Comparison of the effects of intrathecal ropivacaine, levobupivacaine, and bupivacaine for Caesarean section.

BACKGROUND: This study aimed to detect if intrathecal (i.t.) ropivacaine and levobupivacaine provided anaesthesia (satisfactory analgesia and muscular relaxation) and postoperative analgesia of similar quality to bupivacaine in patients undergoing Caesarean section. METHODS: Ninety parturients were enrolled. A combined spinal-epidural technique was used. Patients were randomly assigned to receive one of the following isobaric i.t. solutions: bupivacaine 8 mg (n=30), levobupivacaine 8 mg (n=30), or ropivacaine 12 mg (n=30), all combined with sufentanil 2.5 microg. An i.t. solution was considered effective if an upper sensory level to pinprick of T4 or above was achieved and if intraoperative epidural supplementation was not required. Sensory changes and motor changes were recorded. RESULTS: Anaesthesia was effective in 97, 80, and 87% of patients in the bupivacaine 8 mg, levobupivacaine 8 mg, and ropivacaine 12 mg groups, respectively. Bupivacaine 8 mg was associated with a significantly superior success rate to that observed in the levobupivacaine group (P<0.05). It also provided a longer duration of analgesia and motor block (P<0.05 vs levobupivacaine and ropivacaine). CONCLUSIONS: The racemic mixture of bupivacaine combined with sufentanil remains an appropriate choice when performing Caesarean sections under spinal anaesthesia.

The comparative toxicity of ropivacaine and bupivacaine at equipotent doses in rats.

We compared the toxicity of systemic local anesthetics bupivacaine and ropivacaine administered at equivalent and equipotent doses. In the first experiments, 18 male Wistar rats were anesthetized with thiopental and maintained under positive controlled ventilation. Electrocardiogram, electroencephalogram, and invasive arterial blood pressure were continuously recorded. The animals were randomly assigned to receive 3 mg x kg(-1) x min(-1) bupivacaine, 3 mg x kg(-1) x min(-1) ropivacaine IV (equivalent group), or 4.5 mg x kg(-1) x min(-1) ropivacaine (equipotent group). The timing of the occurrence of local anesthetic-induced toxic events (defined as the first QRS modification, dysrhythmia, seizures, moderate and severe bradycardia and hypotension, final systole) was recorded and the dose calculated. Eighteen additional rats, treated according to the same protocol were killed at the time of moderate, severe, and final hypotension for blood sampling and plasma bupivacaine and ropivacaine concentration measurement. In a third experiment, 15 awake rats (5 per group) received IV bupivacaine or ropivacaine (same infusion as in the first experiments) until seizure. At this moment, rats were allowed to recover from local anesthetic intoxication. In the first experiment, except for the first QRS modification, all the other toxic manifestations occurred at significantly larger doses (P<0.05) in the two ropivacaine groups in comparison to the bupivacaine group. In awake rats, all the animals intoxicated by ropivacaine easily recovered. In the bupivacaine group, two animals required cardiopulmonary resuscitation before any seizure activity could be detected, and only three rats survived. We conclude that, in the model used, ropivacaine, even at an equipotent dose, is less toxic than bupivacaine.

Ornipressin (Por 8): An efficient alternative to counteract hypotension during combined general/epidural anesthesia.

UNLABELLED: We sought to evaluate the efficacy and side effect profile of a small dose of ornipressin, a vasopressin agonist specific for the V1 receptor, administered to reverse the hypotension associated with combined general/epidural anesthesia. A total of 60 patients undergoing intestinal surgery were studied. After the induction of anesthesia, 7-8 mL of bupivacaine 0.5% with 2 microg/kg clonidine and 0.05 microg/kg sufentanil after an infusion of 5 mL of bupivacaine 0.06% with 0.5 microg x kg(-1) x h(-1) clonidine and 0.1 microg/h of sufentanil were administered by an epidural catheter placed at T7-8 vertebral interspace. When 20% reduction of baseline arterial blood pressure developed, patients were randomly assigned to receive, in a double-blinded design, dopamine started at 2 microg x kg(-1) x min(-1), norepinephrine started at 0.04 microg x kg(-1) x min(-1), or ornipressin started at 1 IU/h. Fifteen patients presenting without hypotension were used as control subjects. Beside routine monitoring, S-T segment analysis, arterial lactacidemia, and gastric tonometry were performed. Ornipressin restored arterial blood pressure after 8 +/- 2 vs 7 +/- 3 min in the norepinephrine group and 11 +/- 3 min in the dopamine group (P < 0.05). This effect was achieved with 2 IU/h of ornipressin in most of the patients (11 of 15). Ornipressin did not induce any modification of the S-T segment; however, it significantly increased intracellular gastric PCO(2) (P < 0.05), indicating splanchnic vasoconstriction. IMPLICATIONS: In the population studied, small-dose ornipressin was effective to restore arterial blood pressure without causing major ischemic side effects.