Modern neuraxial labour analgesia.

PURPOSE OF REVIEW: Neuraxial analgesia is considered the gold standard of labour analgesia as it provides the most effective method of pain relief during childbirth. In this article, we explore the recent advances in the initiation and maintenance of epidural analgesia. RECENT FINDINGS: Patient-controlled epidural analgesia, computer-integrated patient-controlled epidural analgesia, intermittent epidural bolus (programmed intermittent bolus, automated mandatory bolus) and variable frequency automated mandatory bolus administration are techniques that allow the individualized titration and optimization of labour analgesia. The debate has moved on to finding the optimal settings for epidural bolus dosing, time intervals and frequency for epidural analgesia with the hope of improving safety and efficacy as well as patient satisfaction. SUMMARY: We examine these recent developments in pump technology and epidural delivery systems and evaluate how these have enhanced the mothers' birthing experiences.

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 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.

The ongoing challenges of regional and general anaesthesia in obstetrics.

The increasing trend of caesarean section in the setting of increasing maternal age, obesity and other concomitant diseases will continue to challenge the obstetric anaesthetist in his/her task of providing regional and general anaesthesia. The challenges of providing anaesthesia for an emergency caesarean section, particularly the risks of general anaesthesia, will be debated. The need for involvement of a multidisciplinary team, good communication and challenges surrounding the provision of anaesthesia to such patients are discussed.

A randomized comparison of low doses of hyperbaric bupivacaine in combined spinal-epidural anesthesia for cesarean delivery.

BACKGROUND: The aim of our study was to investigate the block characteristics of intrathecal hyperbaric bupivacaine 7, 8, or 9 mg administered during combined spinal-epidural anesthesia for cesarean delivery and to elucidate the dose that produces adequate sensory blockade for surgery while minimizing the incidence of hypotension, high neuroblockade, and the need for intraoperative epidural supplementation. METHODS: Sixty women presenting for elective cesarean delivery were randomly assigned to one of the 3 groups. Group 7 received intrathecal hyperbaric bupivacaine 7 mg, Group 8 received 8 mg, and Group 9 received 9 mg. Women in all 3 groups received intrathecal morphine 100 microg and IV hydroxyethyl starch 15 mL/kg at the time of initiation of combined spinal-epidural anesthesia. Surgery began when a sensory level of T4 was achieved. Patients were monitored for block characteristics and side effects by a blinded observer. Our primary outcome was the maximum cephalad sensory block height. RESULTS: There was a difference in the maximum extent of cephalad sensory block among groups (Group 7: median T2 [interquartile range T2-T3]; Group 8: median T2 [T1-T2]; Group 9: median T1 [C8-T2]; P = 0.02). However, the time taken to reach T4 was similar in all 3 groups. The incidence of hypotension requiring vasopressors was different among groups (30% in Group 7, 55% in Group 8, and 70% in Group 9; P = 0.04). No patient had inadequate anesthesia. Neonatal outcomes were similar in all 3 groups. CONCLUSION: The lowest dose of hyperbaric bupivacaine (7 mg) provided equally rapid onset and effective anesthesia for cesarean delivery while reducing the incidence of hypotension compared with 8 and 9 mg. However, because of its shorter duration of anesthesia, it may be feasible only when the block can be reinforced using a functional epidural catheter.

Colloid preload versus coload for spinal anesthesia for cesarean delivery: the effects on maternal cardiac output.

BACKGROUND: Spinal anesthesia for cesarean delivery may cause severe maternal hypotension, and a decrease in cardiac output (CO) and blood flow to the placenta. Fluid preloading with crystalloid is ineffective due to rapid redistribution. A "coload" given at the time of cerebrospinal fluid identification may be more effective. Our null hypothesis was that there would be no difference between the effect of a colloid preload (15 mL/kg hydroxyethyl starch (HES) 130/0.4 [Voluven 6%]) and an identical coload on maternal CO and the incidence of hypotension after spinal anesthesia for cesarean delivery. Secondary outcomes studied were neonatal acid- base status and predelivery vasopressor requirements. METHODS: Forty ASA PS I and II women scheduled for elective cesarean delivery were recruited. Patients were randomized to Group P (preload of 15 mL/kg HES) or Group C (coload, given when cerebrospinal fluid identified). Heart rate, arterial blood pressure, stroke volume and CO measurements were recorded at baseline, every minute for 10 min, and every 2.5 min interval for 10 min with the USCOM ultrasonic CO monitor. Spinal anesthesia was performed at the L3/4 interspace in the right lateral position. Arterial blood pressure was maintained at 90%-100% of baseline values using IV phenylephrine boluses. RESULTS: Demographic, anesthetic, and surgical characteristics were similar. There were no between-group differences in baseline systolic blood pressure, heart rate, and colloid volume. CO and stroke volume were significantly increased in Group P (P = 0.01) in the 5 min after spinal anesthesia. This increase in CO was not sustained at 10 min. There were no significant between-group differences in the incidence of hypotension, absolute arterial blood pressure values (P = 0.73), predelivery median (range) phenylephrine requirements (300[0-1000] in Group P versus 150 [0-850]microg in Group C, P = 0.24), or neonatal outcome as measured by Apgar scores and umbilical arterial and venous blood gas values. CONCLUSION: Intravascular volume expansion with 15 mL/kg HES 130/0.4 given as a preload, but not coload, significantly increased maternal CO for the first 5 min after spinal anesthesia for cesarean delivery, however, maternal and neonatal outcomes were not different.

0.2% Ropivacaine and levobupivacaine provide equally effective epidural labour analgesia.

PURPOSE: To compare the duration of epidural analgesia induced by levobupivacaine and ropivacaine at clinically relevant doses. METHODS: Forty 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 time(0) and VAS at time of request for additional analgesia (time(end)) 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 time(0) to time(end). RESULTS: There 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) time(15)-time(0) and AUC time(30)-time(0) 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. CONCLUSION: Ten 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.

Automated intermittent epidural boluses improve analgesia induced by intrathecal fentanyl during labour.

PURPOSE: We compared the efficacy of epidural continual intermittent boluses (CIB) with a continuous epidural infusion (CEI) in prolonging labour analgesia induced by the combined spinal epidural (CSE) technique. METHODS: CSE was instituted in 42 nulliparous parturients at the L3 to 4 level with intrathecal (IT) fentanyl 25 micro g followed by an epidural test dose of 3 mL of 1.5% lidocaine. These parturients were then randomly assigned to receive either epidural CIB (n = 21) or CEI (n = 21) with 0.1% ropivacaine and fentanyl 2 micro g x mL(-1). For the CIB, 5 mL boluses were given hourly, with the first bolus 30 min postinduction. CEI at the rate of 5 mL.hr(-1) was initiated in the minute after CSE. The duration of analgesia, pain score, degree of sensorimotor block were compared. RESULTS: From Kaplan Meier survival analysis, the duration of analgesia was significantly longer in CIB (mean survival time 239 +/- SD 24 min vs 181 +/- 17, P < 0.05 using log rank test). During the first three hours postblock, the median sensory block to cold was higher in CIB (P < 0.05, Mann U Whitney test) but no difference in blood pressure was detected [P > 0.05, repeated measure analysis of variance (RMANOVA)]. The serial pain scores were lower in the CIB (P < 0.05, RMANOVA). CONCLUSION: CIB prolonged the duration and improved the quality of analgesia. CIB could have resulted in an improved spread of analgesics in the epidural space or encouraged a direct passage of infusate into the IT space. This could have also rendered a higher sensory block to cold in the CIB group. CIB is a good alternative to CEI for the maintenance of epidural analgesia after CSE.

Hyperbaric bupivacaine 2.5 mg prolongs analgesia compared with plain bupivacaine when added to intrathecal fentanyl 25 microg in advanced labor.

We investigated the effect of sequential administration of intrathecal (IT) hyperbaric bupivacaine (after the initial administration of IT hypobaric fentanyl) on the duration of spinal analgesia. Thirty-seven nulliparous parturients with a cervical dilation >/= 5 cm were randomized to receive either IT fentanyl 25 micro g and plain bupivacaine 2.5 mg (group P; n = 19) or IT fentanyl 25 micro g and hyperbaric (with 8% glucose) bupivacaine 2.5 mg (group H; n = 18). The two components of the IT injectate were administered sequentially (fentanyl 25 micro g diluted in 2 mL of normal saline, immediately followed by 0.5 mL of 0.5% bupivacaine). Patients were then positioned with their torso elevated at 30 degrees for 30 min. Pain scores using 0-100 visual analog scales were collected before combined spinal/epidural analgesia and at 5, 15, and 30 min after the block. Patients in Group H had a longer median duration of analgesia (122 min; range, 80-210 min) than Group P (95 min; range, 75-125 min) (P < 0.01). Group H also had a more limited dermatomal spread (median highest sensory level of T8 versus T4 in group P; P < 0.05). The side-effect profile was similar. Under these circumstances, hyperbaric bupivacaine conferred an increased duration of IT analgesia compared with plain bupivacaine.

Addition of bupivacaine 1.25 mg to fentanyl confers no advantage over fentanyl alone for intrathecal analgesia in early labour.

PURPOSE: a) To evaluate the effect of adding 1.25 mg of bupivacaine to intrathecal fentanyl on the duration of analgesia in an Asian population and b) to examine if the baricity of the local anesthetic at this dose has any bearing on the duration and quality of block. METHODS: Forty-eight parturients in early labour received combined spinal epidural (CSE) analgesia to evaluate a) the effect of adding 1.25 mg of bupivacaine to intrathecal (IT) fentanyl 25 microg on the duration of analgesia and b) the effect of baricity of intrathecal local anesthetic on the duration and quality of the block. Patients were randomly allocated to receive: IT fentanyl 25 microg plus normal saline (Group f, n=16), IT fentanyl 25 microg plus plain bupivacaine 1.25 mg (Group f+pb, n=16) and IT fentanyl 25 microg plus heavy bupivacaine 1.25 mg (Group f+hb, n=16). The two components of the IT injectate (total of 2.25 mL) were given sequentially. RESULTS: Group f+hb had the lowest sensory dermatomal block (T7 vs T4 (Group f), T5 (Group f+pb), P <0.01). There were no differences in the duration of analgesia and incidence of side effects among the groups. CONCLUSION: We found no advantage of adding 1.25 mg bupivacaine to fentanyl 25 microg. At this dose, the baricity of bupivacaine has no effect on the duration of analgesia.