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.     

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.     

Comparison of ropivacaine 2 mg ml(-1) and prilocaine 5 mg ml(-1) for i.v. regional anaesthesia in outpatient surgery

Background. Ropivacaine 2 mg ml^–1 (0.2%) provides longer-lastinganalgesia after deflation of the tourniquet cuff, with fewerside-effects, than lidocaine 5 mg ml^–1 (0.5%) after i.v.regional anaesthesia (IVRA). Whether ropivacaine 2 mg ml^–1also exerts this advantage over prilocaine 5 mg ml^–1,the local anaesthetic of choice in IVRA in most European countrieswas investigated in this study. Methods. Sixty outpatients scheduled for forearm or hand surgeryreceived IVRA with 40 ml of ropivacaine 2 mg ml^–1 (Ropi)or prilocaine 5 mg ml^–1 (Prilo) in a randomized, double-blindedfashion. The development and recovery of pin-prick analgesiaand motor power of the hand, as well as ropivacaine and prilocaineplasma concentrations (n=30), were assessed during and afteroperation. Results. Anaesthesia for surgery was adequate in both groups.Pin-prick analgesia was achieved at a similar rate, except inthe radial nerve distribution area where at 10 min 60% of Ropiand 90% of Prilo patients had analgesia (P=0.017). At 10 min100 and 97% had motor block of the hand in the Ropi and Prilogroups, respectively. Recovery of the sensory block in all innervationareas was already observed 2 min after the tourniquet cuff release.At 10 min after releasing the tourniquet cuff 31% of the Ropipatients and none of the Prilo patients still had analgesiain the median nerve distribution (P=0.004). At 12 min, 42% inthe Ropi group and none in the Prilo group had decreased gripstrength. After the release of the tourniquet, mean plasma concentrationsof ropivacaine were higher than those of prilocaine. The highestindividual concentration of ropivacaine was 1.65 µg ml^–1and that of prilocaine 0.6 µg ml^–1. None of theRopi patients experienced any symptoms of local anaesthetictoxicity. Conclusions. Compared with prilocaine 5 mg ml^–1, analgesiain IVRA with ropivacaine 2 mg ml^–1 developed slightlymore slowly, while motor block developed at a similar rate.After the release of the tourniquet, sensation recovered quicklyand at a similar rate in the two groups, except for a slightlyslower recovery after ropivacaine in the innervation area ofthe median nerve, but no surgically useful extended analgesiaafter the cuff deflation was observed. Despite a 60% lower milligram-dose,ropivacaine plasma concentrations were markedly higher thanthose of prilocaine.     

Comparison of anesthetic effect between 0.375% ropivacaine versus 0.5% lidocaine in forearm intravenous regional anesthesia

BACKGROUND AND OBJECTIVES: Ropivacaine was shown to provide superior postblock analgesia to lidocaine in intravenous regional anesthesia (IVRA) in voluntary studies. The objective of this study was to compare the anesthesia efficacy, postblock analgesia, and local anesthetic-related side effects between ropivacaine and lidocaine when forearm IVRA was used. METHODS: Fifty-one patients undergoing outpatient hand surgery were randomized to receive forearm IVRA with either ropivacaine 0.375% or lidocaine 0.5%. The volume was 0.4 mL/kg up to 25 mL. Sensation to pinching by forceps and motor function was assessed at 5-minute intervals up to 15 minutes. After tourniquet deflation, verbal pain rating score (VRPS) at 15-minute intervals for the first 2 hours and time for first analgesic in the first 24 hours were evaluated. RESULTS: Eleven patients were excluded from the study with 20 patients remaining in each group. Onset time of anesthesia (6.5 +/- 2.9 minutes v 8.0 +/- 4.1 minutes for lidocaine and ropivacaine groups, respectively) and motor block were similar. In the postoperative period, VPRS was significantly lower in the ropivacaine group in the first 60 minutes (median, 0; P <.05) with significantly more patients in the ropivacaine group pain free (VPRS, 0) up to the first 90 minutes (P >.05). More patients in lidocaine group requested analgesic in the first 2 hours postblock, and only patients in the lidocaine group required supplemental IV morphine in the recovery room. Twenty-four hour analgesic consumption was the same. No local anesthetic-related side effects were observed. CONCLUSIONS: We conclude that 0.375% ropivacaine provides effective anesthesia and superior postoperative analgesia compared with 0.5% lidocaine when forearm IVRA is used.     

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.     

Intravenous regional analgesia with a forearm tourniquet

Lidocaine 0.5 per cent in a dose of 2 mg X kg-1 was used for intravenous regional analgesia with the tourniquet cuff placed over the forearm. The level of tourniquet cuff pressure employed was the arterial "occlusion pressure" plus 50 mmHg. In 48 normotensive patients successful analgesia was achieved; in seven hypertensive patients, four were pain-free, but the other three required more lidocaine to achieve adequate analgesia. No toxic symptoms and signs were observed. Measurement of serum lidocaine concentrations in 12 patients confirmed the safety of the technique, although small leakage of lidocaine past the inflated forearm tourniquet was detected in some patients.     

Local anaesthetic toxicity in a pregnant patient undergoing lignocaine-induced intravenous regional anaesthesia

A pregnant patient at 38 weeks' gestation developed symptoms of local anaesthetic toxicity following intravenous regional anaesthesia (IVRA) for hand surgery, using a standard dose of lignocaine. Reports suggest that a number of factors, both physiological and pharmacological, combine to increase the likelihood of local anaesthetic (LA) toxicity in pregnancy despite employment of a conventional "safe" IVRA technique. It is suggested that for IVRA, pregnant patients are premedicated with a benzodiazepine, the tourniquet time is increased and the concentration of LA is decreased to reduce the risks of LA toxicity.     

Locoregional intravenous anesthesia]

OBJECTIVE: To analyse current data on intravenous regional anaesthesia (IVRA), its benefits and drawbacks. DATA SOURCES: Articles were obtained from a Medline search using the following search terms: 'intravenous regional anaesthesia', alone or combined with 'local anaesthetic agents', 'toxicity'. STUDY SELECTION: Following articles in English and in French have been selected: main articles, original articles, update and review articles, letters to the editor and recent editorials. DATA EXTRACTION: Physiopathological and pharmacological data were extracted for involved mechanisms and means for improving this technique. DATA SYNTHESIS: IVRA is a reliable and efficient technique with a lower cost than general anaesthesia and well adapted for limb surgery in the ambulatory patient. Depending on the site of the surgical field, the pneumatic tourniquet is set either on the arm, forearm or wrist for the upper limb or thigh, calf or ankle for the lower limb. When set in periphery, less local anaesthetic agent is required. A wide tourniquet requires a lower inflation pressure than a double cuff tourniquet. A single cuff is as efficient as a dual cuff if shape, size and inflating pressure are appropriate. The limb occlusion pressure (LOP) is the minimal pressure required to occlude blood flow. It is assessed with either a pulse oximeter or Doppler for determination of the lowest cuff inflating pressure. The cuff is inflated to 50 mmHg above LOP. Oozing in the surgical field can be decreased by the re-exsanguination technique. Currently, lidocaine is the only local anaesthetic released in France for IVRA. Addition of a muscle relaxant, a NSAID or clonidine allows the dose of local anaesthetic agent to be decreased and improves postoperative analgesia.     

The analgesic effect of lornoxicam when added to lidocaine for intravenous regional anaesthesia

Background. The aim of the study was to evaluate the effectof lornoxicam (L) on sensory and motor block onset time, tourniquetpain, and postoperative analgesia, when added to lidocaine inintravenous regional anaesthesia (IVRA). Methods. Forty-five patients undergoing hand surgery were randomlyand blindly divided into three groups as to receive either i.v.saline and IVRA with lidocaine 0.5% (Control group, n=15), i.v.saline and IVRA lidocaine 0.5% with lornoxicam (L-IVRA group,n=15), or intravenous lornoxicam and IVRA lidocaine 0.5% (L-IVgroup, n=15). Sensory and motor blocks onset time, and tourniquetpain was measured after tourniquet application at 5, 10, 20,and 30 min, and analgesic use were recorded during operation.After the tourniquet deflation, at 1, 30 min, and 2, 4 h, visualanalogue scales score, the time to first analgesic requirement,total analgesic consumption in first 24 h, and side effectswere noted. Results. Sensory and motor block onset times were shorter andthe recovery time prolonged in the Group L-IVRA compared withthe other group (P=0.001). A decreased tourniquet pain, a prolongedtime first analgesic requirement [229 (85) min vs 28 (20) and95 (24) min, P=0.0038) and less postoperative analgesic requirementsduring 24 h were found in Group L-IVRA compared with the othergroups (P<0.05). Conclusions. The addition of lornoxicam to lidocaine for intravenousregional anaesthesia shortens the onset of sensory and motorblock, decreases tourniquet pain and improves postoperativeanalgesia without causing any side effect.     

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   

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.     

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.     

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.     

A modification of the inter-cuff technique of IVRA for use in knee arthroscopy

PURPOSE: To describe a modified approach to intravenous regional anesthesia (IVRA) for operations on the knee joint. CLINICAL FEATURES: A 52-yr-old male presenting for knee arthroscopy was anesthetized by IVRA using only 40 mL of lidocaine 0.5%. After performing IVRA in the routine way an additional below knee tourniquet was used and inflated after local anesthetic exsanguination towards the knee. Operation was performed without the need for further analgesic. CONCLUSION: The technique allowed the use of a small anesthetic volume for IVRA on the lower limb, thus decreasing the potential risk of local anesthetic toxicity.     

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.     

Intravenous regional anaesthesia

Intravenous regional anaesthesia (IVRA) was first described almost a century ago by August Bier and has been used for the past 50 years. It is a safe anaesthetic technique for upper or lower distal limb surgery. It utilizes a tourniquet, ideally a double tourniquet, followed by exsanguination of the appropriate limb after insertion of a cannula, through which local anaesthetic is injected. Anaesthesia and analgesia follow rapidly, the tourniquets preventing systemic local anaesthetic toxicity as well as fixing the local anaesthetic to where it is required. The safest local anaesthetic is prilocaine 0.5%. Lidocaine 0.5% can also be used. Several adjuvants have been described to prolong anaesthesia time and reduce tourniquet pain.     

Comparison of mepivacaine and lidocaine for intravenous regional anaesthesia: pharmacokinetic study and clinical correlation

Background. Limitations to the use of lidocaine for intravenousregional anaesthesia (IVRA) include lack of optimal intraoperativeanalgesia and systemic toxic reactions.This randomized double-blindstudy was conducted to compare intraoperative and postoperativeanalgesia, adverse effects, and plasma concentrations of mepivacaineor lidocaine, on release of the tourniquet in patients undergoingIVRA for distal upper limb surgery. Methods. Forty-two adult patients were randomly allocated toreceive either a 0.5% lidocaine solution 3 mg kg^–1 (n=20)or mepivacaine 5 mg kg^–1 (n=22). Plasma concentrationsof both anaesthetic agents were measured at 5, 10, 20, 30, 45,and 60 min after deflation of the tourniquet by gas chromatography. Results. Although plasma concentrations of mepivacaine and lidocainewere comparable 5 min after deflation, concentrations of lidocainedecreased significantly thereafter, whereas plasma concentrationsof mepivacaine were similar over the 60-min study period. Supplementaryanalgesia during the intraoperative period was required by 45%of patients in the lidocaine group as compared with 9% in themepivacaine group (P=0.02). No adverse effects were observedin patients given mepivacaine. In the lidocaine group, adverseeffects were observed in 10% of the patients. The total ischaemiatime, volume of the local anaesthetic, and duration of the surgicalprocedure were not significantly different between the two groups. Conclusions. Mepivacaine 5 mg kg^–1 ensured better intraoperativeanalgesia than lidocaine 3 mg kg^–1 when used for IVRA.Plasma concentrations of lidocaine decreased significantly between5 and 60 min following tourniquet deflation, whereas blood concentrationsof mepivacaine remained below the toxic concentration. Br J Anaesth 2002; 88: 516–19     

Lidocaine disposition following intravenous regional anesthesia with different tourniquet deflation technics

It has been claimed that tourniquet cycling, cyclic deflation and reinflation of the tourniquet at the termination of intravenous regional anesthesia (IVRA), enhances the safety of IVRA by minimizing the peak blood level of local anesthetics. To evaluate the validity of these claims and to determine the optimal cycling technic, peak arterial (Cmax) plasma concentrations of lidocaine were determined as well as the time to reach these peaks (Tmax) utilizing contralateral radial arterial blood samples in three groups of volunteers after 30 minutes of IVRA: In all three groups IVRA was induced with 3 mg/kg of lidocaine and maintained for 30 min. In the first group the tourniquet was then simply deflated once (and not reinflated); in the second group the tourniquet was deflated three times with variable periods of deflation (0, 10 and 30 seconds) separated by 1-minute periods of reinflation; and in the third group the tourniquet was again deflated 3 times but with fixed periods of deflation (10 sec) separated by 1 min periods of reinflation. The results obtained indicate that cycling technics do not appear to significantly reduce Cmax, but they do significantly prolong Tmax. Of the two cycling technics, the 10-second deflation interval technic appeared to be superior, both clinically and pharmacologically, as it was associated with less venous congestion and therefore less discomfort, and it sequentially decreased the arterial plasma concentration of lidocaine with each subsequent deflation-reinflation cycle.     

Adverse events associated with intravenous regional anesthesia (Bier block): a systematic review of complications

Study ObjectiveTo characterize the complications reported with intravenous regional anesthesia (IVRA).DesignLiterature search.SettingUniversity-affiliated hospital.MeasurementsA search was done in the American National Library of Medicine's PUBMED, EMBASE (1980-2007, wk 11), and Medline (from 1950) in March 2007. All complications associated with IVRA were reviewed.Main ResultsThe lowest dose of local anesthetic associated with a seizure was 1.4 mg/kg for lidocaine; 4 mg/kg for prilocaine, and 1.3 mg/kg for bupivacaine. Cardiac arrests and deaths were reported with lidocaine and bupivacaine only. The lowest dose associated with a cardiac arrest was 2.5 mg/kg for lidocaine and 1.6 mg/kg for bupivacaine. Local anesthetic toxicity occurring during tourniquet inflation has been reported, with tourniquet pressure exceeding initial systolic arterial blood pressure by 150 mmHg. Seizures occurring after tourniquet deflation have been reported with a tourniquet time as long as 60 minutes. Ten cases of compartment syndrome are reported.ConclusionSeizures have been reported with lidocaine at its lowest effective dose (1.5 mg/kg).     

Intravenous regional anesthesia using lidocaine and neostigmine for upper limb surgery

Study ObjectiveTo evaluate the effect of adding neostigmine to lidocaine in intravenous regional anesthesia (IVRA).DesignRandomized, double-blinded study.SettingTertiary-care academic medical institution.Patients40 ASA physical status I and II patients scheduled for elective or emergency forearm and hand surgery.InterventionPatients were randomized to two groups of 20 patients each. In the control group, IVRA was established using 40 mL of 0.5% lidocaine with one mL of isotonic saline, while neostigmine group patients received 40 mL of 0.5% lidocaine with 0.5 mg neostigmine.MeasurementsHemodynamic parameters, onset and recovery times of sensory and motor blocks, and quality of anesthesia achieved with IVRA were recorded. After tourniquet deflation, visual analog pain scores (VAS) were noted every 30 minutes in the first two hours, as were the time to first analgesic request and total analgesic requirement in the 24-hour postoperative period.Main ResultsIn the first 24 hours after surgery, the neostigmine group had significantly lower VAS scores, longer time to first analgesic request, and reduced total analgesic requirement. Intraoperatively, the neostigmine group had significantly shorter sensory and motor block onset times and longer recovery times than the control group. No significant frequency of adverse effects was seen in either group. The quality of intraoperative anesthesia and frequency of tourniquet pain were similar in both groups.ConclusionsThe addition of neostigmine to lidocaine shortens onset time and improves postoperative analgesia in IVRA for upper limb surgery.