Ph. E. Gautier

Intrathecal ropivacaine for ambulatory surgery - A comparison between intrathecal bupivacaine and intrathecal ropivacaine for knee arthroscopy

Background The rationale of this study was to evaluate intrathecal ropivacaine for ambulatory surgery. Methods: One hundred fifty patients with American Society of Anesthesiologists physical status 1 scheduled for knee arthroscopy were studied. Patients were randomly assigned to receive 4 ml of one of five isobaric intrathecal solutions: Patients in group 1 (n = 30) received 8 mg of bupivacaine; patients in group 2 (n = 30) received 8 mg ropivacaine; patients in group 3 (n = 30) received 10 mg ropivacaine; patients in group 4 (n = 30) received 12 mg ropivacaine; and patients in group 5 (n = 30) received 14 mg ropivacaine. The level and duration of sensory anesthesia were recorded along with the intensity and duration of motor block. Patients were interviewed to identify transient neurologic symptoms. Results: Intrathecal ropivacaine 10 mg produced shorter sensory anesthesia and motor blockade than bupivacaine 8 mg (152 +/- 44 min and 135 +/- 41 min vs. 181 +/- 44 min and 169 +/- 52 min, mean +/- SD; P < 0.05). However, the quality of intraoperative analgesia was significantly lower in the 10-mg ropivacaine group (P < 0.05). Ropivacaine 12 mg produced sensory and motor block almost comparable to bupivacaine 8 mg. Ropivacaine 14 mg produced sensory and motor block comparable to ropivacaine 12 mg but significantly increased the time to void. No sign of transient radicular irritation mere noted. Conclusion: Intrathecal ropivacaine 12 mg is approximately equivalent to bupivacaine 8 mg. At this dose, ropivacaine offers no significant advantage compared with bupivacaine.

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 · kg−1 · min−1 bupivacaine, 3 mg · kg−1 · min−1 ropivacaine IV (equivalent group), or 4.5 mg · kg−1 · 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. Implications Our results clearly demonstrate that ropivacaine, even used at an equipotent dose, has a wider therapeutic index than bupivacaine.

Intrathecal clonidine combined with sufentanil for labor analgesia

Background Intrathecal sufentanil provides rapid‐onset and complete analgesia for the first stage of labor. The dose required to produce this effect can be associated with maternal respiratory depression, hypotension, nausea, or pruritus. Because clonidine potentiates the analgesic effects of opioids without increasing their side effects, the authors wanted to determine the efficacy of low doses of intrathecal clonidine (15 and 30 micro gram) combined with sufentanil. Methods Ninety‐eight parturient requesting labor analgesia were studied. In a combined spinal‐epidural technique, patients were randomly assigned to receive one of the following intrathecal solutions: either 15 micro gram clonidine (n = 10); 30 micro gram clonidine (n = 10); 2.5 micro gram sufentanil (n = 13); 5 micro gram sufentanil (n = 13); 2.5 micro gram sufentanil and 15 micro gram clonidine (n = 13); 2.5 micro gram sufentanil and 30 micro gram clonidine (n = 13); 5 micro gram sufentanil and 15 micro gram clonidine (n = 13); or 5 micro gram sufentanil and 30 micro gram clonidine (n = 13). Visual analog scores for pain, blood pressure, heart rate, sensory levels, incidence of nausea and pruritus, and motor blockade, and maternal and cord blood concentrations of clonidine were recorded. Results Patients receiving 30 micro gram intrathecal clonidine with 2.5 or 5 micro gram intrathecal sufentanil had significantly longer‐lasting analgesia (145 +/‐ 36 and 145 +/‐ 43 min vs. 104 +/‐ 35 for those receiving 5 micro gram intrathecal sufentanil alone). Clonidine levels were undetectable in maternal serum. Conclusions Thirty micrograms of intrathecal clonidine combined with 2.5 or 5 micro gram intrathecal sufentanil significantly increased the duration of analgesia during the first stage of labor without adverse maternal or fetal effects.