations, in which labor began spontaneously. To evaluate the effect of epidural analgesia on cesarean deliveries, independent of other factors influencing the use of epidural analgesia, we used propensity scores to create five subgroups (quintiles) of women who, based on characteristics discernible at admission, appeared equally likely to receive epidural analgesia. Multivariate logistic regression analysis was used to control for confounding. Results Overall, the cesarean rate among women receiving epidural analgesia was 17% (168 of 991), compared with 4% (30 of 742) among those who did not receive epidural analgesia. An increased cesarean rate among women receiving epidural analgesia was present in all propensity quintiles. In an adjusted logistic regression analysis, women receiving epidural analgesia were 3.7 times more likely to undergo a cesarean (95% confidence interval 2.4, 5.7). The greatest increase in cesarean risk was noted when epidural analgesia was administered earlier in labor, but there was a more than twofold increase regardless of the dilation and station at administration of epidural analgesia. Conclusions Epidural analgesia may increase substantially the risk of cesarean delivery. Although the causal nature of this association remains open to debate, prenatal care providers should routinely discuss the risks and benefits of epidural analgesia with women during their pregnancies so that they can make informed decisions about the use of pain relief during labor.

Spinal anaesthesia for Caesarean section. The influence of hypotension on neonatal outcome.

The effect upon the neonate of a short period of maternal hypotension sustained during the initiation of spinal analgesia for Caesarean section was studied. Babies born to mothers with hypotension were significantly more acidotic than controls although acid‐base levels were still within normal limits. Neuro‐behavioural studies were found to be normal in both groups at 4 and 24 hours. It was concluded that a short period (<2 minutes) of hypotension was not harmful to the neonate.

The addition of bupivacaine to intrathecal sufentanil for labor analgesia

We designed a prospective, randomized, double-blind study to evaluate the efficacy of the combination of intrathecal sufentanil with a low dose of local anesthetic in an attempt to prolong analgesia in labor. Fifty-two patients received one of the following intrathecal study solutions: 2.5 mg of bupivacaine; 10 micro gram of sufentanil; or 2.5 mg of bupivacaine plus 10 micro gram of sufentanil. The mean duration of analgesia (min +/- SD) was significantly different among all three groups: 70 +/- 34 min for bupivacaine, 114 +/- 26 min for sufentanil, and 148 +/- 27 min for bupivacaine-sufentanil (P < 0.001). Visual analog scale (VAS) scores for pain were significantly higher in the bupivacaine group compared to both the sufentanil group and the bupivacaine-sufentanil group (P < 0.02), and were significantly higher in the sufentanil group compared to bupivacaine-sufentanil at 75 min postinjection and beyond (P < 0.02). Hypotension was not observed in the sufentanil group but occurred transiently in the other two groups (P = 0.09). There was no evidence of motor blockade, excessive somnolence, fetal heart rate (FHR) abnormalities, or postdural puncture headache (PDPH) in any of the patients. The addition of 2.5 mg of bupivacaine to 10 micro gram of intrathecal sufentanil significantly prolonged labor analgesia without adverse maternal or fetal effects. (Anesth Analg 1995;81:305-9)

Clinical Effects and Maternal and Fetal Plasma Concentrations of Epidural Ropivacaine Versus Bupivacaine for Cesarean Section

Background Ropivacaine is a new amide local anesthetic structurally similar to bupivacaine and mepivacaine. Previous studies showed that ropivacaine has a similar clinical effect as bupivacaine with regard to sensory anesthesia and slightly less motor blockade than bupivacaine. Ropivacaine appears to be less cardiotoxic and arrhythmogenic than bupivacaine. The clinical and pharmacokinetic effects of 0.5% ropivacaine (5 mg/ml) versus 0.5% bupivacaine (5 mg/ml) when used epidurally for elective cesarean section were investigated. Methods Using a randomized, double-blind study design, 60 ASA physical status 1 or 2 term parturients presenting for elective cesarean section received either 0.5% bupivacaine (150 mg) or 0.5% ropivacaine (150 mg) epidurally in appropriate fractionated doses over a 10-min period. Onset, duration, and regression of sensory and motor blockade were noted until complete resolution was observed. Quality of intraoperative anesthesia and abdominal wall muscle relaxation were noted. Maternal plasma concentrations of local anesthetic were determined before anesthetic administration and 5, 10, 20, 30, and 60 min and 2, 3, 6, 8, 12, and 24 h after drug injection in 20 subjects. Umbilical cord blood was obtained at time of delivery for acid-base values and determination of the free and total plasma concentration of local anesthetic. Neonates also were examined for neurobehavioral assessments by Scanlons and Neurologic and Adaptive Capacity Scores at 2 and 24 h after delivery. Results All patients received satisfactory anesthesia for operation. The onset, duration, and regression of sensory blockade were similar for both groups. Onset of degree 1 and 2 motor blockade was faster, and duration of degree 1 motor block was longer in the group receiving bupivacaine. Hemodynamic sequelae were similar between groups. All neonates had 5-min Apgar scores of 7 or greater and normal acid-base values and neurobehavioral assessments. Pharmacokinetic analysis showed that the Cmax was similar for both drugs (1.3 plus/minus 0.09 for ropivacaine and 1.1 plus/minus 0.09 micro gram/ml for bupivacaine). The T1/2 of the terminal decline in plasma concentration was shorter for ropivacaine versus bupivacaine (5.2 plus/minus 0.60 versus 10.9 plus/minus 1.08 h, respectively; P < 0.01). The free (i.e., unbound) concentrations of ropivacaine were approximately twice those of bupivacaine in both maternal and neonatal blood at the time of delivery. The ratio of umbilical vein to maternal vein concentration of unbound drug was 0.72 for ropivacaine and 0.69 for bupivacaine. Conclusions Ropivacaine, 0.5%, epidurally provided satisfactory and similar sensory anesthesia compared to 0.5% bupivacaine for elective cesarean section. The Cmax was similar for both drugs, although the terminal half-life of ropivacaine was significantly shorter, and the blood concentrations of free ropivacaine were significantly greater than that for bupivacaine. These values were less than concentrations shown to be toxic in animals.

Comparison of bupivacaine- and ropivacaine-induced conduction blockade in the isolated rabbit vagus nerve

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 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.

Anesthesia for the Obstetric Patient with Multiple Sclerosis

Data on all obstetric patients delivering at the Brigham and Womens Hospital during the years 1982 through 1987 were collected. The anesthetic techniques used, the type and amount of anesthetic agents administered, and the postpartum relapse rate of multiple sclerosis patients were compared. Women who received epidural anesthesia for vaginal delivery did not have a significantly higher incidence of relapse than those who received local infiltration. However, all of the women who experienced postpartum relapses had received concentrations of bupivacaine greater than 0.25%. This finding may suggest that a higher concentration of drug over a longer period of time may adversely influence the relapse rate.

Effects of fentanyl and sufentanil on peripheral mammalian nerves.

The effects of fentanyl and sufentanil on peripheral nerves were evaluated in isolated sheathed and desheathed rabbit vagus nerves. The action potential amplitudes of A and C fibers were recorded before and after a 30-min exposure to 50 and 100 μg/ml of fentanyl and sufentanil. A reversible decrease in the action potential amplitude of A fibers in desheathed nerves was observed after exposure to 100 μg/ml of each drug. The action potential amplitude of C fibers was also decreased but not to the same degree as was the A fiber action potential. Pretreatment with naloxone failed to block the reduction in action potential amplitude produced by the two opiates. No evidence of irreversible conduction blockade indicative of local neural toxicity was seen in these studies. The results suggest that high concentrations of fentanyl and sufentanil may exert a weak local anesthetic-type action on peripheral nerves.

Role of needle gauge and tip configuration in the production of lumbar puncture headache

Background and Objectives. Postdural puncture headache (PDPH) is a morbidity that occurs frequently after lumbar puncture. The purpose of this study was to evaluate the role of needle diameter and tip configuration in causing PDPH. The incidence of PDPH was evaluated in parturients because this group of patients is at high risk for developing PDPH and because they often undergo lumbar puncture for spinal anesthesia. Methods. The incidence of PDPH after spinal anesthesia with 26‐ and 27‐gauge Quincke and 25‐gauge Whitacre needles was studied in a series of 4,125 parturients undergoing spinal anesthesia over a 4‐year period. Data were also collected on the incidence of PDPH with 17‐gauge Huber‐tipped Weiss needles in 21,578 parturients receiving lumbar epidural analgesia and/or anesthesia over the same interval. Additionally, the need to treat PDPH with epidural blood patch in all of these patients was studied. Results. The incidence of PDPH was 5.2% with 26‐gauge Quincke needles (1987‐1989), 2.7% with 27‐gauge Quincke needles (1989‐1990), and 1.2% with 25‐gauge Whitacre needles (1990‐1991). During the same periods, the incidence of PDPH with 17‐gauge Weiss needles averaged 1.1%, 1.7% and 1.2%, respectively. As compared with the 26‐gauge Quincke needle, there was a lower incidence of PDPH with the 27‐gauge Quincke (P < .006) and 25‐gauge Whitacre spinal needles (P < .001). The incidence of PDPH with the 25‐gauge Whitacre needle was less than that with the 27‐gauge Quincke needle (P < .05), and it was similar to the overall rate of headache, which occurs occasionally from accidental dural puncture during the performance of lumbar epidural analgesia/anesthesia for labor and cesarean delivery (P = .974). The need for treating PDPH with epidural blood patching was greatest with the 17‐gauge Weiss epidural needle (75.3% of cases), but was similar with the various spinal needles (13‐39%). However, because the Whitacre needle produced the fewest PDPHs, it was associated with the lowest absolute requirement for epidural blood patching. Conclusions. The morbidity associated with lumbar puncture can be decreased by selecting the proper needle gauge and tip configuration. Use of the smallest gauge needle and one that has a noncutting Whitacre tip produces the lowest incidence of PDPH in parturients, a group of patients at increased risk for developing PDPH.