Cecilia E. Ocampo

A comparison of a basal infusion with automated mandatory boluses in parturient-controlled epidural analgesia during labor.

BACKGROUND:The use of parturient-controlled epidural analgesia (PCEA) with a basal infusion is commonly used in laboring women. We compared a novel approach of providing basal intermittent boluses concurrently with PCEA: PCEA plus automated mandatory boluses (PCEA+AMB) versus PCEA plus basal continuous infusion (PCEA+BCI). We hypothesized that epidural local anesthetic consumption would be lower if basal intermittent boluses were used instead of a basal infusion. METHODS:We randomized 42 healthy parturients in early labor to receive 0.1% ropivacaine + fentanyl 2 &mgr;g/mL either via PCEA+BCI (n = 21,bolus 5 mL, lockout 10 min, basal infusion 5 mL/h) or via PCEA+AMB (n = 21, patient-activated bolus of 5 mL, lockout 10 min, basal automated boluses of 5 mL/h [omitted if a patient-activated bolus was successfully administered in the last 1 h]) after successful induction of combined spinal epidural analgesia. RESULTS:We found a reduction in the hourly consumption of ropivacaine with PCEA+AMB, i.e., the primary outcome measure (mean = 6.5 mL, sd = 3.4 in the PCEA+AMB group vs 7.5 mL, sd = 2.0 PCEA+BCI group, P = 0.011). A larger proportion of parturients in the PCEA+AMB group did not self-bolus (6/21 vs 1/21 in PCEA+BCI, P = 0.03). The time to the first self-bolus after combined spinal epidural was longer in the PCEA+AMB group (mean survival time 315 min vs 190 min in PCEA+BCI group, P = 0.04 by log rank test). There was no difference in pain scores or side effects. CONCLUSION:Our study showed that PCEA+AMB reduced analgesic consumption and could be useful as the mode of maintenance for epidural analgesia.

Combined spinal epidural causes higher level of block than equivalent single-shot spinal anesthesia in elective cesarean patients

Combined spinal epidural (CSE) is an established technique for lower segment cesarean delivery. In this study we tested the hypothesis that the spinal block from a CSE technique results in a more extensive spread of local anesthetic in the subarachnoid space than the single-shot spinal (SSS) technique. We recruited 30 ASA physical status I parturients admitted for elective lower segment cesarean delivery into our randomized, controlled, double-blind study. All patients intrathecally received 2 mL of 0.5% hyperbaric bupivacaine. The patients were randomized into one of the two groups using sealed opaque envelopes. Group S (n = 15) received a SSS technique. Group CS (n = 15) received a CSE technique using loss of resistance to 2 mL of air, but the epidural catheter was not inserted after the intrathecal drug administration. The maximal sensory block achieved in group CS was statistically higher than that in Group S (median C6 interquartile range, C5 to C8 versus median T3, T2 to T4, P < 0.001). Time taken to reach maximal sensory block was significantly longer in group CS. There were no differences in the time taken for the block to recede to T10, hemodynamic profile, or side effects. In conclusion, the CSE technique without placing an epidural catheter or administering epidural medication resulted in a significantly higher level of sensory block when compared with the SSS technique when the same dose of local anesthetic was given intrathecally.

A randomised trial of the analgesic efficacy of ultrasound-guided transversus abdominis plane block after caesarean delivery under general anaesthesia.

Context Previous studies examining the efficacy of transversus abdominis plane block after caesarean section have mostly been in parturients under spinal anaesthesia. Objectives We postulated that the advantage of performing transversus abdominis plane block after caesarean section might be even more obvious after general anaesthesia, resulting in reduced 24-h consumption of morphine. Design, setting, patients and interventions In this single centre, randomised double-blind controlled trial, 40 women who underwent caesarean delivery under general anaesthesia were allocated randomly to receive a transversus abdominis plane block or no block. In those who received the block, 20 ml of levobupivacaine 2.5 mg ml−1 was deposited bilaterally into the transversus abdominis plane under ultrasound guidance using a Sonosite Titan (SonoSite, Bothell, Washington, USA) 7–13 MHz linear transducer at the end of surgery when the patient was still anaesthetised. Main outcome measures We recorded patient-controlled intravenous morphine use for 24 h, pain scores at rest and activity, sedation, nausea and vomiting, use of antiemetic medication and overall maternal satisfaction. The primary outcome was 24-h morphine consumption. Results Patients who received the transversus abdominis plane block used significantly less morphine in 24 h than those in the control group [12.3 (2.6) vs. 31.4 mg (3.1), P < 0.001) and had higher satisfaction scores [16 (80%) vs. 5 (25%), P = 0.012). There were no differences between groups in the visual analogue pain scores, sedation level, nausea and vomiting or the use of antiemetic medication. Conclusion Ultrasound-guided transversus abdominis plane block reduced morphine consumption following caesarean section under general anaesthesia, with increased maternal satisfaction.

A randomized comparison of automated intermittent mandatory boluses with a basal infusion in combination with patient-controlled epidural analgesia for labor and delivery

BACKGROUND Automated mandatory boluses (AMB), when used in place of a continuous basal infusion, have been shown to reduce overall local anesthetic consumption without compromising analgesic efficacy in patient-controlled epidural analgesia (PCEA). We hypothesized that our PCEA+AMB regimen could result in a reduction of breakthrough pain requiring epidural supplementation in comparison with PCEA with a basal infusion (PCEA+BI). METHODS We recruited sixty-two healthy ASA I nulliparous parturients in early labor. The parturients were randomized to receive 0.1% ropivacaine+fentanyl 2 μg/mL either via PCEA+BI (PCEA with basal continuous infusion of 5mL/h) or PCEA+AMB (PCEA with AMB of 5 mL every hour instead of a basal infusion) immediately following successful induction of combined spinal-epidural (CSE) analgesia. Block characteristics, incidence of breakthrough pain requiring epidural supplementation, side effects, obstetric outcomes, Apgar scores and overall maternal satisfaction with analgesia were noted. RESULTS The time-weighted hourly consumption of ropivacaine (PCEA and clinician supplementation for breakthrough pain) was significantly lower in the PCEA+AMB group (mean=7.6 mL, SD 3.2) compared to the PCEA+BI group (mean=9.3 mL, SD 2.5; P<0.001). The mean time to first PCEA self-bolus following CSE was significantly longer in the PCEA+AMB group compared to the PCEA+BI group (268 min vs. 104 min; P<0.001). Parturients in Group PCEA+AMB also gave higher satisfaction scores. The incidence of breakthrough pain was similar in both groups. CONCLUSION PCEA+AMB, when compared to PCEA+BI, confers greater patient satisfaction and a longer duration of effective analgesia after CSE despite reduced analgesic consumption.

A randomized controlled trial of three patient-controlled epidural analgesia regimens for labor.

BACKGROUND:Patient-controlled epidural analgesia (PCEA) is a safe and effective mode of maintaining labor analgesia; however, the ideal PCEA regimen is controversial. METHODS:In this prospective, randomized, double-blind study, we examined the analgesic efficacy of demand-only PCEA and PCEA with background infusion. We recruited 300 nulliparous parturients. Analgesia was initiated with intrathecal ropivacaine 2 mg and fentanyl 15 μg and maintained with epidural ropivacaine 0.1% with fentanyl 2 μg/mL. Parturients were randomized to one of three groups. Group 0: demand-only PCEA, bolus of 5 mL, lockout interval of 15 min. Group 5: background infusion of 5 mL/h, bolus of 5 mL, lockout interval of 12 min. Group 10: background infusion of 10 mL/h, bolus of 5 mL, lockout interval of 10 min. The maximum dose of all groups was 20 mL/h. The primary outcome was incidence of breakthrough pain. Secondary outcomes included intrapartum pain scores, neuraxial blockade characteristics, side effects, the total and hourly volume of ropivacaine, neonatal outcomes, and obstetric outcomes. RESULTS:The incidence of breakthrough pain and the maximum visual analog scale (0–100 mm scale) pain scores were higher in Group 0 versus Groups 5 and 10 (43% vs 17% and 11%, P < 0.001 and 37 ± 28 vs 22 ± 26 and 16 ± 25 [mean ± sd], P < 0.001), respectively. Group 10 had a longer duration of effective analgesia compared with Group 0 (mean 895 min, 95% CI 823–966 vs 565 min, 95% CI 454–677, P < 0.001) and increased ropivacaine consumption, and was associated with a longer duration of the second stage of labor. CONCLUSION:Demand-only PCEA (5-mL bolus, 15-min lockout interval) resulted in less local anesthetic consumption but an increased incidence of breakthrough pain, higher pain scores, shorter duration of effective analgesia, and lower maternal satisfaction, when compared with PCEA with background infusion (5-mL bolus, 10–12-min lockout interval, and 5–10 mL/h infusion).

A comparison of median effective doses of intrathecal levobupivacaine and ropivacaine for labor analgesia.

Background:The study was designed to determine and compare the median effective doses (MEDs) of intrathecal ropivacaine with levobupivacaine for labor analgesia. Methods:In this double-blind study, 100 parturients in early labor were randomized to receive either intrathecal ropivacaine or levobupivacaine. For each drug, the patients were assigned to receive one of the five doses studied, namely 1, 1.5, 2, 2.5, or 3 mg. Effective analgesia was defined as a pain score (0–100 visual analog scale) of less than 10 within 15 min of injection, lasting for 45 min or more after the induction of analgesia. MEDs were derived from probit analysis. The duration of analgesia rendered by the two drugs at 2.5 and 3 mg was also compared. Results:The MED for levobupivacaine was 1.07 mg (95% confidence interval, 0.88–1.25 mg), and the MED for ropivacaine was 1.40 mg (95% confidence interval, 1.20–1.61 mg). Levobupivacaine was found to be 1.31 (95% confidence interval, 1.04–2.01) times more potent than ropivacaine. At doses of 2.5 mg or greater, there was no significant difference in duration of analgesia between levobupivacaine (median, 63.5 min; range, 46–123 min) and ropivacaine (median, 59.0 min; range, 47–93 min; P = 0.18). We detected no difference in the incidence of hypotension, nausea and vomiting, motor block, or abnormal fetal heart tracing between the two drugs. Conclusions:The MED of intrathecal ropivacaine for labor analgesia was significantly greater than levobupivacaine experimentally, but this significance was reduced when the comparison was based on molar potency. There was no difference in the duration of analgesia or adverse effects between the two drugs at higher doses (2.5 mg or greater).

Influence of Mu-Opioid Receptor Variant on Morphine Use and Self-Rated Pain Following Abdominal Hysterectomy

UNLABELLED A common variant in the mu-opioid receptor gene (OPRM1) has been associated with response to opioid analgesia. Our previous data revealed significantly higher amounts of morphine self-administered by patients carrying the 118G allele compared to those with the 118A allele after elective cesarean section. In this study, the association of this genetic variation with pressure pain, postoperative pain scores, and amount of morphine used was investigated in 973 patients undergoing scheduled total hysterectomy under general anesthesia. Preoperative pressure pain threshold and tolerance were also measured for most patients. For pressure pain, OPRM1 genotype was not significantly associated with either pain threshold or pain tolerance. Statistically significant associations were found for postoperative pain and the total amount of morphine used, with the GG group reporting higher pain scores and using the most morphine. When analysis was stratified by ethnic group, differences in weight-adjusted morphine for the 3 genotypic groups were also significant for the Chinese and Asian Indians. These results extend our previous finding on the association of higher self-reported pain and morphine use for acute postoperative pain with OPRM1 118G to patients who had total hysterectomy under general anesthesia. PERSPECTIVE In a large cohort of patients undergoing hysterectomy, we found large variability in the self-rated pain scores and the amount of morphine required for pain relief. Both are associated with OPRM1 genotypes and preoperative experimental pressure pain threshold. Experimental pressure pain tolerance is also associated with postoperative pain.

A randomised comparison of variable-frequency automated mandatory boluses with a basal infusion for patient-controlled epidural analgesia during labour and delivery.

This trial was conducted to compare the analgesic efficacy of administering variable‐frequency automated boluses at a rate proportional to the patients needs with fixed continuous basal infusion in patient‐controlled epidural analgesia (PCEA) during labour and delivery. We recruited a total of 102 parturients in labour who were randomly assigned to receive either a novel PCEA with automated mandatory boluses of 5 ml administered once, twice, three or four times per hour depending on the history of the parturients analgesic demands over the past hour (Automated bolus group), or a conventional PCEA with a basal infusion of 5 ml.h−1 (Infusion group). The incidence of breakthrough pain requiring supplementation by an anaesthetist was significantly lower in the Automated bolus group, three out of 51 (5.9%) compared with the Infusion group, 12 out of 51 (23.5%, p = 0.023). The time‐weighted mean (SD) hourly consumption of ropivacaine was similar in both groups, 10.0 (3.0) mg in the Automated bolus group vs 11.1 (3.2) mg in the Infusion group (p = 0.06). Parturients from the Automated bolus group reported higher satisfaction scores compared with those in the Infusion group, 96.5 (5.0) vs 89.2 (9.4), respectively (p < 0.001). There was no difference in the incidence of maternal side‐effects and obstetric and neonatal outcomes.

0.2% ropivacaine and levobupivacaine provide equally effective epidural labour analgesia

PurposeTo compare the duration of epidural analgesia induced by levobupivacaine and ropivacaine at clinically relevant doses.MethodsForty healthy nulliparous parturients with cervical dilatation of 3 to 5 cm and at least one contraction every two or three minutes were recruited. Patients were randomly assigned to receive either 10 mL of 0.2% ropivacaine or 10 mL of 0.2% levobupivacaine. Preblock visual analogue scale (VAS) score (0–100) and VAS score after five, ten, 15, 20, 25 and 30 min from time0 and VAS at time of request for additional analgesia (timeend) were recorded. During the first 30 min after the completion of epidural injection, the systolic blood pressure, highest sensory level to cold and the maximum degree of motor block based on a 0 to 3 modified Bromage scale were collected every five minutes. The duration of analgesia was defined as the time from time0 to timeend.ResultsThere was no difference in the duration of analgesia between the two groups; similarly, there was no significant difference found in the area under the curve (AUC) time15-time0 and AUC time30-time0 for VAS. The highest sensory block to cold and the degree of motor block were also indistinguishable between the two groups. No difference in the serial systolic blood pressures was found.ConclusionTen millilitres of either 0.2% ropivacaine or levobupivacaine can be used to induce epidural labour analgesia effectively without a difference in the duration of pain relief.RésuméObjectifComparer la durée de l’analgésie péridurale induite par la lévobupivacaïne et la ropivacaïne administrées selon les doses cliniques appropriées.MéthodeQuarante parturientes nullipares en bonne santé, chez qui la dilatation cervicale était de 3 à 5 cm et les contractions aux 2 ou 3 minutes, ont participé à l’étude. Elles ont été réparties au hasard pour recevoir soit 10 mL de ropivacaïne à 0,2 %, soit 10 mL de lévobupivacaïne à 0,2 %. Les scores préanalgésiques à l’échelle visuelle analogique (EVA) de 0–100, puis les scores à 5, 10, 15, 20, 25 et 30 min du temps0 et au moment de la demande d’analgésiques supplémentaires (tempsfinal) ont été enregistrés. Pendant les 30 premières minutes suivant l’injection péridurale, la tension artérielle systolique, le plus haut niveau sensitif au froid et le degré maximal de bloc moteur, à l’échelle de Bromage modifiée de 0 à 3, ont été notés toutes les cinq minutes. La durée de l’analgésie a été déterminée comme le temps écoulé entre le temps0 et le tempsfinalRésultatsLa durée de l’analgésie a été similaire dans les deux groupes; de même, il n’y a pas eu de différence significative pour l’aire sous la courbe (ASC) du temps15-temps0 et de l’ASC du temps30-temps0. Le plus haut bloc sensitif au froid et le degré de bloc moteur, de même que la série de tensions artérielles systoliques étaient similaires dans les deux groupes.ConclusionDix millilitres de ropivacaïne ou de lévobupivacaïne à 2 % peuvent induire efficacement l’analgésie péridurale du travail et produire la même durée d’analgésie.

Incidence and characteristics of breakthrough pain in parturients using computer-integrated patient-controlled epidural analgesia

INTRODUCTION The computer-integrated patient-controlled epidural analgesia (CIPCEA) system can automatically adjust the background infusion rate during combined spinal-epidural analgesia based on the parturients need, as labor progresses. OBJECTIVES The objective is to identify risk factors associated with breakthrough pain during labor as well as identify obstetric and fetal outcomes that are affected by breakthrough pain. DESIGN This is a retrospective review of prospectively collected data. SETTING The setting is in a delivery room. PARTICIPANTS The participants are 280 nulliparous women in early labor (≤5 cm cervical dilatation) who received combined spinal-epidural analgesia with CIPCEA. INTERVENTIONS The intervention is CIPCEA. MEASUREMENTS The primary outcome is the incidence of breakthrough pain (≥1 episodes of pain or pressure that required supplemental epidural medications) during labor. Relevant demographic, anesthetic, obstetric, and fetal characteristics were also measured. Univariate and multivariate analyses were performed to identify obstetric and anesthetic factors that were associated with increased incidence of breakthrough pain as well as to evaluate the impact of breakthrough pain on obstetric and fetal outcomes. RESULTS The incidence of breakthrough pain was 9.6%. Independent factors associated with incidence of breakthrough pain are the presence of dysfunctional labor, increased maternal body mass index, and decreased successful-to-total-bolus-demand ratio. The postlabor characteristics independently associated with breakthrough pain were increased duration of labor, decreased duration of effective analgesia, increased total local anesthetic consumption, and decreased maternal satisfaction. CONCLUSIONS Low successful to total patient demand bolus ratio was the factor with the strongest association with breakthrough pain. Breakthrough pain was also associated with dysfunctional labor and poorer maternal satisfaction.