Low-dose combined spinal-epidural anesthesia for cesarean delivery: a comparison of three plain local anesthetics.

The new local anesthetics have been poorly studied for intrathecal use during Cesarean section surely in low doses and in combination with an opioid substance. The purpose of the present study was to compare bupivacaine and the newer local anesthetics in equipotent doses. During the induction of combined spinal-epidural anesthesia, 91 elective Cesarean section patients were randomly assigned to receive a spinal injection of either 10 mg ropivacaine or 6.6 mg bupivacaine or levobupivacaine both combined with sufentanil 3.3 microg. After securing the epidural catheter patients were turned to the supine position respecting a 15 degrees left lateral tilt. The three local anesthetics were compared with respect to sensory and motor block, the need for epidural supplementation, the severity of hypotension and neonatal outcome. More patients in bupivacaine had a Bromage-3 motor block at incision. The ropivacaine group required additional local anesthetics by the epidural route in 23% of the cases versus 10% in the bupivacaine group and 9% with levobupivacaine. This caused the interval between the spinal injection and the end of surgery to be longer in the ropivacaine group. Hemodynamic values were comparable between the three groups although a trend towards better systolic blood pressures and a lower incidence of severe hypotension were noticed in favor of levobupivacaine. Apgar scores and umbilical pH values did not differ. When performing a low-dose combined spinal-epidural technique for Cesarean section, the present study confirms that the new local anesthetics can be used successfully, induce less motor block but that ropivacaine requires at least a 50% larger dose than bupivacaine or levobupivacaine.

Prevention of hypotension by a single 5-mg dose of ephedrine during small-dose spinal anesthesia in prehydrated cesarean delivery patients.

UNLABELLED: To evaluate the effectiveness of prophylactic ephedrine for the prevention of hypotension associated with spinal anesthesia, 50 parturients undergoing cesarean delivery received either ephedrine 5 mg or saline IV in a double-blinded fashion immediately after the induction of spinal anesthesia. Spinal anesthesia was performed with hyperbaric bupivacaine 6.6 mg combined with sufentanil 3.3 microg as part of a combined spinal-epidural technique. All patients received 1000 mL of lactated Ringer's solution and 500 mL of hydroxyethylstarch 6% before the spinal injection. Additional ephedrine boluses (5 mg) were administered IV when the systolic blood pressure or heart rate decreased by more than 30% from baseline values, when systolic blood pressure became <100 mm Hg, or when patients complained of nausea or feeling faint. The height of the block was equal in the groups; however, more patients in the placebo group were found to develop hypotension (58% vs 25%, P < 0. 05). Only 2 (8%) patients in the ephedrine group developed hypotension with systolic blood pressure values <90 mm Hg, whereas 10 patients (42%) in the saline group experienced hypotension of this severity (P < 0.05). In addition, there was a higher incidence of nausea in the placebo-treated patients. The total amount of ephedrine administered did not differ between groups. These findings suggest that the incidence and severity of hypotension are significantly reduced by the IV administration of a prophylactic dose of 5 mg ephedrine in patients receiving small-dose spinal anesthesia for cesarean delivery. IMPLICATIONS: Ephedrine is the drug most often used to correct hypotension during spinal anesthesia for cesarean delivery in healthy patients. A single IV dose of 5 mg decreases the occurrence and limits the severity of hypotension in prehydrated subjects receiving a small-dose spinal local anesthetic-opioid combination.

Posterior epidural space depth: safety of the loss of resistance and hanging drop techniques.

We have compared skin to epidural space distance (SED) and tip to tip distance (TTD), a measure of posterior epidural space depth (PESD), in 40 patients with a 27-gauge Whitacre needle after identification of the epidural space using the hanging drop (HD) or loss of resistance (LOR) to air technique. After the LOR technique, TTD was found to be 2 mm greater than that after the HD technique, whereas SED was the same. We conclude that identification of the epidural space can be performed successfully with both techniques, but with a diminished risk of dural damage after LOR compared with the HD technique.

Small-dose hyperbaric versus plain bupivacaine during spinal anesthesia for cesarean section.

UNLABELLED: In a double-blind, randomized trial, 98 parturients undergoing cesarean section received either hyperbaric or plain bupivacaine 6.6 mg combined with sufentanil 3.3 microg as part of a combined spinal-epidural procedure. To prevent hypotension, 1000 mL of lactated Ringer's solution, 500 mL of hydroxyethyl starch 6%, and ephedrine 5 mg were administered i.v. The height of the block was equal in both groups, but more patients in the plain group had blocks that were either too high or too low (P < 0.01). The number of patients requiring epidural supplementation was equal in both groups. Strict criteria were used to treat hypotension. The overall incidence of systolic blood pressure (<90 mm Hg) was 13%, whereas it was more pronounced in the plain group (21% vs 6% in the hyperbaric group, P < 0.05), which required more ephedrine (P < 0.05) and in which a greater incidence of nausea was noticed (P < 0.05). We conclude that the use of a small dose of intrathecal bupivacaine combined with sufentanil plus our described preloading regimen resulted in a lower incidence of hypotension. Further, we conclude that the use of hyperbaric bupivacaine in this manner provides a more reliable block and a lower incidence of hypotension than plain bupivacaine. IMPLICATIONS: A small dose of hyperbaric bupivacaine 0.5% combined with sufentanil used intrathecally during cesarean section offered a more reliable cephalad spread of the spinal block than the glucose-free combination, which was reflected in a lower incidence of hypotension and nausea.

Hydroxyethylstarch compared with modified gelatin as volume preload before spinal anaesthesia for Caesarean section.

We studied 90 patients undergoing elective Caesarean section under spinal anaesthesia who received lactated Ringer's solution 1000 ml with up to 1000 ml of modified gelatin, lactated Ringer's solution 1000 ml with up to 1000 ml of 6% hydroxyethylstarch or only up to 1000 ml of 6% hydroxyethylstarch. Lumbar puncture was performed as soon as 500 ml of the colloid were infused. The incidence of hypotension, number of patients requiring a vasopressor and doses of ephedrine required to restore arterial pressure were significantly lower in favour of those receiving the crystalloid-hydroxyethylstarch combination. In both groups receiving the 2000 ml preload, packed cell volume (PCV) values decreased by more than 20%, which may be of concern in patients already presenting with mild anaemia. In patients who received the colloid without the crystalloid, PCV values decreased by 14% but the risk of severe hypotension was comparable with the crystalloid-gelatin combination.

Epidural sufentanil for postoperative patient-controlled analgesia (PCA) with or without background infusion: a double-blind comparison.

To evaluate the usefulness of a concurrent infusion in patient-controlled epidural analgesia (PCEA), 40 patients scheduled for elective cesarean section under a combined spinal-epidural technique were assigned randomly in a double-blind fashion to receive sufentanil by PCEA with a concomitant infusion of either sufentanil or saline. The sufentanil 24-h consumption was significantly (P < 0.001) higher in those patients receiving the opioid-containing infusion (212.7 +/- 9.5 vs 128.4 +/- 10.8 micrograms, SEM). The number of additional demands and the quality of sleep did not differ between the two groups. The degree of sedation was significantly less pronounced in patients treated with incremental sufentanil doses only. The visual analog scale (VAS) pain scores at rest were identical in both groups except at 6 h (2.5 +/- 0.4 vs 3.7 +/- 0.3, in favor of the patients treated with the sufentanil background infusion). We conclude that, except for a lower pain score during the initial hours, a background infusion in PCEA with sufentanil does not offer major advantages in terms of sleep quality or sufentanil consumption. Side effects may be more pronounced owing to increased drug administration.