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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.

Frequency of hypotension and bradycardia during general anesthesia, epidural anesthesia, or integrated epidural-general anesthesia for total hip replacement

STUDY OBJECTIVE To evaluate the frequency of hypotension and bradycardia during integrated epidural-general anesthesia as compared with general anesthesia or epidural anesthesia alone. DESIGN Prospective, randomized, open, multicenter study. SETTING Inpatient anesthesia at 7 University or Hospital Departments of anesthesia. PATIENTS 210 ASA physical status I, II, and III patients undergoing elective total hip replacement. INTERVENTIONS Using a balanced randomization method, each hospital enrolled 30 consecutive patients who received integrated epidural-general anesthesia, epidural anesthesia, or general anesthesia. MEASUREMENTS AND MAIN RESULTS Occurrence of clinically relevant hypotension (systolic arterial blood pressure (BP) decrease >30% from baseline), or bradycardia (heart rate (HR) <45 bpm) requiring pharmacologic treatment were recorded, as well as routine cardiovascular parameters. Clinically relevant hypotension during induction of nerve block was reported in 13 patients receiving epidural block (18%) and 16 patients receiving epidural-general anesthesia (22%) (p = 0.67). Subsequently, 22 of the remaining 54 patients in the epidural-general anesthesia group (41%) developed hypotension after the induction of general anesthesia, as compared with 16 patients of the general anesthesia group (23%) (p = 0.049). No differences in HR or in frequency of bradycardia were observed in the three groups. CONCLUSIONS The induction of general anesthesia in patients with an epidural block up to T10 increased the odds of developing clinically relevant hypotension as compared with those patients who received no epidural block, and was associated with a twofold increase of the odds of hypotension as compared with the use of epidural anesthesia alone.

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

Background: 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.

Minimum Analgesic Dose of Epidural Sufentanil for First-stage Labor Analgesia: A Comparison between Spontaneous and Prostaglandin-induced Labors in Nulliparous Women

Background The aim of this prospective, double-blind, sequential allocation study was to compare the effects of spontaneous and prostaglandin-induced labor on the minimum analgesic dose of epidural sufentanil in the first stage of labor. Methods Seventy healthy, nulliparous women, at more than 37 weeks’ gestation with cervical dilatation from 2 to 4 cm, requesting epidural pain relief in labor were enrolled. The subjects were assigned to two different groups according to whether labor was spontaneous or induced with dinoprostone 0.5 mg. Parturients received 10 ml of the study solution through a lumbar epidural catheter. The initial dose was sufentanil 25 &mgr;g, and subsequent doses were determined by the response of the previous patient in the same group using up–down sequential allocation. The analgesic effectiveness was assessed using 100-mm visual analog pain scores. The up–down sequences were analyzed using the method of independent paired reversals and probit regression. Results The minimum analgesic dose of sufentanil in spontaneous labor was 22.2 &mgr;g (95% CI: 19.6, 22.8) and 27.3 &mgr;g (95% CI: 23.8, 30.9) in induced labor. The minimum analgesic dose of sufentanil in induced labor was significantly greater (P = 0.0014) than that in spontaneous labor (95% CI difference: 2.9, 9.3) by a factor of 1.3 (95% CI: 1.1, 1.5). Conclusion Prostaglandin induction of labor produces a significantly greater analgesic requirement than does spontaneous labor.

Epidural fentanyl plus bupivacaine 0.125 per cent for labour: analgesic effects

Ninety-five healthy nulliparous women, ASA physical status I–II with an uncomplicated pregnancy and single fetus in vertex position were given lumbar epidural analgesia. Patients in Group A (n = 35) received bupivacaine 0.125 per cent with epinephrine 1800.000; Groups B (n = 30) and C (n = 30) received the same agents as Group A but with the addition to the initial dose of 50 or 100 µg of fentanyl respectively. All patients were evaluated for duration and quality of analgesia, duration of labour, method of delivery and total dose of bupivacaine used. The addition of either 50 or 100 µg of fentanyl resulted in longer duration of analgesia (93 ± 9 min and 106 ± 8 min respectively vs 55 ± 7) and reduced bupivacaine total doses (64 ± 0.03 and 55 ± 1.5 respectively vs 109.5 ± 1.3). Only the addition of 100 µg of fentanyl improved significantly the quality of analgesia (43.3 per cent of excellent scores vs 6.6 per cent in Group B and 5.7 per cent in Group A). Addition of fentanyl did not affect the duration of labour, the method of delivery and the neonatal neurobehaviour scores.RésuméQuatre-vingt-quinze femmes nullipares en bonne santé ASA classe I–II lors ďune grossesse non-compliquée ont reçu une analgésie épidurale lombaire. Les patientes du groupe A(n = 35) ont reçu de la bupivacaïne 0.125 pour cent avec épinéphrine 1:800,000: les patientes du groupe B (n = 30) et C (n = 30) ont reçu les mêmes médicaments que celles du groupe A mais avec ľaddition ďune dose initiale de 50 ou 100 µg de fentanyl respectivement. Les patientes furent évaluées pour la durée et la qualité de ľanalgésie, la durée du travail, la méthode ďaccouchement et la dose totale de bupivacaïne utilisée. Ľaddition de 50 et 100 µg de fentanyl a prolongé la durée de ľanalgésie (93 ± 9 minutes et 106 ± 8 minutes respectivement versus 55 ± 7) et a réduit les doses totales de bupivacaïne (64 ± 0.003 et 55 ± 1.5 respectivement versus 109.5 ± 1.3). Seule ľaddition de 100 µg de fentanyl a amélioré significativement la qualité de ľanalgésie (43.3 pour cent des scores excellents versus 6.6 pour cent dans le groupe B et 5.7 pour cent dans le groupe A). Ľaddition de fentanyl n’a pas affecté la durée du travail, et la méthode de ľaccouchement et le score néonatal.

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.

Alkalinization improves the quality of lidocaine-fentanyl epidural anaesthesia for caesarean section

This double-blind randomized study of 116 healthy women was undertaken to evaluate whether alkalinization potentiated the analgesic effects of epidural fentanyl-lidocaine for elective Caesarean section. After a test-dose of 3 ml, lidocaine 2% with adrenaline 1:200,000, all patients received 100 μg, fentanyl in 5 ml saline and they were then divided into two groups, to receive incremental doses of 5 ml lidocaine 2% with adrenaline 1:200,000 with or without 0.1 mEq · ml−1 sodium bicarbonate, to obtain anaesthesia to T4. The addition of bicarbonate to lidocaine resulted in a mean (SD)pH increase from 6.58 (0.01) to 7.14 (0.02) and in a mean PCO2 increase from 3.8 (0.8) to 345.1 (5.9) mmHg. Onset of sensory analgesia to the S1 segment as well as the interval between the block and the delivery of the baby were shorter in the bicarbonate group (respectively 15.4 (6.9) vs 18.9 (4.8) min and 28.9 (9.5) versus 33.9 (11.8) min; P < 0.01 and 0.05). No differences were noted in the onset to T4 or in the degree of motor block. The percentage of patients experiencing pain during surgery and requiring intravenous analgesics was higher in the group which did not receive bicarbonate (3% vs 16%; P < 0.05). There were no differences in intraoperative maternal side-effects, neonatal outcome or in maternal venous and umbilical venous and arterial lidocaine concentrations between the groups. The concentrations of fentanyl in maternal plasma, umbilical artery, and the umbilical artery to maternal vein ratio were greater in the alkalinized group (P < 0.001). In conclusion, alkalinization improves the quality and reliability of epidural anaesthesia provided with fentanyl and lidocaine for Caesarean section in healthy mothers.RésuméCette étude randomisée à double inconnue est réalisée chez 116 patientes en bonne santé pour évaluer si l’alcalinisation potentialise les effets analgésiques de l’association fentanyllidocaïne en épidurale pour la césarienne programmée. Après une dose-test de lidocaïne 2% adrénalinée à 1:200,000 3 ml, toutes les patientes reçoivent fentanyl 100 μg dans du soluté physioloque et sont divisées en deux groupe. Elles reçoivent des doses progressives de lidocaine 2% adrénalinée à 1:200,000 5 ml avec ou sans bicarbonate de sodium 0,1 mEq · ml−1 jusquà ce que le niveau T4 soil atteint. L’addition de bicarbonate à la lidocaïne augmente en moyenne (±SD) le pH de 6,58 (0,01) à 7,14 (0,02) et la PCO2 en moyenne de 3,8 (0,8) à 345,1 (5,9) mmHg. Le debut de l’anesthésie sensorielle mesurée au niveau S1 et l’intervalle entre l’initiation du bloc et la naissance sont plus courts pour le groupe bicarbonate (respectivement 15,4 (6,9) min vs 18,9 (4,8) min et 28,9 (9,5) vs 33,9 (II,8) min; P < 0,01 et 0,05). On ne note pas de difference quant au début de l’analgésie à T4 ou au degré du bloc moteur. Le pourcentage de patientes qui ressentent de la douleur pendant la chirurgie et qui reçoivent un analgésique iv est plus élevé dans le groupe qui ne reçoit pas de bicarbonate (3% vs 16%; P < 0,05). On ne trouve pas de différence entre groupes pour l’incidence des effets secondaires, le pronostic néo-natal ou les concentrations plasmatiques ombilicales artérielles et veineuses. La concentration plasmatique de fentanyl dans l’artèreombilicale est plus élevée dans le groupe bicarbonate ainsi que le rapport veineux ombilical-artère matemelle (P < 0,001). En conclusion, l’alcalinisation améliore la qualité et la fiabilité de l’anesthésie épidurale produite par le fentanyl et la lidocaïne pour la césarienne de patientes en bonne santé.

Comparison of fentanyl with clonidine as adjuvants for epidural analgesia with 0.125% bupivacaine in the first stage of labor. A preliminary report

48 primiparae received epidural analgesia in labor with 10 ml of 0.125% bupivacaine with epinephrine 1:800 000, and then were divided in 4 equal groups (n = 12) to receive one of the following: 5 ml saline (B); 100 mug of fentanyl (BF); 150 microg of clonidine (BC); 75 microg of clonidine and 50 microg of fentanyl (BCF). All the patients had satisfactory analgesia. Onset was similar in the 4 groups but the duration of analgesia was significantly prolonged by the addition of either 100 microg of fentanyl or 150 microg of clonidine (respectively 89.8 min and 92.5 min vs 62.5 min) (P < 0.0001). The addition of both clonidine (75 microg) and fentanyl (50 microg) produced a considerably prolonged analgesia (177.5 min) (P < 0.0001). No episodes of bradycardia were observed. Hypotension, reversed by i.v. ephedrine, occurred in 2 patients of BCF group and in 1 patient of BF and BC groups. Only patients receiving fentanyl had pruritus. Both fentanyl and clonidine produced sedation, but both incidence and severity were greater with the mixture. No differences in neonatal outcome assessed by Apgar scores and NACS, were observed.

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.