Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2001
Editorial CommentHow can local anesthetic in the wound not help?
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Anesthesia and analgesia · Jan 2001
Randomized Controlled Trial Comparative Study Clinical TrialMinimum local anesthetic volume blocking the femoral nerve in 50% of cases: a double-blinded comparison between 0.5% ropivacaine and 0.5% bupivacaine.
Recent studies demonstrated that ropivacaine was nearly 40% less potent than bupivacaine in the first stage of labor, but contrasting results have been reported. We, therefore, conducted a prospective, randomized, double-blinded study to determine the effects of the ropivacaine/bupivacaine potency ratio on the minimum volume of local anesthetic required to produce effective block of the femoral nerve in 50% of patients. Fifty adults premedicated with IV midazolam, 0.05 mg/kg, undergoing elective knee arthroscopy received femoral nerve blocks with a multiple-injection technique with a nerve stimulator (contractions of vastus medialis, vastus intermedius, and vastus lateralis were elicited with a 0.5-mA stimulating current). Patients randomly received either 0.5% ropivacaine (n = 25) or 0.5% bupivacaine (n = 25). The anesthetic volume was decided according to Dixon's up-and-down method, starting from 12 mL and being equally divided among the three elicited twitches. Successful nerve block was loss of pinprick sensation in the femoral nerve distribution with concomitant block of the quadriceps muscle within 20 min after injection, as assessed by a blinded observer. Positive or negative responses determined a 3-mL decrease or increase for the next patient, respectively. According to the up-and-down sequences, the minimum local anesthetic volume providing successful nerve block in 50% of cases was 14 +/- 2 mL in the ropivacaine group (95% CI: 12-16 mL) and 15 +/- 2 mL (95% CI: 13-17 mL) in the bupivacaine group (P: = 0.155). We conclude that the volume of 0.5% ropivacaine required to produce effective block of the femoral nerve in 50% of patients is similar to that required when using 0.5% bupivacaine. ⋯ Considering the risk for drug-related systemic toxicity, the equipotency ratio between ropivacaine and bupivacaine is crucial for daily practice. Despite the 40% reduction in the analgesic potency of ropivacaine reported during epidural analgesia for labor pain, results of this prospective, randomized, double-blinded study demonstrated that the same volume of 0.5% ropivacaine or 0.5% bupivacaine is required to produce an effective block of the femoral nerve in 50% of cases.
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Anesthesia and analgesia · Jan 2001
Randomized Controlled Trial Comparative Study Clinical TrialTramadol added to lidocaine for intravenous regional anesthesia.
Sixty volunteers, divided into four groups of 15 each, received IV regional anesthesia of the upper limb with 40 mL tramadol 0.25%, sodium chloride 0.9%, lidocaine 0.5%, or 100 mg tramadol-containing lidocaine 0.5%. By using a double-blinded method, we tested the onset and recovery of sensory block at six sites of the forearm and hand as well as onset of complete motor block. The symptoms after deflation of the tourniquet were recorded. The onset and recovery of sensory block and the onset of motor block were similar in the tramadol and saline groups. However, in the Tramadol-Lidocaine Group, the speed of onset of sensory block was faster than in the Lidocaine Group. In the Tramadol and the Tramadol-Lidocaine Groups, the incidence of skin rash and painful or burning sensation at the injection site was increased. We conclude that tramadol 0.25% does not have a local anesthetic effect when used as a sole drug for IV regional anesthesia, but might modify the action of local anesthetic, providing a shorter onset time of sensory block. ⋯ Tramadol, a centrally acting analgesic, might have local anesthetic properties, as do some opioid drugs. We demonstrated that 0.25% tramadol solution containing 100 mg tramadol is not effective as a sole drug, but may improve the action of 0.5% lidocaine for intravenous regional anesthesia. The increased incidence of side effects may limit the clinical use of tramadol.
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Anesthesia and analgesia · Jan 2001
Randomized Controlled Trial Comparative Study Clinical TrialPatient-controlled interscalene analgesia with ropivacaine 0.2% versus bupivacaine 0.15% after major open shoulder surgery: the effects on hand motor function.
We compared the effects of patient-controlled interscalene analgesia with ropivacaine 0.2% and patient-controlled interscalene analgesia (PCIA) with bupivacaine 0.15% on hand grip strength after major open shoulder surgery. Sixty patients scheduled for elective major shoulder surgery were prospectively randomized to receive in a double-blinded fashion either ropivacaine or bupivacaine through an interscalene catheter. Before surgery, all patients received an interscalene block (ISB) with either 40 mL of 0.6% ropivacaine or 40 mL of 0.5% bupivacaine. Six h after ISB, the patients received a continuous infusion of either 0.2% ropivacaine or 0.15% bupivacaine for 48 h. In both groups, the PCIA infusion rate was 5 mL/h plus a bolus of 4 mL with a lockout time of 20 min. Strength in the hand was assessed preoperatively, 24 h, and 48 h after ISB and 6 h after stopping the infusion of local anesthetic. The presence of paresthesia in the fingers was checked. Pain relief was assessed using a visual analog scale; side effects were noted, and the patients rated their satisfaction 54 h after the block. A significant decrease of strength in the hand was observed in the Bupivacaine group 24, 48, and 54 h after ISB (P < 0.05). Paresthesia was more frequently reported in the Bupivacaine group for the second and third fingers 48 h after ISB (P < 0.05) and in the first three fingers 6 h after discontinuation of the local anesthetic infusion (P: < 0.05). The pain score was similar in the two groups at all times, and patient satisfaction was comparable between the two groups. We conclude that the use of the PCIA technique with ropivacaine 0.2% or bupivacaine 0.15% provides a similar pain relief after major shoulder surgery. However, ropivacaine 0.2% is associated with better preservation of strength in the hand and less paresthesia in the fingers. ⋯ We compared the patient-controlled interscalene analgesia technique with ropivacaine 0.2% and bupivacaine 0.15% after major open shoulder surgery. For similar pain control ropivacaine is associated with better preservation of strength in the hand and less paresthesia in the fingers.
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Anesthesia and analgesia · Jan 2001
Randomized Controlled Trial Comparative Study Clinical TrialA comparison between meperidine, clonidine and urapidil in the treatment of postanesthetic shivering.
Postanesthetic shivering can be treated with many types of drugs. We compared the effects of meperidine, clonidine, and urapidil on postanesthetic shivering. Sixty patients shivering during recovery from general anesthesia were treated in a randomized, double-blinded fashion with 25 mg meperidine IV, 0.15 mg clonidine IV, or 25 mg urapidil IV in three separate groups of 20 patients each. If shivering did not stop within 5 min, the treatment was repeated once; clonidine was replaced with saline for the second dose. Rectal temperature, arterial blood pressure, heart rate, SaO(2) and vigilance were monitored. Clonidine stopped shivering in all 20 patients. A single dose of meperidine stopped the shivering in 18 of 20 patients, with the other 2 patients needing a second dose. Urapidil was less effective: the first dose stopped the shivering in only six patients; the second dose was effective in another six; the drug was ineffective in 8 of 20 patients. Meperidine and clonidine were both nearly 100% effective in treating postanesthetic shivering without negative side effects. By comparison, urapidil was only effective in 60% of patients treated (P <0.01). ⋯ Patients shivering during recovery from general anesthesia were treated in a randomized double-blinded fashion with meperidine, clonidine, or urapidil. Meperidine and clonidine were both very effective, whereas urapidil was only effective in 60% of patients treated.