Adding sufentanil to levobupivacaine or ropivacaine intrathecal anaesthesia affects the minimum local anaesthetic dose required.

We carried out this prospective, randomized, double-blind study in order to evaluate whether the intrathecal addition of sufentanil 3.3 mcg affects both the minimum local anaesthetic dose (MLAD) of spinal levobupivacaine and ropivacaine for a caesarean section and enhances the spinal block characteristics.One hundred and eighty women were randomly allocated into four groups: levobupivacaine (Group L), levobupivacaine plus sufentanil (Group L+S), ropivacaine (Group R) and ropivacaine plus sufentanil (Group R+S). Each received 3 ml of the study solution intrathecally as part of a combined spinal/epidural technique. The initial dose was 12 mg for Groups L and L+S, and 15 mg for Groups R and R+S. The test solution was required to achieve a visual analogue pain score (VAPS) of 30 mm or less to be considered effective at skin incision, uterine incision, birth, peritoneal closure and at the conclusion of surgery. Effective or ineffective responses determined a 0.5 mg decrease or increase of the same drug, respectively, for the next patient in the same group, using an up-down sequential allocation.Using the Dixon and Massey formula, the MLAD was 10.65 mg [confidence interval (CI) 95\%: 10.14-11.56] in Group L, 4.73 mg (CI 95\%: 4.39-5.07) in Group L+S, 14.12 mg (CI 95\%: 13.50-14.60) in Group R and 6.44 mg (CI 95\%: 5.86-7.02) in Group R+S.The addition of sufentanil reduced the MLAD of both the local anaesthetics. It did not affect their potency ratio significantly and resulted in enhanced spinal anaesthesia

Minimum local analgesic dose: effect of different volumes of intrathecal levobupivacaine in early labor.

This double-blind, randomized study was aimed at detecting the effect of three different volumes of intrathecal levobupivacaine on the minimum local analgesic dose in early labor.Ninety-three nulliparous women requesting combined spinal-epidural analgesia, at more than 37 weeks gestation, with spontaneous onset of labor, cervical dilatation from 2 to 5 cm, were enrolled. Parturients received 10 ml (group 10), 5 ml (group 5), or 2.5 ml (group 2.5) of the spinal solution containing plain levobupivacaine diluted with 0.9\% wt/vol saline to achieve the desired dose and volume at room temperature. A lumbar epidural catheter was then placed. The initial dose for each group was 2.0 mg, and the following doses were determined by the response of the previous patient using up-down sequential allocation. The authors required the test solution to achieve a visual analog pain score of 10 mm or less to be considered effective. The up-down sequences were analyzed using the Dixon and Massey formula and regression logistic model.The minimum local analgesic dose of spinal levobupivacaine in spontaneously laboring women was 1.35 mg (95\% confidence interval, 1.25-1.45 mg) in group 10, 1.63 mg (95\% confidence interval, 1.51-1.76 mg) in group 5, and 1.97 mg (95\% confidence interval, 1.89-2.05 mg) in group 2.5. A unit change in volume increased the odds of an effective response multiplicatively by a factor of 1.8.Analgesia can be achieved using lower doses and higher volumes even in subarachnoid space. The important role of the volume should be considered not only in epidural but also in spinal analgesia

Minimum local anaesthetic dose (MLAD) of intrathecal levobupivacaine and ropivacaine for Caesarean section.

We determined the minimum local anaesthetic dose (MLAD) of spinal levobupivacaine and ropivacaine for Caesarean section. Ninety women were randomly allocated to two groups and received 3 ml of study solution by a combined spinal/epidural technique. The initial dose was 12 mg for levobupivacaine and 17 mg for ropivacaine groups. To be considered effective, a test solution had to achieve a visual analogue pain score (VAPS) of 30 mm or less at skin incision, uterine incision, birth, peritoneal closure, and at the end of surgery. Effective or ineffective responses determined, respectively, a 0.3 mg decrease or increase of the same drug for the next patient in the same group, using up-down sequential allocation. The MLAD of levobupivacaine was 10.58 mg (CI 95\%: 10.08-11.09) and the MLAD of ropivacaine 14.22 mg (CI 95\%: 13.67-14.77), using the Dixon and Massey formula. The potency ratio between spinal levobupivacaine and spinal ropivacaine was 1.34

High volume of subarachnoid levobupivacaine decreases drug requirement in first stage labor analgesia.

Using the statistic method of sequential allocation, we realized a prospective double-blind study in order to establish the minimum local anesthetic concentration (MLAC) of large intrathecal volume of levobupivacaine, during the first stage labour analgesia in spontaneous and induced laboring women.Seventy-five nulliparous, at term, with cervical dilatation <5 cm parturients requesting combined spinal/epidural analgesia, were enrolled. The starting concentration was chosen according to recent literature. Total volume of study solution was 10 ml and efficacy was assessed with a visual analogue pain scale at the height of the uterine contraction.We established that MLAC of levobupivacaine, in 10 ml intrathecal volume, during the first stage of spontaneous and induced labour was 0.0134\% and 0.0195\%, respectively. No complications occurred during the study and the only side effect was shivering, which is common even in other anesthetic techniques. We produced a very selective sensitive block. Neither sympathetic nor motor block occurred.Low intrathecally concentration of local anesthetic allows the anesthetist to reduce the total amount of drug and improves not only the differential blockade between motor and sensitive but also between sympathetic and sensitive fibers