Bilateral intravenous regional anesthesia: a new method to test additives to local anesthetic solutions

BACKGROUND: Ketorolac, when added to lidocaine, has been shown to reduce early tourniquet pain during intravenous regional anesthesia (i.v.RA) in patients. Although the effectiveness of ropivacaine 0.2% for i.v.RA is equal to that of lidocaine 0.5% but significantly reduces central nervous system side effects after release of the tourniquet, it provides no advantage with regard to tourniquet tolerance times. Simultaneous bilateral i.v.RA with ropivacaine 0.2% was used to test the hypothesis that ketorolac modifies tourniquet tolerance and to test whether drug combinations can be evaluated in one study session. METHODS: Ten healthy, unsedated volunteers received 30 ml of ropivacaine 0.2% in each upper arm with 2 ml of normal saline in one arm and 30 mg of ketorolac in the contralateral arm for i.v.RA. Both proximal tourniquets remained inflated for 30 min, followed by inflation of the distal tourniquets and release of the proximal ones. Verbal numeric scores for tourniquet pain were recorded for both extremities. Central nervous system side effects were graded after release of each distal tourniquet. RESULTS: There was no difference between the two upper extremities with regard to surgical anesthesia and tourniquet tolerance. Total tourniquet tolerance was a median of 58.5 min (range, 45-90 min) and 60.5 min (39-79 min) in the normal saline and ketorolac groups, respectively. After release of the distal tourniquets, 5 of 10 volunteers experienced mild dizziness. CONCLUSIONS: The addition of ketorolac to ropivacaine does not improve tourniquet tolerance. Minimal central nervous system side effects after tourniquet release suggest that a total of 60 ml ropivacaine 0.2% for bilateral i.v.RA is a useful model for comparison of i.v.RA drug combinations.     

Comparison of ropivacaine 0.2% and lidocaine 0.5% for intravenous regional anesthesia in volunteers.

A longer acting local anesthetic such as ropivacaine may offer advantages over lidocaine for IV regional anesthesia (IVRA). The objective of this investigation was to determine whether the use of ropivacaine improves the quality and duration of IVRA. In a randomized, double cross-over design, 10 volunteers received lidocaine 0.5% or ropivacaine 0.2% for IVRA of the upper extremity on two separate days with a standard double-cuff technique. Sensation to pinprick, response to tetanic stimuli, and tourniquet pain were assessed on a 0-10 verbal numeric score scale at 5-min intervals throughout the period of tourniquet inflation. Motor function was evaluated by grip strength. After release of the second (distal) cuff, pinprick sensation, motor strength, and systemic side effects were evaluated at 3, 10, and 30 min. No significant differences were observed for onset times of anesthesia and times to proximal (38 +/- 3 and 36 +/- 3 min) or distal (34 +/- 13 and 36 +/- 13 min) tourniquet release after the administration of ropivacaine and lidocaine, respectively. However, postdeflation hypoalgesia and motor blockade were prolonged with ropivacaine, and postdeflation light-headedness, tinnitus, and drowsiness were more prominent with lidocaine. We conclude that ropivacaine may be an alternative to lidocaine for IVRA. It may result in prolonged analgesia and fewer side effects after tourniquet release. IMPLICATIONS: In this study, volunteers received lidocaine 0.5% or ropivacaine 0.2% for IV regional anesthesia on two study days. Ropivacaine and lidocaine provided similar surgical conditions. However, after release of the distal tourniquet, prolonged sensory blockade and fewer central nervous system side effects were observed with ropivacaine.     

Central nervous system side effects are less important afteriv regional anesthesia with ropivacaine 0.2% compared to lidocaine 0.5% in volunteers

PURPOSE: Following release of a double tourniquet for intravenous regional anesthesia (IVRA), ropivacaine was shown to have a longer duration of action and less central nervous system (CNS) side effects than lidocaine. This study examines the correlation of CNS side effects to plasma levels of lidocaine 0.5% and ropivacaine 0.2% when injected intravenously for IVRA. METHODS: In a double-blind, cross-over study, ten volunteers received IVRA with 40 mL ropivacaine 0.2% or lidocaine 0.5% at least four days apart. Both cuffs of a double-cuff tourniquet remained inflated until they could no longer be tolerated. The incidence, duration and intensity of CNS side effects were recorded at three, ten, and 30 min after tourniquet release and correlated with simultaneous venous blood samples. RESULTS: There was a lower incidence of CNS side effects with ropivacaine (6/10 volunteers) when compared to lidocaine (10/10 volunteers). There was also less duration of these side effects (mean +/- SD, 5.1 +/- 5.2 min vs 11.7 +/- 6.7 min). Measured total plasma levels were highest at ten minutes with ropivacaine 0.2% (1.2 +/- 0.3 microg.mL(-1)) and at three minutes with lidocaine 0.5% (1.7 +/- 0.6 microg.mL(-1)). Peak CNS symptoms correlated with measured venous plasma levels for lidocaine, but occurred earlier with ropivacaine. CONCLUSIONS: We observed a lower incidence of CNS side effects with ropivacaine as compared to lidocaine. Although ropivacaine's greater lipid solubility should, theoretically, lead to more CNS side effects, this was, likely, offset by slower release from tissues and lesser percentage of unbound (free) drug.     

An evaluation of the analgesic efficacy of intravenous regional anesthesia with lidocaine and ketorolac using a forearm versus upper arm tourniquet

Intravenous regional anesthesia (IVRA) using a forearm tourniquet may be a potentially safer technique compared with using an upper arm tourniquet. Ketorolac is a useful adjuvant to lidocaine for IVRA. In this study, we assessed the analgesic efficacy of administering IVRA lidocaine and ketorolac with either a forearm or upper arm tourniquet for outpatient hand surgery. Upper arm IVRA was established using 40 mL of a solution containing 200 mg of lidocaine and ketorolac 20 mg (0.5 mg/mL). Forearm IVRA was established using 20 mL of a solution containing 100 mg of lidocaine and ketorolac 10 mg (0.5 mg/mL). Onset and duration of sensory block as well as postoperative pain and analgesic use were recorded. The patients who received forearm IVRA had a significantly longer period during which they required no analgesics (701 +/- 133 min) compared with 624 +/- 80 min for the upper arm IVRA ketorolac patients (P = 0.032). Onset of sensory block was similar between the two groups; however, recovery of sensation was significantly longer in the Forearm IVRA (22 +/- 5 min) group compared with the Upper Arm IVRA (13 +/- 3 min) group (P < 0.05). There were no differences in postoperative analgesic use or pain scores between the two groups. We conclude that forearm IVRA with lidocaine and ketorolac provides safe and effective perioperative analgesia for patients undergoing ambulatory hand surgery. This technique results in a longer duration of sensory block and prolonged postoperative analgesia compared with upper arm IVRA while using one-half the doses of both lidocaine and ketorolac. IMPLICATIONS: Forearm tourniquet intravenous regional anesthesia (IVRA) with 50% less lidocaine and ketorolac provides for both a longer duration of sensory block and prolonged postoperative analgesia compared with upper arm IVRA.     

Levobupivacaine 0.125% and lidocaine 0.5% for intravenous regional anesthesia in volunteers

BACKGROUND: Levobupivacaine, a long acting, amino-amide, local anesthetic, may offer advantages over lidocaine for intravenous regional anesthesia (IVRA). The objective of this investigation was to compare levobupivacaine to lidocaine for IVRA. METHODS: After institutional review board approval and informed consent, eight unpremedicated male American Society of Anesthesiologists (ASA) I-II volunteers received 40 ml of levobupivacaine 0.125% or lidocaine 0.5% for IVRA on separate days. Onset and regression of sensory anesthesia by pinprick, transcutaneous electrical stimulation (TES), and of motor function were tested before, during, and after release of the tourniquet. Central nervous system and cardiac side effects were evaluated after local anesthetic administration and tourniquet release. The tourniquet remained inflated for 30-45 min. RESULTS: Intravenous regional anesthesia with either agent provided surgical anesthesia. Sensory anesthesia to pinprick (lateral antebrachial cutaneous nerve) was faster with lidocaine at median 1.5 min. versus 12.5 min with levobupivacaine. Loss of sensation to TES occurred at median 22.5 and 27.5 min for lidocaine and levobupivacaine, respectively. Loss of motor function occurred earlier after lidocaine administration. After release of the tourniquet, return of sensation to TES, pinprick (ulnar nerve), and return of motor function occurred later with levobupivacaine at median 25, 15, and 21.25 versus 10, 4.5, and 10 min with lidocaine. Central nervous system side effects were absent in volunteers given levobupivacaine, but five of eight volunteers given lidocaine experienced mild side effects. No cardiac events were noted. CONCLUSIONS: Levobupivacaine 0.125% may be an alternative to lidocaine 0.5% for IVRA. Longer lasting analgesia after release of the tourniquet may be caused by a more profound and prolonged tissue binding effect of levobupivacaine.     

Levobupivacaine 0.125% and Lidocaine 0.5% for Intravenous Regional Anesthesia in Volunteers

Background: Levobupivacaine, a long acting, amino-amide, local anesthetic, may offer advantages over lidocaine for intravenous regional anesthesia (IVRA). The objective of this investigation was to compare levobupivacaine to lidocaine for IVRA.

Methods: After institutional review board approval and informed consent, eight unpremedicated male American Society of Anesthesiologists (ASA) I-II volunteers received 40 ml of levobupivacaine 0.125% or lidocaine 0.5% for IVRA on separate days. Onset and regression of sensory anesthesia by pinprick, transcutaneous electrical stimulation (TES), and of motor function were tested before, during, and after release of the tourniquet. Central nervous system and cardiac side effects were evaluated after local anesthetic administration and tourniquet release. The tourniquet remained inflated for 30-45 min.

Results: Intravenous regional anesthesia with either agent provided surgical anesthesia. Sensory anesthesia to pinprick (lateral antebrachial cutaneous nerve) was faster with lidocaine at median 1.5 min. versus 12.5 min with levobupivacaine. Loss of sensation to TES occurred at median 22.5 and 27.5 min for lidocaine and levobupivacaine, respectively. Loss of motor function occurred earlier after lidocaine administration. After release of the tourniquet, return of sensation to TES, pinprick (ulnar nerve), and return of motor function occurred later with levobupivacaine at median 25, 15, and 21.25 versus 10, 4.5, and 10 min with lidocaine. Central nervous system side effects were absent in volunteers given levobupivacaine, but five of eight volunteers given lidocaine experienced mild side effects. No cardiac events were noted.     

Comparison of ropivacaine 0.2% and 0.25% with lidocaine 0.5% for intravenous regional anesthesia

Study ObjectiveTo compare the anesthetic effects of two different concentrations and doses of ropivacaine (0.2% and 0.25%) with those of a conventional dose of lidocaine 0.5%.DesignProspective, randomized, double-blinded, clinical investigation.SettingLarge metropolitan university hospital.Patients66 adult ASA physical status I and II patients undergoing forearm and hand surgery.InterventionsPatients were randomly allocated to three groups to receive intravenous regional anesthesia (IVRA). Study groups were: ropivacaine 0.2% (Group I, n = 22), ropivacaine 0.25% (Group II, n = 22), and lidocaine 0.5% (Group III, n = 22).MeasurementsTourniquet tolerance times and regression of sensory analgesia were noted. Verbal numerical pain scores (VNS), cumulative analgesic consumption, and side effects were recorded during surgery and postanesthesia care unit (PACU). Time to first pain medication intake and number of patients receiving analgesics in the PACU were recorded.Main ResultsAdditional tolerance times for the distal tourniquet were significantly higher in the ropivacaine 0.25% group than the other two groups. Regression of sensory anesthesia was fastest in the lidocaine group. During the PACU stay, VNSs were significantly lower in the first 20 minutes in the ropivacaine groups than the lidocaine group. Time to first intake of pain medication in the PACU was soonest in the lidocaine group. The number of patients given analgesics in the PACU was highest in the lidocaine group. The number of patients taking > two tablets of tramadol was significantly lowest in the ropivacaine 0.25% group. No serious side effects were observed in any study group.ConclusionLonger tolerance times for the distal tourniquet, prolonged analgesia after tourniquet release, and lower analgesic requirements postoperatively make ropivacaine 0.2% and 0.25% an alternative to lidocaine for IVRA.     

Quantitative comparison of leakage under the tourniquet in forearm versus conventional intravenous regional anesthesia

We compared the quantitative leakage between forearm and conventional IV regional anesthesia (IVRA). Forearm IVRA remains unpopular because of the theoretical risk of local anesthetic leakage through the interosseous vessels. IVRA was simulated on the forearm or arm during two separate, randomized sessions using a double tourniquet in 14 volunteers. A radiolabeled substance, DISIDA (99m Tc-disofenin) with a structure similar to lidocaine, was injected instead of local anesthetic. Volumes of 0.4 mL/kg (maximum 25 mL), were used for forearm IVRA and 0.6 mL/kg (maximum 45 mL) for conventional IVRA. A gamma camera recorded radioactivity levels in the limb distal to the tourniquet every 30 s while the tourniquet was inflated (25 min) and for 20 min postdeflation. The leakage of radiolabeled substance during inflation was similar in both groups, 6%+/-12% (mean +/- SD) from the forearm and 10%+/-20% from the upper arm. After deflation, mean loss of radioactivity was higher in conventional IVRA, 70%+/-7% vs 57%+/-11% and 82%+/-5% vs 69%+/-11% at 3 and 20 min, respectively (P < 0.001). We conclude that forearm IVRA results in tourniquet leakage comparable to conventional IVRA and is potentially safer because the required dose of local anesthetic is smaller. IMPLICATIONS: Using a tourniquet on the forearm for IV regional anesthesia does not increase the risk of drug leakage. This is potentially a safer technique compared with conventional IV regional anesthesia because a much smaller dose of local anesthetic is required.     

Lidocaine priming reduces tourniquet pain during intravenous regional anesthesia: A preliminary study

BACKGROUND AND OBJECTIVES: Tourniquet pain often limits the use of intravenous regional anesthesia (IVRA). Intravenous (IV) lidocaine has been shown to be effective in the management of acute and neuropathic pains. We tested the hypothesis that a priming IV injection of lidocaine might have an analgesic effect on tourniquet pain during IVRA. METHODS: A prospective, randomized, double- blind study was conducted on 40 patients scheduled for carpal tunnel decompression. No sedation was given. Each patient received either 1 mg/kg of IV lidocaine (group L) or 0.1 mL/kg of IV isotonic saline (group control = C) 5 minutes before IVRA. Thereafter, they received 3 mg/kg of plain 0.5 % lidocaine into the isolated and exsanguinated arm. A double-cuffed tourniquet was used. Pain at the tourniquet and the surgical sites was assessed every 5 minutes using a linear visual analog scale (VAS) and a verbal rating scale (VRS) during the surgical procedure and the immediate postoperative period (60 minutes). RESULTS: Demographic data and duration of proximal and distal tourniquet were similar in each group. Significant differences in the pain scales were observed for the distal tourniquet at tourniquet inflation time and 15 minutes after (P =.03 and.005, respectively) in the group L. For the proximal tourniquet, only the VRS was significantly improved (P =.03). No analgesic benefit was observed in the immediate postoperative period. CONCLUSIONS: Priming IV lidocaine when compared with isotonic saline is effective in reducing tourniquet pain in IVRA.     

Comparison of ropivacaine and lidocaine for intravenous regional anesthesia in volunteers: a preliminary study on anesthetic efficacy and blood level.

BACKGROUND: Ropivacaine may be useful for intravenous regional anesthesia, but its anesthetic effectiveness and toxicity have not been evaluated. METHODS: Two doses of ropivacaine (1.2 and 1.8 mg/kg) and one dose of lidocaine (3 mg/kg) were compared for intravenous regional anesthesia in 15 volunteers. An arm tourniquet was inflated for 30 min after injection and then deflated in two cycles. Sensory block was measured by response to touch, cold, pinprick, and transcutaneous electric stimulation, and motor function was measured by hand grip strength and muscle power. Median, ulnar, radial, and musculocutaneous nerve functions were tested before local anesthetic injection and then at 5-min intervals until blocks resolved. The plasma ropivacaine and lidocaine concentrations were determined from arterial and venous blood samples drawn from the unanesthetized arm. RESULTS: Sensory and motor blocks were complete within 25 min and 30 min, respectively, in all three treatment groups. However, recovery of sensory and motor block after tourniquet release was slowest in the high-dose ropivacaine group. Anesthesia to pinprick and transcutaneous electric stimulation was sustained in all the volunteers in the high-dose ropivacaine group for 55 min and 85 min, respectively, whereas complete recovery was observed in the lidocaine group (P = 0.008) and partial recovery in the low-dose ropivacaine group (P < 0.05) during the same period. Motor block also was sustained in the high-dose ropivacaine group for 70 min, which was significantly longer than in the lidocaine group (P < 0.05). All volunteers (five of five) given lidocaine and one volunteer given high-dose ropivacaine reported light-headedness and hearing disturbance during tourniquet release when the arterial plasma lidocaine and ropivacaine concentrations were 4.7+/-2.1 microg/ml (mean) and 2.7 micro/ml, respectively. CONCLUSION: Compared with lidocaine, intravenous regional anesthesia with ropivacaine appears to be comparable but has longer-lasting residual anesthesia.     

Adding clonidine to lidocaine for intravenous regional anesthesia prevents tourniquet pain.

Tourniquet pain often complicates the use of the pneumatic tourniquet during surgical procedures performed under IV regional anesthesia. Clonidine-containing local anesthetic solutions have better analgesic properties than plain solutions when used for spinal, epidural, or peripheral blocks. We tested the hypothesis that the addition of clonidine may improve the quality of IV regional anesthesia, especially tourniquet tolerance. Forty patients were allocated randomly in a double-blinded, randomized study to receive 40 mL of 0.5% lidocaine and either 1 mL of isotonic saline or clonidine (150 microg). A double-cuffed tourniquet was kept inflated until patients complained of pain, leading to release of the distal cuff. Pain at the tourniquet site, at the surgical site, and in the distal part of the arm was rated on a visual analog scale (VAS) and a verbal rating scale (VRS) every 15 min during tourniquet placement and every 15 min for 1 h after tourniquet deflation. Motor blockade, sedation, arterial pressure, and heart rate were also recorded. VAS and VRS scores were significantly lower in the clonidine group 30 and 45 min after tourniquet inflation. The tolerance for the distal tourniquet was also significantly longer in the clonidine group (median [range]: 22 [10-40] vs 10 [5-20] min; P < 0.05); motor blockade was comparable between the two groups. Pain was not different in the two groups after tourniquet release. The clonidine group experienced a higher degree of sedation. We conclude that clonidine improves tourniquet tolerance when added to a local anesthetic solution. IMPLICATIONS: A 150-microg dose of clonidine added to lidocaine improved tourniquet tolerance during IV regional anesthesia.     

Adding dexmedetomidine to lidocaine for intravenous regional anesthesia

Dexmedetomidine is approximately 8 times more selective toward the alpha-2-adrenoceptors than clonidine. It decreases anesthetic requirements by up to 90% and induces analgesia in patients. We designed this study to evaluate the effect of dexmedetomidine when added to lidocaine in IV regional anesthesia (IVRA). We investigated onset and duration of sensory and motor blocks, the quality of the anesthesia, intraoperative-postoperative hemodynamic variables, and intraoperative-postoperative pain and sedation. Thirty patients undergoing hand surgery were randomly assigned to 2 groups to receive IVRA. They received 40 mL of 0.5% lidocaine and either 1 mL of isotonic saline (group L, n = 15) or 0.5 microg/kg dexmedetomidine (group LD, n = 15). Sensory and motor block onset and recovery times and anesthesia quality were noted. Before and after the tourniquet application at 5, 10, 15, 20, and 40 min, hemodynamic variables, tourniquet pain and sedation, and analgesic use were recorded. After the tourniquet deflation, at 30 min, and 2, 4, 6, 12, and 24 h, hemodynamic variables, pain and sedation values, time to first analgesic requirement, analgesic use, and side effects were noted. Shortened sensory and motor block onset times, prolonged sensory and motor block recovery times, prolonged tolerance for the tourniquet, and improved quality of anesthesia were found in group LD. Visual analog scale scores were significantly less in group LD in the intraoperative period and 30 min, and 2, 4, and 6 h after tourniquet release. Intra-postoperative analgesic requirements were significantly less in group LD. Time to first analgesic requirements was significantly longer in group LD in the postoperative period. We conclude that the addition of 0.5 microg/kg dexmedetomidine to lidocaine for IVRA improves quality of anesthesia and perioperative analgesia without causing side effects. IMPLICATIONS: This study was designed to evaluate the effect of dexmedetomidine when added to lidocaine for IV regional anesthesia. This is the first clinical study demonstrating that the addition of 0.5 microg/kg dexmedetomidine to lidocaine for IV regional anesthesia improves quality of anesthesia and intraoperative-postoperative analgesia without causing side effects.     

Comparison of Ropivacaine and Lidocaine for Intravenous Regional Anesthesia in Volunteers: A Preliminary Study on Anesthetic Efficacy and Blood Level

Background: Ropivacaine may be useful for intravenous regional anesthesia, but its anesthetic effectiveness and toxicity have not been evaluated.

Methods: Two doses of ropivacaine (1.2 and 1.8 mg/kg) and one dose of lidocaine (3 mg/kg) were compared for intravenous regional anesthesia in 15 volunteers. An arm tourniquet was inflated for 30 min after injection and then deflated in two cycles. Sensory block was measured by response to touch, cold, pinprick, and transcutaneous electric stimulation, and motor function was measured by hand grip strength and muscle power. Median, ulnar, radial, and musculocutaneous nerve functions were tested before local anesthetic injection and then at 5-min intervals until blocks resolved. The plasma ropivacaine and lidocaine concentrations were determined from arterial and venous blood samples drawn from the unanesthetized arm.

Results: Sensory and motor blocks were complete within 25 min and 30 min, respectively, in all three treatment groups. However, recovery of sensory and motor block after tourniquet release was slowest in the high-dose ropivacaine group. Anesthesia to pinprick and transcutaneous electric stimulation was sustained in all the volunteers in the high-dose ropivacaine group for 55 min and 85 min, respectively, whereas complete recovery was observed in the lidocaine group (P = 0.008) and partial recovery in the low-dose ropivacaine group (P < 0.05) during the same period. Motor block also was sustained in the high-dose ropivacaine group for 70 min, which was significantly longer than in the lidocaine group (P < 0.05). All volunteers (five of five) given lidocaine and one volunteer given high-dose ropivacaine reported light-headedness and hearing disturbance during tourniquet release when the arterial plasma lidocaine and ropivacaine concentrations were 4.7 +/- 2.1 [micro sign]g/ml (mean) and 2.7 [micro sign]/ml, respectively.     

Clonidine versus ketamine to prevent tourniquet pain during intravenous regional anesthesia with lidocaine

BACKGROUND AND OBJECTIVES: Both clonidine and ketamine have been found to prolong the action of local anesthetics through a peripheral mechanism. Our study compares the efficacy of a low dose of clonidine or ketamine separately added to intravenous regional anesthesia (IVRA) with lidocaine to prevent tourniquet pain. METHODS: We conducted a prospective randomized double-blinded study in 45 patients undergoing hand or forearm surgery, with anticipated duration exceeding 1 hour under IVRA. Proximal cuff inflation of a double tourniquet was followed by administration of 40 mL of lidocaine 0.5% and either saline, 1 microg/kg clonidine, or 0.1 mg/kg ketamine. When anesthesia was established, the inflation of the proximal and distal cuff was interchanged. Thereafter, tourniquet pain was rated on a visual analog scale (VAS) every 10 minutes. Intraoperatively, boluses of 25 microg fentanyl were provided for tourniquet pain treatment when required, and total fentanyl consumption was recorded. RESULTS: Patients receiving plain lidocaine persistently reported the highest pain scores among groups (P <.001) 20 minutes after distal cuff inflation. Differences between the groups with additional treatment were noted 50 minutes after distal cuff inflation and until the end of the observation, with significantly lower VAS ratings (P <.001 to P <.01) in ketamine-treated patients. Total fentanyl consumption was significantly decreased by ketamine (70.00 +/- 25.35 microg) or clonidine (136.67 +/- 39.94 microg) compared with the plain lidocaine group (215.33 +/- 52.33 microg) (P <.001 between all groups). CONCLUSIONS: The addition of clonidine 1 microg/kg or ketamine 0.1 mg/kg to lidocaine for IVRA delays the onset of unbearable tourniquet pain and decreases analgesic consumption for tourniquet pain relief, although ketamine has a more potent effect.     

Ropivacaine 0.2% and Lidocaine 0.5% for Intravenous Regional Anesthesia in Outpatient Surgery

Background: A longer-acting local anesthetic agent, such as ropivacaine, may offer advantages over lidocaine for intravenous regional anesthesia. The objectives of this study were to evaluate whether the findings of volunteer investigations with intravenous regional anesthesia with ropivacaine (which have shown prolonged analgesia after release of the tourniquet) translates into improved pain control after surgery.

Methods: With Human Investigation Committee approval and a double-blind study design, 20 healthy patients with American Society of Anesthesiologists physical status I or II classification who were scheduled to undergo forearm and hand surgery were randomly assigned to administration of 40 ml of either 0.2% ropivacaine or 0.5% lidocaine for intravenous regional anesthesia. Evidence of central nervous system side effects, such as lightheadedness, tinnitus, and metallic taste, as well as cardiac arrhythmias, were evaluated and treated (if necessary) after local anesthetic administration, before and during surgery, and after release of the tourniquet until discharge from the postanesthesia care unit. Regression of sensory anesthesia in the nerve distributions of the forearm and hand was recorded. Verbal numerical pain scores were monitored and quantified until the patients were discharged to home from the postanesthesia care unit. Patient pain scores, side effect profiles, time to first oral intake, and total amount of oral analgesics were recorded 24 h postoperatively.

Results: Intravenous regional anesthesia with 0.2% ropivacaine and 0.5% lidocaine provided equivalent levels of surgical anesthesia. After release of the tourniquet, the first evidence for return of sensation in the distribution of the five peripheral nerves occurred later in the ropivacaine group (median, 20 min; range, 15-40 min) than in the lidocaine group (median, 1 min; range, 1-25 min). Verbal numerical pain scores were significantly lower at the time of admission, whereas during the remainder of the postanesthesia care unit stay and later at home, the difference in verbal numerical pain scores between the two groups was no longer statistically significant.     

Forearm rescue cuff improves tourniquet tolerance during intravenous regional anesthesia

BACKGROUND AND OBJECTIVES: Tourniquet pain during intravenous regional anesthesia (IVRA) of the upper limb is common and can limit tourniquet inflation time. We hypothesize that a forearm rescue cuff is better tolerated than the traditional rescue cuff of a double-cuff tourniquet. METHODS: After Institutional Review Board (IRB) approval and informed consent, 10 healthy unmedicated volunteers took part in a prospective, randomized, cross-over study. Following inflation of the proximal tourniquet cuff on the upper arm, a standardized IVRA with 0.5% lidocaine, 0.6 mL/kg was administered. When the volunteer complained of tourniquet pain, or at 30 minutes, the initial cuff was changed to a rescue cuff. During session A, the rescue cuff was the traditional distal cuff of the double-cuff tourniquet. During session B, a single forearm cuff was used. When the volunteer experienced the same level of tourniquet pain, the rescue cuff was deflated and the study session ended. The tourniquet time for the rescue cuff, the visual analog scale (VAS) pain score, and the incidence and duration of side effects were recorded. RESULTS: The forearm rescue cuff was tolerated significantly longer than the arm rescue cuff (49 +/- 15 v 29 +/- 11 minutes, 95% confidence interval [CI] 7 to 32 minutes, P 相似文献   

Ropivacaine 0.2% and lidocaine 0.5% for intravenous regional anesthesia in outpatient surgery

BACKGROUND: A longer-acting local anesthetic agent, such as ropivacaine, may offer advantages over lidocaine for intravenous regional anesthesia. The objectives of this study were to evaluate whether the findings of volunteer investigations with intravenous regional anesthesia with ropivacaine (which have shown prolonged analgesia after release of the tourniquet) translates into improved pain control after surgery. METHODS: With Human Investigation Committee approval and a double-blind study design, 20 healthy patients with American Society of Anesthesiologists physical status I or II classification who were scheduled to undergo forearm and hand surgery were randomly assigned to administration of 40 ml of either 0.2% ropivacaine or 0.5% lidocaine for intravenous regional anesthesia. Evidence of central nervous system side effects, such as lightheadedness, tinnitus, and metallic taste, as well as cardiac arrhythmias, were evaluated and treated (if necessary) after local anesthetic administration, before and during surgery, and after release of the tourniquet until discharge from the postanesthesia care unit. Regression of sensory anesthesia in the nerve distributions of the forearm and hand was recorded. Verbal numerical pain scores were monitored and quantified until the patients were discharged to home from the postanesthesia care unit. Patient pain scores, side effect profiles, time to first oral intake, and total amount of oral analgesics were recorded 24 h postoperatively. RESULTS: Intravenous regional anesthesia with 0.2% ropivacaine and 0.5% lidocaine provided equivalent levels of surgical anesthesia. After release of the tourniquet, the first evidence for return of sensation in the distribution of the five peripheral nerves occurred later in the ropivacaine group (median, 20 min; range, 15-40 min) than in the lidocaine group (median, 1 min; range, 1-25 min). Verbal numerical pain scores were significantly lower at the time of admission, whereas during the remainder of the postanesthesia care unit stay and later at home, the difference in verbal numerical pain scores between the two groups was no longer statistically significant. CONCLUSIONS: Ropivacaine 0.2% may be an alternative to 0.5% lidocaine for intravenous regional anesthesia in the outpatient surgical setting. Longer-lasting analgesia in the immediate postoperative period may be due to a more profound and prolonged tissue binding effect of ropivacaine.     

Intravenous regional anesthesia using lidocaine and magnesium

We conducted this study to evaluate the effects of magnesium, when added to lidocaine for IV regional anesthesia (IVRA), on tourniquet pain. Thirty patients undergoing elective hand surgery during IVRA were randomly assigned to two groups. IVRA was achieved with 10 mL of saline plus 3 mg/kg lidocaine 0.5% diluted with saline to a total of 40 mL in group C or with 10 mL of 15% magnesium sulfate (12.4 mmol) plus 3 mg/kg lidocaine 0.5% diluted with saline to a total of 40 mL in group M. Injection pain, sensory and motor block onset and recovery time, tourniquet pain, and anesthesia quality were noted. Patients were instructed to receive 75 mg of IM diclofenac when the visual analog scale (VAS) score was >4, and analgesic requirements were recorded. Sensory and motor block onset times were shorter and recovery times were prolonged in group M (P < 0.05). VAS scores of tourniquet pain were lower in group M at 15, 20, 30, 40, and 50 min (P < 0.001). Anesthesia quality, as determined by the anesthesiologist and surgeon, was better in group M (P < 0.05). Time to the first postoperative analgesic request in group C was 95 +/- 29 min and in group M was 155 +/- 38 min (P < 0.05). Postoperative VAS scores were higher for the first postoperative 6 h in group C (P < 0.05). Diclofenac consumption was significantly less in group M (50 +/- 35 mg) when compared with group C (130 + 55 mg) (P < 0.05). We conclude that magnesium as an adjunct to lidocaine improves the quality of anesthesia and analgesia in IVRA.     

Effect of clonidine on upper extremity tourniquet pain in healthy volunteers

BACKGROUND AND OBJECTIVES: Tourniquet pain is often a limiting factor during intravenous regional anesthesia (IVRA). The purpose of this study was to evaluate the efficacy of 1 microg/kg of clonidine added to IVRA-lidocaine in decreasing the onset of severe tourniquet pain. METHODS: Upper extremity IVRA was performed in 15 volunteers with a double-cuffed tourniquet on 2 separate occasions at least 1 week apart. IVRA was established with either 40 mL 0.5% lidocaine (IVRA-L) or 40 mL 0.5% lidocaine with 1 microg/kg clonidine (IVRA-Cl). Verbal pain scores (VPS) from 0 to 10 were recorded every 5 minutes. When the VPS reached 6, the distal cuff was inflated, and the proximal cuff was deflated. This was defined as the first tourniquet time (T1). The study was terminated at a VPS of 10, or at 60 minutes, whichever occurred first. The time from distal cuff inflation to deflation was defined as the second tourniquet time (T2). Total tourniquet time (TT) was the sum of T1 and T2. RESULTS: T1 for IVRA-L (21.6 +/- 3.9) and IVRA-Cl (22.7 +/- 2.7) were not significantly different. T2 and TT were significantly longer (P < .0001; P < .0007, respectively) for IVRA-Cl (33.0 +/- 6.2; 55.6 +/- 6.6) than for IVRA-L (25.5 +/- 4.4; 47.1 +/- 5.2). CONCLUSION: This study shows that the addition of 1 microg/kg of clonidine to 40 mL of 0.5% IVRA-L delays the onset time of tourniquet pain in healthy, unsedated volunteers.     

A prospective,randomized, controlled trial of forearm versus upper arm tourniquet tolerance

This prospective, randomized, controlled trial studied the duration of upper and forearm tourniquet tolerance in 24 fit, healthy volunteers. Upper arm and forearm tourniquets were applied to either arm and inflated simultaneously. The time to request for deflation was recorded for each tourniquet. The mean tolerance for the upper arm tourniquet was 18 (range 10-26) min and for the forearm tourniquet was 25 (range 12-52) min. Under the conditions of this study, forearm tourniquets were tolerated for a mean of 7 min longer than upper arm tourniquets. The increase in tourniquet time afforded by a forearm tourniquet is clinically important in hand surgery performed under local anaesthetic.