Sebastiani M

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.

Which induction drug for cesarean section? a comparison of thiopental sodium, propofol, and midazolam

STUDY OBJECTIVE To determine maternal and neonatal effects of three different induction drugs (thiopental sodium, propofol, and midazolam) for cesarean section. DESIGN Randomized, double-blind study. SETTING Inpatient obstetric department at a general hospital. PATIENTS 90 healthy patients undergoing elective cesarean section with general anesthesia. INTERVENTIONS 3 groups of 30 patients each receiving thiopental 5 mg/kg, propofol 2.4 mg/kg, or midazolam 0.3 mg/kg for induction of anesthesia. MEASUREMENTS AND MAIN RESULTS Time to induce anesthesia, hemodynamic changes, depth of anesthesia, recovery after anesthesia, placental transfer, and neonatal outcome (Apgar and neurobehavioral examinations) were studied. In the thiopental and midazolam groups, systolic blood pressure and heart rate rose following endotracheal intubation and skin incision (p < 0.001 and p < 0.0025, respectively), while in the propofol group, there was significant hypotension after induction (p < 0.005). Electroencephalographic patterns showed a light depth of anesthesia with propofol and midazolam between anesthesia induction and delivery, confirmed by the presence of clinical signs of light anesthesia in 50% of propofol patients and 43% of midazolam patients. Time to induce anesthesia was longer with midazolam (p < 0.0001). Neonates in the midazolam and propofol groups had lower Apgar and neurobehavioral scores than those in the thiopental group. Umbilical artery to umbilical vein ratios were above 1 in the propofol and midazolam groups. CONCLUSION Thiopental still remains the first-choice induction drug for cesarean section. The slow induction time with midazolam may put the mother at risk for pulmonary inhalation. A plane of anesthesia that may risk awareness and potential neonatal depression is the main drawback of the two newer induction drugs.

Propofol and thiopentone for caesarean section revisited: maternal effects and neonatal outcome

In 56 women undergoing elective caesarean section, general anaesthesia was induced with either propofol 1% or thiopentone 2.5% followed by 50% nitrous oxide in oxygen and isoflurane 0.75% until delivery. In the thiopentone group the arterial pressure rose following tracheal intubation and skin incision, while in the propofol group there was a significant tendency to hypotension immediately following induction of anaesthesia. There were differences in electroencephalogram (EEG) between the groups, while laryngoscopy, intubation and surgical stimulation had no effect on EEG pattern. Recovery after anaesthesia did not differ between groups. None of the patients had recall of the intraoperative period, but 53% of patients induced with propofol showed signs of light anaesthesia between induction and delivery. Neonates in the propofol group had lower Apgar scores 1 min after birth than those in the thiopentone group, but these differences were no longer significant at 5 min. No differences were noted in neurobehavioural status at 1, 4 and 24 h.

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

Background: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. Methods: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. Results: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. Conclusions: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.

Epidural mepivacaine for cesarean section: Effects of a pH-adjusted solution

STUDY OBJECTIVE To determine the clinical effects of the alkalinization of 2% mepivacaine with epinephrine used for epidural block during cesarean section. DESIGN Randomized, double-blind, placebo-controlled (standard commercial preparation of 2% mepivacaine with epinephrine) study. SETTING Inpatient obstetric department at a general hospital. PATIENTS Seventy patients scheduled for elective cesarean section under epidural anesthesia. INTERVENTIONS Two groups of 35 patients each receiving either the standard commercial preparation of mepivacaine or the pH-adjusted solution (prepared with the addition of 0.1 meq/ml of sodium bicarbonate to the standard commercial solution). MEASUREMENTS AND MAIN RESULTS Measurements of sensory (pinprick) and motor (Bromages criteria) block were taken at 1- to 2-minute intervals beginning after the completion of the epidural injection. Increasing the pH of the mepivacaine resulted in a significant shortening of the time of analgesia onset (9.3 minutes compared with 16.01 minutes, p less than 0.01) and of peak effect (11.1 minutes compared with 21.2 minutes, p less than 0.01). The alkalinization did not affect duration of the block, intensity of motor block, or mean dose of local anesthetic used. CONCLUSION The alkalinization allowed the surgery to proceed more rapidly, significantly decreasing the time interval between epidural block and delivery of the infant.