Holly A. Muir

A Multicenter Randomized Controlled Trial Comparing Patient-Controlled Epidural with Intravenous Analgesia for Pain Relief in Labor

In this multicenter, randomized, controlled trial, we sought to determine whether patient-controlled epidural analgesia (PCEA) for labor affected the incidence of cesarean delivery when compared with patient-controlled IV opioid analgesia (PCIA). Healthy, term nulliparous patients in 4 Canadian institutions were randomly assigned to receive PCIA with fentanyl (n = 118) or PCEA with 0.08% bupivacaine and fentanyl 1.6 &mgr;g/mL (n = 124). There was no difference in the incidence of cesarean delivery—10.2% (12 of 118) versus 9.7% (12 of 124)—or instrumental vaginal delivery—21.2% (25 of 118) versus 29% (36 of 124)—between groups. The duration of the second stage of labor was increased in the PCEA group by a median of 23 min (P = 0.02). Fifty-one patients (43%) in the PCIA group received epidural analgesia: 39 (33%) because of inadequate pain relief and 12 (10%) to facilitate operative delivery. Patients in the PCIA group required more antiemetic therapy (17% versus 6.4%; P = 0.01) and had more sedation (39% versus 5%; P < 0.001). Maternal mean pain and satisfaction with analgesia scores were better in the PCEA group (P < 0.001 and P = 0.02, respectively). More neonates in the PCIA group required active resuscitation (52% versus 31%; P = 0.001) and naloxone (17% versus 3%; P < 0.001). These observations support the hypothesis that PCEA does not result in an increased incidence of obstetrical intervention compared with PCIA. PCEA provides superior analgesia and less maternal and neonatal sedation compared with PCIA.

Single-Dose, Sustained-Release Epidural Morphine in the Management of Postoperative Pain After Elective Cesarean Delivery: Results of a Multicenter Randomized Controlled Study

In this multicenter, randomized, controlled study, we compared the analgesic efficacy and safety profile of a new single-dose extended-release epidural morphine (EREM) formulation (DepoDur™) with that of epidural morphine sulfate for the management of postoperative pain for up to 48 h after elective cesarean delivery. ASA physical status I or II parturients (n = 75) were anesthetized with a combined spinal/epidural technique. Parturients received intrathecal bupivacaine 12–15 mg and fentanyl 10 &mgr;g for spinal anesthesia and a single epidural injection of either 5 mg of standard (conventional preservative-free) morphine or 5, 10, or 15 mg of extended-release morphine after cord clamping for postoperative pain control. Single-dose EREM 10 and 15 mg groups significantly decreased total supplemental opioid medication use and improved functional ability scores for 48 h after surgery compared with those receiving 5 mg of standard morphine. Visual analog scale pain scores at rest and with activity at 24 to 48 h after dosing were significantly better in the 10- and 15-mg single-dose EREM groups versus the standard morphine group. There were no significant differences between the two 5 mg (single-dose EREM and standard morphine) groups. Single-dose EREM was well tolerated, and most adverse events were mild to moderate in severity. Single-dose EREM is a potentially beneficial epidural analgesic for the management of post-cesarean delivery pain and has particular advantages over standard morphine for the period from 24 to 48 h after surgery.

A double-blind, placebo-controlled trial of four fixed rate infusion regimens of phenylephrine for hemodynamic support during spinal anesthesia for cesarean delivery.

BACKGROUND: The administration of prophylactic phenylephrine infusions in combination with fluid cohydration significantly reduces the incidence of hypotension in women having cesarean delivery under spinal anesthesia. The ideal dosing regimen for this purpose is not known. In this study, we investigated the dose of phenylephrine that, when administered as a prophylactic fixed rate infusion, is associated with the least interventions needed to maintain maternal systolic blood pressure (SBP) within 20% of baseline. METHODS: Women undergoing elective cesarean delivery were randomly allocated to receive placebo or prophylactic phenylephrine infusion at 25, 50, 75, or 100 &mgr;g/min immediately after spinal anesthesia in combination with a 2-L fluid coload. Maternal SBP was maintained within the target range using a predetermined algorithm. The number of physician interventions, hemodynamic performance, intraoperative nausea and vomiting, and umbilical cord blood gases were compared among the groups. RESULTS: One hundred one patients were included in the analysis. There were no differences between the placebo and phenylephrine groups in the number of interventions needed to maintain maternal SBP within the target range. Doses of phenylephrine of 25 and 50 &mgr;g/min were associated with significantly fewer interventions when compared with 100 &mgr;g/min (P = 0.004 vs 50 &mgr;g/min, P = 0.02 vs 25 &mgr;g/min). Predelivery hypotension was more frequent in the control group compared with all phenylephrine groups. Phenylephrine 75 and 100 &mgr;g/min groups were associated with a significantly higher incidence of predelivery hypertension compared with control (P < 0.001 vs 75 &mgr;g/min and 100 &mgr;g/min). There was a trend toward an increase in median magnitude of deviations of SBP above or below baseline (P = 0.006), and the bias of SBP to be above baseline (P < 0.001) with increasing rates of phenylephrine infusion. There were no differences in the incidence and severity of intraoperative nausea and vomiting and umbilical cord blood gases among the groups. CONCLUSIONS: The use of prophylactic fixed rate phenylephrine infusions did not significantly reduce the number of physician interventions needed to maintain maternal predelivery SBP within 20% of baseline compared with placebo. However, prophylactic phenylephrine infusions reduced the incidence and severity of maternal predelivery hypotension. Phenylephrine 25 and 50 &mgr;g/min administered as a prophylactic fixed rate infusion provided greater maternal hemodynamic stability than phenylephrine 75 and 100 &mgr;g/min. Prophylactic fixed rate infusions may have limited application in clinical practice, and future studies assessing the accuracy of hemodynamic control with variable rate phenylephrine infusions are needed.

Continuous epidural ropivacaine 0.2% for analgesia after lower abdominal surgery

The purpose of this study was to determine whether a lumbar epidural infusion of ropivacaine 0.2% would provide effective analgesia with an acceptably low incidence of motor blockade and side effects after lower abdominal surgery. After combined general and epidural anesthesia and surgery, 125 patients were randomly assigned to receive either saline or ropivacaine 0.2% at a rate of 6, 8, 10, 12, or 14 mL/h (Groups R6, R8, R10, R12, and R14, respectively) for 21 h. Supplemental analgesia, if required, was provided with intravenous patient-controlled analgesia with morphine. Data were collected at 4, 8, and 21 h, and included morphine consumption, pain scores at rest and with coughing, motor and sensory block, and adverse events. Cumulative morphine consumption was less in Groups R10, R12, and R14 compared with the saline group. At 4 h analgesia was better among patients receiving ropivacaine, but at 21 h pain scores were identical. Sensory blockade at 8 and 21 h was greater in the ropivacaine groups compared with the saline group. Approximately 30% of R8, R10, and R12 patients, and 63% of R14 patients had demonstrable motor block of the lower limbs at 21 hours. We conclude that lumbar epidural ropivacaine 0.2% reduces parenteral morphine requirements but has little effect on pain scores and may be associated with motor blockade. (Anesth Analg 1997;84:784-90)

A Multicenter, Randomized, Controlled Trial Comparing Bupivacaine with Ropivacaine for Labor Analgesia

Background A meta-analysis of studies comparing high doses of bupivacaine with ropivacaine for labor pain found a higher incidence of forceps deliveries, motor block, and poorer neonatal outcome with bupivacaine. The purpose of this study was to determine if there is a difference in these outcomes when a low concentration of patient-controlled epidural bupivacaine combined with fentanyl is compared with ropivacaine combined with fentanyl. Methods This was a multicenter, randomized, controlled trial, including term, nulliparous women undergoing induction of labor. For the initiation of analgesia, patients were randomized to receive either 15 ml bupivacaine, 0.1%, or 15 ml ropivacaine, 0.1%, each with 5 &mgr;g/ml fentanyl. Analgesia was maintained with patient-controlled analgesia with either local anesthetic, 0.08%, with 2 &mgr;g/ml fentanyl. The primary outcome was the incidence of operative delivery. We also examined other obstetric, neonatal, and analgesic outcomes. Results There was no difference in the incidence of operative delivery between the two groups (148 of 276 bupivacaine recipients vs. 135 of 279 ropivacaine recipients;P = 0.25) or any obstetric or neonatal outcome. The incidence of motor block was significantly increased in the bupivacaine group compared with the ropivacaine group at 6 h (47 of 93 vs. 29 of 93, respectively;P = 0.006) and 10 h (29 of 47 vs. 16 of 41, respectively;P = 0.03) after injection. Satisfaction with mobility was higher with ropivacaine than with bupivacaine (mean ± SD: 76 ± 23 vs. 72 ± 23, respectively;P = 0.013). Satisfaction for analgesia at delivery was higher for bupivacaine than for ropivacaine (mean ± SD: 71 ± 25 vs. 66 ± 26, respectively;P = 0.037). Conclusions There was no difference in the incidence of operative delivery or neonatal outcome among nulliparous patients who received low concentrations of bupivacaine or ropivacaine for labor analgesia.

A survey of the management of spinal-induced hypotension for scheduled cesarean delivery

BACKGROUND Intravenous fluids and vasopressors are used for managing spinal-induced hypotension during cesarean delivery, but the choice of vasopressor and the type and timing of fluid administration remain controversial. METHODS We conducted an electronic survey of all members of the Society for Obstetric Anesthesia and Perinatology between February and March 2007 to determine their preferences for preventing and treating spinal-induced hypotension with respect to fluid and vasopressor administration. RESULTS The response rate was 292/746 (39%). Fifty percent worked in academic institutions and 56% had >50% of their clinical responsibility to obstetric anesthesia. For prophylaxis, 35% used fluid preloading, 30% fluid preloading with vasopressors, and 12% fluid co-loading with vasopressors. Of those using vasopressors for prophylaxis, 32% used ephedrine, 26% used phenylephrine, and 33% based their choice on heart rate. For treatment, 32% used ephedrine, 23% used phenylephrine, and 41% used either agent based on heart rate. Anesthesiologists in academic practice were less likely to use fluid preloading only (P=0.028) and more likely to use fluid co-loading and vasopressors (P=0.003). They were also more likely to administer phenylephrine for prophylaxis compared with those in private practice (P=0.042). CONCLUSION Significant variations in practice exist in the prevention and treatment of spinal-induced hypotension. Fluid preloading and the prophylaxis and treatment of hypotension with ephedrine continue to be common practices.

A retrospective assessment of the incidence of respiratory depression after neuraxial morphine administration for postcesarean delivery analgesia.

Respiratory depression can occur after neuraxial morphine administration. In the obstetric population, there are little data on respiratory depression after neuraxial morphine administration in women undergoing cesarean delivery. In this single-center, retrospective study in 5036 obstetric patients (mean body mass index = 34 kg/m2) who underwent cesarean delivery and received neuraxial morphine, we did not identify any instances of respiratory depression requiring naloxone administration or rapid response team involvement. Therefore, the upper 95% confidence limit for respiratory depression in our study is 0.07% (1 event per 1429 cases).

Use of a modifier reduces inconsistency in the American Society of Anesthesiologists Physical Status Classification in parturients.

In this study, we sought to determine whether there is a significant discrepancy among a group of practitioners when rating pregnant patients using the ASA Physical Status Classification and whether this discrepancy could be resolved with the addition of a modifier for pregnancy. Our results indicate that significant discrepancy occurs and that it is reduced with the use of the modifier, especially when referring to the healthy parturient.

Intrathecal morphine for analgesia after postpartum bilateral tubal ligation

Postpartum bilateral tubal ligation (PPBTL) causes postoperative pain. We designed this study to determine the efficacy of 50 &mgr;g intrathecal morphine for analgesia after PPBTL. Sixty-five women received spinal anesthesia with 12.75 mg hyperbaric bupivacaine, 20 &mgr;g of fentanyl, and either 50 &mgr;g of morphine (morphine group) or 0.05 mL of saline (control group). Postoperative analgesia was provided with regular naproxen 500 mg and oxycodone 5 mg/acetaminophen 325 mg mixture as needed. Overall, satisfaction was higher (P = 0.003) and pain was less intense at rest (P = 0.008) and on movement (P < 0.0001) in the morphine group. There was no significant overall difference in nausea, pruritus, or sedation scores, but vomiting occurred more frequently in the morphine group (21.4% versus 3.5%; P = 0.052). In post hoc comparisons, pain at rest within the morphine group was significantly less at 4 h (P = 0.006), pain on movement was significantly less at 4 h (P = 0.002) and 12 h (P = 0.0004), and pruritus was significantly more frequent at 12 h (P = 0.002) compared with the control group. Oxycodone 5 mg/acetaminophen 325 mg mixture consumption was significantly smaller (P = 0.006) and the time to first request of analgesia was significantly longer (P = 0.006) in the morphine group. We conclude that the addition of 50 &mgr;g of morphine to intrathecal hyperbaric bupivacaine and fentanyl provides improved postoperative analgesia in women undergoing PPBTL.

A prospective evaluation of the incidence of adverse events in nurse-administered moderate sedation guided by sedation scores or Bispectral Index.

BACKGROUND:Moderate sedation is routinely performed in patients undergoing minor therapeutic and diagnostic procedures outside the operating room. The level of sedation is often monitored by sedation nurses using clinical criteria, such as sedation scores. The Bispectral Index (BIS) is derived from changes in the electroencephalograph profile that may provide an objective measure of the level of sedation. In this prospective observational study, we investigated whether using BIS values to guide sedative drug administration influences the level of sedation and the incidence of adverse events compared with using Ramsay sedation scale (RSS) only in nurse-administered moderate sedation. We hypothesized that both depth of sedation and the incidence of adverse events related to oversedation would decrease when sedation nurses used BIS values to help guide sedative drug administration. METHODS:Sedation care was provided by trained sedation nurses under the supervision of a physician performing the procedure. The sedation regimen was initiated with IV midazolam 1 to 2 mg and fentanyl 50 mcg or hydromorphone 0.2 mg. Additional small boluses of midazolam, fentanyl, or hydromorphone were administered to maintain an RSS of 2 to 3 (cooperative, oriented, and responding to verbal command). Propofol was not used. Information including patient demographics, type of procedure, medication administered, RSS, and rates of adverse events was recorded by the sedation nurses for each patient on a computer-readable form. The study was divided into 3 phases. In phase 1 (baseline, 6 months’ duration), baseline data on sedation practice were prospectively collected. There was no change from standard of care for all patients except that each patient had a BIS sensor attached, but the monitor was covered and nurses were blinded to the BIS values. In phase 2 (training, 3 months), the sedation nurses received comprehensive education on the use of BIS to guide sedative drug administration, pharmacology of commonly used drugs, and methods for rescue from oversedation. The recommended BIS range for moderate sedation was 75 to 90. Adequate training of all sedation nurses on the use of BIS was documented. In phase 3 (implementation, 6 months), the BIS values were used to guide drug administration. RESULTS:Data were available on 1766 patients (999 and 767 patients in phases 1 and 3, respectively). Most of the procedures were colonoscopies, upper gastrointestinal endoscopies, examinations under anesthesia, endoscopic retrograde cholangiopancreatography, and central venous access catheter placements. No differences in the demographics between the 2 groups were observed. The RSS was inversely associated with the BIS value, r = −0.16 (95% confidence interval, −0.19 to −0.12; P < 0.00001). An RSS of 2 to 3 was maintained in 94% of patients in phase 1 and 96% of patients in phase 3 The mean (±SD) BIS values were 80.9 ± 6.8 in phase 1 and 80.4 ± 6.5 in phase 3. The number of sedation-related adverse events was lower in our sample when BIS was used, with an odds ratio of 0.41 (95% confidence interval, 0.28–0.62; P < 0.0001), and patients with restlessness had a lower BIS value than those without this symptom (P < 0.0001). No serious adverse events or deaths were reported. CONCLUSIONS:Nurse-administered moderate sedation using midazolam and fentanyl was usually associated with appropriate levels of sedation as assessed by both the RSS and BIS with an overall low incidence of adverse events. The use of BIS did not change the mean level of sedation significantly, although the number of sedation-related adverse events appears to be lower when BIS was used.