Hyperbaric spinal ropivacaine for cesarean delivery: a comparison to hyperbaric bupivacaine.

We evaluated the clinical efficacy and safety of spinal anesthesia with 0.5% hyperbaric ropivacaine compared with 0.5% hyperbaric bupivacaine for elective cesarean delivery. Sixty healthy, full-term parturients were randomly assigned to receive either 12 mg of 0.5% hyperbaric bupivacaine or 18 mg of 0.5% hyperbaric ropivacaine intrathecally. There were no significant differences in demographic or surgical variables or neonatal outcomes between groups. Onset time of sensory block to T10 or to peak level was later in the Ropivacaine group (P < 0.05). The median (range) peak level of analgesia was T3 (T1-5) in the Bupivacaine group and T3 (T1-4) in the Ropivacaine group. Time for sensory block to recede to T10 did not differ between groups. Duration of sensory block was shorter in the Ropivacaine group (188.5 +/- 28.2 min vs 162.5 +/- 20.2 min; P < 0.05). Complete motor block of the lower extremities was obtained in all patients. Ropivacaine also produced a shorter duration of motor blockade than bupivacaine (113.7 +/- 18.6 min vs 158.7 +/- 31.2 min; P < 0.000). The intraoperative quality of anesthesia was excellent and similar in both groups. Side effects did not differ between groups. Eighteen milligrams of 0.5% hyperbaric ropivacaine provided effective spinal anesthesia with shorter duration of sensory and motor block, compared with 12 mg of 0.5% hyperbaric bupivacaine when administered for cesarean delivery Implications: Eighteen milligrams of 0.5% hyperbaric ropivacaine provided effective spinal anesthesia with shorter duration of sensory and motor block, compared with 12mg of 0.5% hyperbaric bupivacaine when administered for cesarean delivery.     

Intrathecal anesthesia: ropivacaine versus bupivacaine

We compared intrathecal ropivacaine to bupivacaine in patients scheduled for transurethral resection of bladder or prostate. Doses of ropivacaine and bupivacaine were chosen according to a 3:2 ratio found to be equipotent in orthopedic surgery. One hundred patients were randomly assigned to blindly receive either 10 mg of isobaric bupivacaine (0.2%, n = 50) or 15 mg of isobaric ropivacaine (0.3%, n = 50) over 30 s through a 27-gauge Quincke needle at the L2-3 level in the sitting position. Onset and offset times for sensory and motor blockades and mean arterial blood pressure were recorded. Pain at surgical site requiring supplemental analgesics was recorded. Cephalad spread of sensory blocks was higher with bupivacaine (median level, cold T(4) and pinprick T(7)) than with ropivacaine (cold T(6) and pinprick T(9)) (P<0.001). Eight patients in Group Ropivacaine received IV alfentanil (P<0.01). Onset time (mean +/- SD) to T(10) anesthesia and offset time at L2 were not different (bupivacaine = 13 +/-8 min, 127+/-41 min; ropivacaine = 11+/-7 min, 105+/-29 min). Complete motor blockade occurred in 43 patients with bupivacaine and in 41 patients with ropivacaine (not significant). Total duration of motor blockade was not different. No difference in hemodynamic effects was detected between groups. No patient reported back pain. We conclude that 15 mg of intrathecal ropivacaine provided similar motor and hemodynamic effects but less potent anesthesia than 10 mg of bupivacaine for endoscopic urological surgery.     

Comparison of 0.5% ropivacaine and 0.5% bupivacaine for epidural anesthesia in patients undergoing lower-extremity surgery

Ropivacaine is an amide local anesthetic structurally related to, but appearing less cardiotoxic, than bupivacaine. The authors' investigation was designed in a randomized, double-blind fashion to compare the clinical effectiveness of ropivacaine and bupivacaine in patients undergoing lower-extremity surgery. Forty-five patients were randomized to receive 20 ml of 0.5% ropivacaine or bupivacaine. Intermittent sensory (pinprick) and motor (Bromage score) measurements were made while the block was in effect, and changes in heart rate, blood pressure and amounts of additional analgesics, sedatives and other medications were also recorded. Presence of tourniquet pain and the quality of anesthesia were also assessed. One patient was excluded from analysis; thus, 22 patients each received ropivacaine or bupivacaine. No differences were found in patient or perioperative characteristics between the groups. The quality and extent of sensory and motor blockade between groups were comparable, although bupivacaine was slightly longer acting. Cardiovascular changes, incidence of tourniquet pain, and the amounts of supplemental medications necessary were also similar between groups. The authors found 0.5% ropivacaine and bupivacaine to be clinically similar in both sensory- and motor-blocking characteristics, with the exception that bupivacaine produced a blockade of slightly longer duration. Because ropivacaine is reported to be less cardiotoxic than bupivacaine in animal studies, the similarity of clinical epidural anesthesia may make ropivacaine the preferred agent.     

A comparison of intrathecal plain solutions containing ropivacaine 20 or 15 mg versus bupivacaine 10 mg

Ropivacaine, which blocks sensory nerve fibers more readily than motor fibers, is considered to be less potent than bupivacaine. Our hypothesis was that, when used in spinal anesthesia for day surgery, ropivacaine 15 and 20 mg would provide faster motor recovery than bupivacaine 10 mg. This prospective, randomized, double-blinded study included 90 ambulatory lower-extremity surgery patients who received 2 mL of ropivacaine 1%, ropivacaine 0.75%, or bupivacaine 0.5%. Motor block was tested with the Bromage scale, and sensory block was tested with pinprick. Ropivacaine 15 mg provided faster recovery of motor block (150 min) than did bupivacaine 10 mg (210 min; P = 0.005), but the median duration of sensory block at T10 (140 min) did not differ significantly from that with bupivacaine 10 mg (140 min). The median duration of sensory block at T10 was significantly longer with ropivacaine 20 mg (170 min) than with bupivacaine 10 mg (140 min; P = 0.005), but the median recovery from motor block (210 min) did not differ significantly. We conclude that the duration of sensory block of ropivacaine was two thirds and the duration of motor block was half when compared with bupivacaine, with calculations based on the duration-per-milligram of the local anesthetic.     

Comparison of ropivacaine and bupivacaine for epidural analgesia during labor]

OBJECTIVES: To compare the analgesic efficacy and level of motor block using two local anesthetics, ropivacaine and bupivacaine, during labor. MATERIAL AND METHODS: Sixty nulliparous women were enrolled during labor after full-term pregnancies. They were randomly assigned to receive epidural analgesia with ropivacaine (group R) or bupivacaine (group B). Group R patients received 10 ml of 0.18% ropivacaine with 5 microgram/ml of fentanyl followed by continuous epidural infusion of 0.1% ropivacaine with 2 microgram/ml of fentanyl at a rate of 10 ml/h. Group B patients received 10 ml of 0.15% bupivacaine with 5 microgram/ml of fentanyl followed by continuous epidural perfusion of 0.0625% bupivacaine with 2 microgram/ml of fentanyl at the same rate. Pain intensity was assessed on a visual analog scale, motor blockade on a Bromage scale, and level of sensory block at different moments. We also recorded total doses of local anesthetic employed during continuous epidural infusion, manner of final delivery, Apgar score, degree of maternal satisfaction and side effects. RESULTS: The demographic and delivery characteristics were similar in both groups. We found no statistically significant differences between the two groups for level of motor blockade, which was nil for 29 patients (96.66%) in group R and 28 patients (93.33%) in group B. No differences in degree of pain or level of sensory block (T8-T10 in both groups) were observed.The total doses of local anesthetic used were similar at 23.7 +/- 11.6 mg in group R and 16.5 +/- 7.3 mg in group B (non-significant difference). Nor did we find differences in manner of delivery, neonatal Apgar scores, degree of maternal satisfaction or side effects. CONCLUSION: Ropivacaine and bupivacaine are equally effective for epidural analgesia during labor at the doses used and they do not cause a relevant level of motor blockade.     

Hyperbaric spinal ropivacaine: a comparison to bupivacaine in volunteers

BACKGROUND: Ropivacaine is a newly introduced local anesthetic that may be a useful alternative to low-dose bupivacaine for outpatient spinal anesthesia. However, its relative potency to bupivacaine and its dose-response characteristics are unknown. This double-blind, randomized, crossover study was designed to determine relative potencies of low-dose hyperbaric spinal ropivacaine and bupivacaine and to assess the suitability of spinal ropivacaine for outpatient anesthesia. METHODS: Eighteen healthy volunteers were randomized into three equal groups to receive one spinal administration with bupivacaine and a second with ropivacaine, of equal-milligram doses (4, 8, or 12 mg) of 0.25% drug with 5% dextrose. The duration of blockade was assessed with (1) pinprick, (2) transcutaneous electrical stimulation, (3) tolerance to high tourniquet, (4) electromyography and isometric force dynamometry, and (5) achievement of discharge criteria. Differences between ropivacaine and bupivacaine were assessed with linear and multiple regression. P < 0.05 was considered significant. RESULTS: Ropivacaine and bupivacaine provided dose-dependent prolongation of sensory and motor block and time until achievement of discharge criteria (R2 ranges from 0.33-0.99; P values from < 0.001 through 0.01). Spinal anesthesia with ropivacaine was significantly different from bupivacaine and was approximately half as potent for all criteria studied. A high incidence of back pain (28%; P = 0.098) was noted after intrathecal ropivacaine was given. CONCLUSION: Ropivacaine is half as potent and in equipotent doses has a similar profile to bupivacaine with a higher incidence of side effects. Low-dose hyperbaric spinal ropivacaine does not appear to offer an advantage over bupivacaine for use in outpatient anesthesia.     

Comparison of bupivacaine- and ropivacaine-induced conduction blockade in the isolated rabbit vagus nerve

Ropivacaine (LEA-103) is a new amino-amide local anesthetic agent the chemical structure and anesthetic properties of which are similar to bupivacaine. Preliminary studies in animals indicate that the CNS toxicities of ropivacaine and bupivacaine are similar, but that ropivacaine may have less arrhythmogenic effects than bupivacaine. The current study arrhythmogenic effects than bupivacaine. The current study was designed to compare the in vitro potency, onset and recovery from block of ropivacaine and bupivacaine using an isolated rabbit vagus nerve model. The effect of varying concentrations of ropivacaine and bupivacaine on the compound action potential of A and C nerve fibers was assessed to determine whether motor and sensory fibers have different sensitivities to the two agents. The results showed that the depressant effect of bupivacaine was 16% greater than that of ropivacaine on motor fibers, but only 3% greater on sensory fibers. An analysis of variance indicated that this was a statistically significant difference (P = 0.028). Thus, at the concentrations tested, ropivacaine appears to produce relatively less blockade of motor fibers than does bupivacaine but with similar sensory blockade. The onset of this difference became significant as early as five minutes after the drug exposure was begun. No significant differences in recovery times were observed.     

Comparative motor-blocking effects of bupivacaine and ropivacaine, a new amino amide local anesthetic, in the rat and dog

Ropivacaine (S-(-)-1-propyl-2',6'-pipecoloxylidide) is a new local anesthetic that is structurally related to mepivacaine and bupivacaine. The comparative effects of ropivacaine and bupivacaine on motor function were assessed in the laboratory rat and dog. (It was not possible to accurately evaluate sensory blockade in these models.) Several concentrations of both agents were injected in the region of the sciatic nerve of the rat and into the lumbar epidural or subarachoid space in the dog. Epidural blockade was also performed utilizing solutions of ropivacaine and bupivacaine which contained epinephrine (1:200,000). The rat sciatic block studies indicate that at concentrations of 0.5 and 0.75%, ropivacaine had a slightly shorter time of onset and duration of motor blockade than did bupivacaine. In the epidural and spinal studies in the dog, ropivacaine was less potent and had a shorter duration of motor blockade than did bupivacaine at equal drug concentrations. A 1.0% solution of ropivacaine produced epidural motor blockade similar in onset and duration to that achieved with a 0.75% solution of bupivacaine. Epinephrine did not significantly prolong the duration of motor blockade of either agent after epidural administration.     

Intrathecal ropivacaine for ambulatory surgery.

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 8mg (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 were noted. CONCLUSION: Intrathecal ropivacaine 12 mg is approximately equivalent to bupivacaine 8 mg. At this dose, ropivacaine offers no significant advantage compared with bupivacaine.     

0.75% and 0.5% ropivacaine for axillary brachial plexus block: a clinical comparison with 0.5% bupivacaine

BACKGROUND AND OBJECTIVES: Although ropivacaine has been extensively studied for epidural anesthesia, very few reports exist on brachial plexus block. We therefore decided to investigate the clinical features of axillary brachial plexus anesthesia with two different concentrations of ropivacaine (0.5% and 0.75%) and to compare the results with those obtained with 0.5% bupivacaine. METHODS: Three groups of patients were randomized and prospectively studied. They received, in a double-blind fashion, 32 mL of the local anesthetic solution into the midaxilla, by a nerve-stimulator technique. Onset time in each of the stimulated nerves was recorded both for the sensory and motor block. Peak time (ready to surgery), rate of supplemental blocks, need for intraoperative opioids, duration of sensory and motor block, postoperative analgesic requirements, and patient satisfaction were also recorded. RESULTS: The rate of complete sensory and motor block observed with both ropivacaine groups was higher at 10, 15, and 20 minutes postinjection (P < .001). The mean peak time was shorter with ropivacaine than with bupivacaine (R50 = 16.37 minutes, R75 = 14.7 minutes, B = 22.3 minutes, P < .05). The quality of the anesthesia was higher with ropivacaine, as measured by the intraoperative needs for opioids and the overall patient's satisfaction (P < .05). No significant differences were noted with all the other studied parameters. CONCLUSION: Ropivacaine showed advantages over bupivacaine for axillary brachial plexus block. Because no statistical differences were found between the two ropivacaine groups, we therefore conclude that 0.75% does not add benefit and that 0.5% ropivacaine should be used to perform axillary brachial plexus blocks.     

Ropivacaine

This paper describes the pharmacological, pharmacokinetic and pharmacodynamic features of ropivacaine on both an experimental and clinical level. Ropivacaine is an amide-type local anesthetic whose chemical structure is related to that of mepivacaine and bupivacaine and whose duration of effect falls between the two. Ropivacaine is a less potent effector of motor blockade than bupivacaine, and its toxic effects on the central nervous system and myocardial tissue is likewise less. Ropivacaine has been employed for epidural anesthesia and analgesia (including through a caudal approach), for peripheral motor blockade, for local infiltration (in gel form), and for intravenous regional anesthesia in ophthalmologic surgery involving peri- and retrobulbar blockade. Subarachnoid use has not yet been accepted in Spain, although phase IV clinical trials of this application have begun. Concentrations of 2 mg/ml (0.2%) and 7.5 mg/ml (0.75%) and 10 mg/ml (1%) are available in Spain.     

Comparative Systemic Toxicity of Ropivacaine and Bupivacaine in Nonpregnant and Pregnant Ewes

Background: Ropivacaine is a new amide local anesthetic, having therapeutic properties similar to those of bupivacaine but with a wider margin of safety. Bupivacaine is probably the most commonly used drug in obstetric epidural analgesia, even though laboratory studies have suggested that pregnancy increases the cardiotoxicity of bupivacaine but not of other local anesthetics. The current study was designed to reevaluate, in a random and blinded fashion, the systemic toxicity of bupivacaine and ropivacaine in nonpregnant and pregnant sheep.

Methods: Chronically prepared nonpregnant and pregnant ewes were randomized to receive an intravenous infusion of ropivacaine or bupivacaine at a constant rate of 0.5 mg *symbol* kg sup -1 *symbol* min sup -1 until circulatory collapse. The investigators were blinded to the identity of local anesthetic. Heart rate, arterial blood pressure, and cardiac rhythm were monitored throughout the study. Arterial blood samples were obtained before infusion and at the onset of toxic manifestations, which appeared in the following sequence: convulsions, hypotension, apnea, and circulatory collapse. Serum drug concentrations and protein binding were determined. Blood pH and gas tensions were measured.

Results: There were no significant differences between nonpregnant and pregnant animals in the doses or serum concentrations of either drug required to elicit toxic manifestations. In nonpregnant animals, similar doses and serum concentrations of ropivacaine and bupivacaine were associated with the onset of convulsions and circulatory collapse. In pregnant ewes, greater doses of ropivacaine as compared to bupivacaine were required to produce convulsions (7.5 plus/minus 0.5 vs. 5.0 plus/minus 0.6 mg *symbol* kg sup -1) and circulatory collapse (12.9 plus/minus 0.8 vs. 8.5 plus/minus 1.2 mg *symbol* kg sup -1). The corresponding serum concentrations of ropivacaine were similar to those of bupivacaine. Pregnancy did not affect the serum protein binding of either drug. The proportion of animals manifesting a malignant ventricular arrhythmia as the terminal event was similar among all groups.     

Caudal block in children: ropivacaine compared with bupivacaine.

BACKGROUND: Bupivacaine provides reliable, long-lasting anesthesia and analgesia when given via the caudal route. Ropivacaine is a newer, long-acting local anesthetic that (at a concentration providing similar pain relief) has less motor nerve blockade and may have less cardiotoxicity than bupivacaine. METHODS: In a double-blind trial, 81 healthy children, undergoing ambulatory surgical procedures, were randomly allocated to receive caudal analgesia with either bupivacaine or ropivacaine, 0.25%, 1 mVkg. All blocks were placed by an attending anesthesiologist or an anesthesia fellow after induction of general anesthesia. RESULTS: Data were available for 75 children. There were no significant differences between the two groups in baseline characteristics or in anesthesia, surgery, recovery room, or day surgery unit durations. The quality and duration of postoperative pain relief did not differ. Motor and sensory effects were similar. Time to first micturition did not differ. CONCLUSION: Ropivacaine (0.25%, 1 ml/kg) provided adequate postoperative analgesia with no difference from bupivacaine (0.25%, 1 ml/kg) in quality and duration of pain relief, motor and sensory effects, or time to first micturition in our study children.     

Spinal ropivacaine or bupivacaine for cesarean delivery: a prospective, randomized, double-blind comparison

BACKGROUND AND OBJECTIVES: The aim of this prospective, randomized, double-blinded study was to compare clinical efficacy and safety of ropivacaine and bupivacaine given intrathecally in combination with morphine for cesarean delivery. METHODS: With ethical committee approval and a written informed consent, 60 women scheduled for elective cesarean delivery under spinal anesthesia were randomly allocated to receive spinal anesthesia with either 20 mg ropivacaine plus 0.1 mg morphine (n = 30) or 15 mg bupivacaine plus 0.1 mg morphine (n = 30). Profile of spinal block (onset and recovery times), cardiovascular effects, and quality of postoperative analgesia (patient-controlled morphine) were recorded by a blinded observer. RESULTS: The onset time of motor block was shorter after bupivacaine (8 +/- 2 min) than after ropivacaine (12 +/- 5 minutes) (P <.05), whereas duration of both sensory and motor blocks was longer after bupivacaine (139 +/- 37 minutes and 254 +/- 76 minutes) than after ropivacaine (112 +/- 27 minutes and 211 +/- 48 minutes) (P <.01 and P <.05, respectively). No differences in intraoperative quality of anesthesia and clinical hypotension requiring ephedrine administration were observed between the two groups. Postoperative analgesia was similarly effective in both groups; however median consumption of patient-controlled morphine during the first 24 hours after surgery was higher in patients of group Ropivacaine (5 mg; range, 0 to 18 mg) than in patients of group Bupivacaine (2 mg; range, 0 to 7 mg) (P <.01). CONCLUSION: Spinal anesthesia produced with 20 mg ropivacaine plus 0.1 mg morphine is as effective and safe as that provided by 15 mg bupivacaine plus 0.1 mg morphine, with an earlier recovery of sensory and motor functions after surgery.     

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 8mg (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 were noted.     

Intrathecal ropivacaine and clonidine for ambulatory knee arthroscopy: a dose-response study

BACKGROUND: The aim of this study was to evaluate the association of a small dose of intrathecal ropivacaine with small doses of intrathecal clonidine for ambulatory surgery. METHODS: One hundred twenty patients, classified as American Society of Anesthesiologists physical status I and scheduled for knee arthroscopy, were studied. Patients were randomly assigned to receive 4 ml of one of the following double-blinded isobaric intrathecal solutions: 8 mg of ropivacaine (group 1; n =30); 8 mg ropivacaine plus 15 microg clonidine (group 2; n =30); 8 mg ropivacaine plus 45 microg clonidine (group 3; n =30); and 8 mg ropivacaine plus 75 microg clonidine (group 4; n =30). The level and duration of sensory anesthesia were recorded, along with the intensity and duration of motor block. Patient and surgeon were interviewed to evaluate the quality of anesthesia. RESULTS: Intrathecal ropivacaine (8 mg alone) produced short sensory anesthesia and motor blockade (132 +/- 38 min and 110 +/- 35 min; mean +/- SD). However, the quality of anesthesia was significantly lower than in any other group (P < 0.05). Ropivacaine (8 mg) plus 75 microg clonidine produced significantly longer sensory and motor anesthesia (195 +/- 40 min and 164 +/- 38 min; P < 0.05). However, this was associated with systemic effects, such as sedation and reduction of arterial blood pressure. Ropivacaine (8 mg) plus 15 microg clonidine did not prolong sensory or motor blockade, afforded high quality anesthesia, and was not associated with detectable systemic effects. CONCLUSION: Small-dose intrathecal clonidine (15 microg) plus 8 mg intrathecal ropivacaine produces adequate and short-lasting anesthesia for knee arthroscopy.     

A new local anesthetic, ropivacaine. Its epidural effects in humans

The current study was initiated to evaluate the epidural anesthetic properties of 0.5%, 0.75%, and 1.0% ropivacaine, a new local anesthetic agent structurally similar to bupivacaine. Fifteen patients scheduled for lower limb orthopedic surgery were enrolled in the study. As the concentration of ropivacaine increased from 0.5% to 1.0%, the time to onset of sensory anesthesia decreased from 6.4 +/- 1.7 (SD) min to 2.4 +/- 0.6 min and the maximum level of sensory anesthesia increased from T6 to T1. These changes were not statistically significant. Time to regression of anesthesia to T12 increased from 255 +/- 73 min with the 0.5% solution to 356 +/- 75 min with 1.0% ropivacaine (P less than 0.05). The degree of motor blockade using the Bromage scale varied with the concentration. When the 0.5% concentration was used, only one patient (20%) had greater than 1+ motor blockade. However, all of the patients receiving the 0.75% or 1.0% solution had at least 2+ motor blockade. Sensory anesthesia was adequate for surgery in 14 of the 15 patients. The mean peak plasma concentration of ropivacaine (Cmax) increased from 0.65 +/- 0.15 micrograms/mL with the 100-mg dose to 1.30 +/- 0.43 microgram/mL with the 200-mg dose. No adverse effects were noted in any patient in the study. These initial studies in humans suggest that ropivacaine provides satisfactory sensory anesthesia with minimal motor blockade at a concentration of 0.5%. An increase in concentration resulted in a more profound motor blockade. The Cmax of ropivacaine in this study was below levels associated with toxicity in animal studies.     

Intrathecal Ropivacaine and Clonidine for Ambulatory Knee Arthroscopy: A Dose-Response Study

Background: The aim of this study was to evaluate the association of a small dose of intrathecal ropivacaine with small doses of intrathecal clonidine for ambulatory surgery.

Methods: One hundred twenty patients, classified as American Society of Anesthesiologists physical status I and scheduled for knee arthroscopy, were studied. Patients were randomly assigned to receive 4 ml of one of the following double-blinded isobaric intrathecal solutions: 8 mg of ropivacaine (group 1; n =30); 8 mg ropivacaine plus 15 [mu]g clonidine (group 2; n =30); 8 mg ropivacaine plus 45 [mu]g clonidine (group 3; n =30); and 8 mg ropivacaine plus 75 [mu]g clonidine (group 4; n =30). The level and duration of sensory anesthesia were recorded, along with the intensity and duration of motor block. Patient and surgeon were interviewed to evaluate the quality of anesthesia.

Results: Intrathecal ropivacaine (8 mg alone) produced short sensory anesthesia and motor blockade (132 +/- 38 min and 110 +/- 35 min; mean +/- SD). However, the quality of anesthesia was significantly lower than in any other group (P < 0.05). Ropivacaine (8 mg) plus 75 [mu]g clonidine produced significantly longer sensory and motor anesthesia (195 +/- 40 min and 164 +/- 38 min;P < 0.05). However, this was associated with systemic effects, such as sedation and reduction of arterial blood pressure. Ropivacaine (8 mg) plus 15 [mu]g clonidine did not prolong sensory or motor blockade, afforded high quality anesthesia, and was not associated with detectable systemic effects.     

Epidural ropivacaine 7.5 mg/ml for elective Caesarean section: A double-blind comparison of efficacy and tolerability with bupivacaine 5 mg/ml

BACKGROUND: Ropivacaine is a new local anaesthetic drug known to be less cardiotoxic than bupivacaine. The aims of this comparative study with bupivacaine were to evaluate efficacy, safety and tolerability for the mother and the neonate when using ropivacaine 7.5 mg/ml for epidural anaesthesia for elective Caesarean section. METHODS: In a double-blind, multicentre trial the patients were randomised to receive 20 ml of either ropivacaine 7.5 mg/ml or bupivacaine 5 mg/ml. The quality of the peroperative analgesia and abdominal muscle relaxation as well as tolerability and safety in both the mother and the neonate were evaluated. RESULTS: A total of 122 patients were evaluated for efficacy and tolerability. There were no significant differences in the onset time and the extent of the sensory spread or motor block. The peroperative quality of anaesthesia and muscle relaxation was similar in both groups. No significant side effects were observed, except for a more profound drop in systolic blood pressure in the ropivacaine group. The anaesthetics were well tolerated by the neonate in both groups, evaluated by Apgar and NACS scores. CONCLUSION: Ropivacaine 7.5 mg/ml administered epidurally resulted in equally effective anaesthesia for Caesarean section as bupivacaine 5 mg/ml. Because of the lower cardiotoxicity of ropivacaine, the new amide has a potential in replacing bupivacaine when used epidurally for Caesarean section.     

Hyperbaric Spinal Ropivacaine: A Comparison to Bupivacaine in Volunteers

Background: Ropivacaine is a newly introduced local anesthetic that may be a useful alternative to low-dose bupivacaine for outpatient spinal anesthesia. However, its relative potency to bupivacaine and its dose-response characteristics are unknown. This double-blind, randomized, crossover study was designed to determine relative potencies of low-dose hyperbaric spinal ropivacaine and bupivacaine and to assess the suitability of spinal ropivacaine for outpatient anesthesia.

Methods: Eighteen healthy volunteers were randomized into three equal groups to receive one spinal administration with bupivacaine and a second with ropivacaine, of equal-milligram doses (4, 8, or 12 mg) of 0.25% drug with 5% dextrose. The duration of blockade was assessed with (1) pinprick, (2) transcutaneous electrical stimulation, (3) tolerance to high tourniquet, (4) electromyography and isometric force dynamometry, and (5) achievement of discharge criteria. Differences between ropivacaine and bupivacaine were assessed with linear and multiple regression. P < 0.05 was considered significant.

Results: Ropivacaine and bupivacaine provided dose-dependent prolongation of sensory and motor block and time until achievement of discharge criteria (R2 ranges from 0.33-0.99; P values from < 0.001 through 0.01). Spinal anesthesia with ropivacaine was significantly different from bupivacaine and was approximately half as potent for all criteria studied. A high incidence of back pain (28%; P = 0.098) was noted after intrathecal ropivacaine was given.