Does epidural versus combined spinal-epidural analgesia prolong labor and increase the risk of instrumental and cesarean delivery in nulliparous women?

STUDY OBJECTIVE: To compare duration of labor, mode of delivery, and local anesthetic consumed in women who received labor analgesia with epidural or combined spinal-epidural technique. DESIGN: Retrospective, observational study. SETTING: Delivery room of a university hospital. PATIENTS: 788 nulliparous women in labor at term with cervical dilation between three and 5 cm. INTERVENTIONS: In Group E (epidural alone), parturients received an epidural solution of 8 mL (levobupivacaine 0.125% with fentanyl 5 microg/mL). In Group CSE (combined spinal-epidural), parturients received a spinal injection of levobupivacaine two mg with fentanyl 15 microg (total volume two mL). Then an epidural catheter was placed in all patients and connected to a patient-controlled analgesia pump (basal infusion rate of 8 mL/hr of 0.1% levobupivacaine and fentanyl two microg/mL, patient-controlled bolus dose of three mL, and lockout time of 30 min). MEASUREMENTS: Labor duration, mode of delivery (spontaneous vaginal vs. instrumental delivery vs. cesarean section), and local anesthetic consumed, were recorded. MAIN RESULTS: Labor analgesia was performed with an epidural technique in 322 patients (40.9%), and a combined spinal-epidural technique in 466 patients (59.1%), of whom 39 Group E women (12.1%) and 46 Group CSE women (9.9%) required cesarean section (P=ns). No differences in the mode of delivery were observed between the groups. Time from analgesia to delivery (Group E: 217 +/- 111 min vs. Group CSE: 213 +/- 115 min; P=ns), and epidural local anesthetic consumed (Group E: 35 +/- 20 mL vs. Group CSE: 33 +/- 20 mL; P=ns), were similar in both groups. CONCLUSIONS: No significant differences were observed between epidural and combined spinal-epidural given for labor analgesia in nulliparous women in duration of labor, mode of delivery, or local anesthetic consumed.

A prospective, randomized comparison between the popliteal and subgluteal approaches for continuous sciatic nerve block with stimulating catheters.

In this prospective, blinded study, we randomized 56 patients undergoing hallux valgus repair to receive continuous sciatic nerve block using a subgluteal (n = 28) or a posterior popliteal approach (n = 28) with a perineural stimulating catheter. Postoperatively, the stimulating catheter was connected to a patient-controlled analgesia pump with 0.0625% levobupivacaine (basal infusion rate of 3 mL/h, patient-controlled bolus dose of 3 mL, and lockout time of 20 min). Both approaches provided similar postoperative analgesia; however, local anesthetic consumption was larger in the popliteal group (4.9 +/- 1.4 mL/h) compared with the subgluteal group (3.8 +/- 1.1 mL/h; P < 0.05). We conclude continuous postoperative analgesia using stimulating catheters was effective at both injection sites; however, a subgluteal approach reduced the overall amount of local anesthetic.

What is the minimum effective volume of local anesthetic required for sciatic nerve blockade? A prospective, randomized comparison between a popliteal and a subgluteal approach.

For sciatic nerve blockade, no study has defined the optimal volume of local anesthetic required to block the nerve. The current, prospective, randomized investigation was designed to find a minimum volume of 1.5% mepivacaine required to block the sciatic nerve using the subgluteal and posterior popliteal approaches. A total of 56 patients undergoing foot surgery were randomly assigned to receive sciatic nerve block by means of a posterior subgluteal (group subgluteal, n = 28) or a posterior popliteal (group popliteal, n = 28) approaches. All blocks were performed with the use a nerve stimulator (stimulating frequency, 2 Hz, intensity 1.5-0.5 mA) and a perineural stimulating catheter. In all patients, plantar flexion of the foot was elicited at <0.5 mA, to maintain consistency among groups. The volume of local anesthetic used in each patient was based on the modified Dixon's up-and-down method. Complete anesthesia was defined as complete loss of pinprick sensation in the sciatic nerve distribution with concomitant inability to perform plantar or dorsal flexion of the foot 20 min after injection. The mean volume of local anesthetic required to block the sciatic nerve was 12 +/- 3 mL in the subgluteal group and 20 +/- 3 mL in the popliteal group (P < 0.05). The ED95 for adequate block of the sciatic nerve was 17 mL in the subgluteal group and 30 mL in the popliteal group. The authors conclude that a larger volume of local anesthetic is necessary to block the sciatic nerve at a more distal site (popliteal approach) as compared with a more proximal level (subgluteal approach).

Stimulating popliteal catheters for postoperative analgesia after hallux valgus repair.

Stimulating catheters have been recently introduced in clinical practice. We assessed the efficacy of stimulating and nonstimulating catheter placement for pain control and local anesthetic requirements after hallux valgus repair with continuous sciatic popliteal nerve block in this comparative, randomized, blinded-to-observer study of 48 patients. A stimulating catheter was placed in groups S-125 and S-0625. The same catheter was inserted without stimulation in group NS-125. An infusion of 0.125% levobupivacaine was given in groups S-125 and NS-125, whereas 0.0625% levobupivacaine was used in group S-0625. All patients received an infusion of the test drug at a basal rate of 3 mL/h, with the possibility of an additional bolus of 3 mL every hour. Verbal analog scale (VAS) scores for pain were assessed between 6-8 h and between 19-23 h postoperatively. Multiple attempts were required for catheter insertion in all patients in groups S-125 and S-0625. Lower median (range) VAS scores for pain (0-100 points) were found in group S-125 at 6-8 h postoperatively when compared with groups S-0625 and NS-125: 5 (0-17.5) versus 60 (15-80) and 70 (25-80), respectively (P < 0.05); and lower VAS scores for pain were also found in group S-125 at 19-23 h when compared with group NS-125: 0 (0-0) and 7.5 (0-10), respectively (P < 0.05). Fewer patients required IV opioid analgesia in group S-125 than in groups S-0625 and NS-125: 0, 5, and 7 patients, respectively (P < 0.05). We conclude that efficacy in pain control was increased with stimulating catheter placement.

Does the site of injection distal to the greater trochanter make a difference in lateral sciatic nerve blockade?

UNLABELLED: The two components of the sciatic nerve become more distant from one another in their course down the lower limb. This may have clinical implications if a small volume of local anesthetic is used with a single injection technique. In this prospective, randomized, double-blind study, we compared two different injection sites, 20 cm and 30 cm distal to the greater trochanter, in terms of onset time and success rate of sciatic nerve blockade after a single injection of 20 mL of 1.5% mepivacaine. Fifty patients undergoing foot surgery were randomly allocated to receive a lateral sciatic nerve blockade using one of 2 levels: 20 cm distal to the greater trochanter (group proximal; n = 25) and 30 cm distal to the greater trochanter (group distal; n = 25). Twenty milliliters of 1.5% mepivacaine was injected after a flexion plantar response was obtained at <0.5 mA. Time required for onset of sensory and motor blockade of the foot was recorded. Success rate was defined as complete sensory and motor blockade in all sciatic nerve distributions associated with a pain-free surgery. Onset of complete sensory and motor blockade was faster in group proximal (12 +/- 7 min and 15 +/- 8 min, respectively) compared with group distal (19 +/- 9 min and 23 +/- 9 min; P < 0.05). Group proximal also had a more frequent success rate compared with group distal (88% versus 56%, respectively; P < 0.05). It is concluded that in lateral sciatic nerve blockade, a more proximal approach to the sciatic nerve predicts a shorter onset time and more frequent success than a more distal injection site when a single injection and a small volume of local anesthetic is used. IMPLICATIONS: In lateral sciatic nerve blockade, a more proximal approach to the sciatic nerve provides shorter onset times and more frequent success than a more distal injection site when a single injection of 20 mL of mepivacaine 1.5% is used.