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An unusual case of mepivacaine toxicity with ventricular tachycardia in a newborn infant is presented. The mepivacaine probably reached the infant by direct injection into the scalp. Effective removal of the drug by gastric lavage was demonstrated. Exchange transfusion may also have been instrumental in the infant's survival by reducing the high blood concentration of mepivacaine.
OBJECTIVES: To assess the duration of both sensory and motor blockade of brachial plexus with 40 mL 1% mepivacaine after axillary or midhumeral approach. STUDY DESIGN: Prospective, open, non-comparative, multicentric study. PATIENTS: One hundred and eighty patients, ASA physical class 1 and 2, scheduled for hand or forearm surgery under brachial plexus block were included. METHODS: A midhumeral or axillary brachial plexus block using a nerve stimulator was performed with 40 mL of 1% mepivacaine. Sensory blockade was tested for each cutaneous area (median, radial, ulnar, musculocutaneous and medial cutaneous nerve of the forearm) using pin-prick. Motor blockade was assessed by grip strength of the hand. Incidence and duration of analgesia, anaesthesia and motor blockade were assessed. The incidence of tourniquet pain and the time when pain occurred were determined. RESULTS: According to the nerve area tested, analgesia and anaesthesia were obtained in 98% and 85% of cases respectively; duration of anaesthesia was between 150 +/- 40 to 167 +/- 49 minutes and duration of analgesia was from 184 +/- 50 to 205 +/- 51 minutes. Duration of paralysis was 144 +/- 40 minutes and duration of paresis was 190 +/- 51 minutes. Pain occurred in three out of 138 patients at tourniquet inflation and in six patients after completion of surgery. CONCLUSIONS: Mid humeral or axillary block with 40 mL of 1% mepivacaine is highly successful and provides efficient surgical anaesthesia for various surgical procedures of intermediary duration.
OBJECTIVES: To evaluate the distribution of sensory blockade, the onset time and the duration of the axillary plexus block obtained after the administration of 40 mL of 1.5% lignocaine with adrenaline or 40 mL of plain 1.5% mepivacaine. STUDY DESIGN: Prospective, randomised, comparative, double blind study. PATIENTS AND METHODS: One hundred and fifty five patients undergoing hand surgery were randomised into two groups: in group L, 73 patients were given 1.5% lignocaine with 1/200,000 adrenaline and in group M, 82 patients received 1.5% mepivacaine. The entire volume was injected on the first evoked motor activity obtained for a current less than 0.5 mA. Sensory and motor block of each of the four major nerves of the hand and forearm were assessed using light touch and motor strength respectively. The block was considered complete when all nerves were anaesthetised (median, radial, musculocutaneous and ulnar). RESULTS: The percentage of complete sensitive blockade was 22% in group L and 24% in group M. Complete motor blockade was respectively 27% in group L and 40% in group M. The median time required to obtain a complete sensory blockade was 18 min for both group. The median time required to obtain a complete motor blockade was 17 min in-group L and 16 min in-group M. The duration of the sensory blockade was not different for both groups (i.e., 255 +/- 76 min versus 231 +/- 70 min in group L and M respectively. The duration of the motor blockade was longer in group L compared to group M (199 +/- 64 min versus 231 +/- 74 min respectively, p < 0.05). CONCLUSION: Following axillary plexus block, 1.5% mepivacaine improves neither the extension nor the duration of sensory blockade achieved by 1.5% lignocaine with adrenaline.
BACKGROUND: The purpose of this study was to compare anesthetic efficacy and postoperative analgesia of 0.5% ropivacaine and 1% mepivacaine for sciatic nerve block in the popliteal fossa (popliteal block). METHODS: A prospective, double-blind study was carried out in 58 adult patients scheduled for outpatient foot or ankle surgery. They were randomized to receive popliteal block with 40 ml of either 0.5% ropivacaine (group R) or 1% mepivacaine (group M). An atraumatic, Teflon-coated needle connected to a neurostimulator was used to make a single puncture using a posterior approach. The times to onset of sensory and motor block, and the need for intraoperative sedation were recorded. Before discharge, patients were asked to document the time to first analgesic use, time to return of full sensation in the foot, and their evaluation of the technique. RESULTS: Onset time (mean+/-standard deviation, 95% confidence interval) of both sensory block (6.5+/-5.1 min, 4.47-8.49, in group R and 6.2+/-3.7 min, 4.83-7.69, in group M) and motor block (6.6+/-4.4 min, 4.81-8.23, in group R and 7.9+/-4.1 min, 6.29-9.53, in group M) was similar in both groups. Postoperative analgesia lasted longer in group R (15.2+/-5.1 h, 13.25-17.21) than in group M (5.7+/-1.8 h, 5.01-6.41; P<0.001). Duration of sensory block was longer in group R (20.7+/-6.2 h, 18.51-23.01) than in group M (6.5+/-1.7 h, 5.86-7.16; P<0.001). Acceptance of the anesthetic procedure was similar in both groups. CONCLUSION: In this study we demonstrated that both 0.5% ropivacaine and 1% mepivacaine for popliteal block produced rapid, effective and safe anesthesia but postoperative analgesia was more long-lasting with ropivacaine.
BACKGROUND AND OBJECTIVES: Ropivacaine 1% has recently been used in clinical trials for peribulbar anesthesia. This study aims to compare the safety and the efficacy of ropivacaine 0.75% with that of a 1:1 mixture of bupivacaine 0.5% and mepivacaine 2% for peribulbar anesthesia. METHODS: Two thousand patients undergoing peribulbar anesthesia for elective cataract phacoemulsification were prospectively studied over a 1-year period and randomly assigned to 1 of 2 groups according to the local anesthetic used. One thousand patients were administered peribulbar anesthesia with 9 mL of ropivacaine 0.75% plus 1 mL of hyaluronidase (group R), and 1,000 patients received peribulbar anesthesia with 4 mL of bupivacaine 0.5% plus 4 mL of mepivacaine 2% plus 1 mL of hyaluronidase plus 1 mL of sodium bicarbonate (group BM). Peribulbar anesthesia was always accomplished by the same physician by 2 injections of 5 mL each, with a 25-gauge 25-mm needle. Evaluation was performed by another physician blinded to the technique used and included assessment of pain on local anesthetic injection, ocular and eyelid akinesia, need for top-up injections, onset time and duration of anesthesia, intraoperative analgesia, duration of surgery, hemodynamic parameters, and incidence of perioperative complications. RESULTS: A greater incidence of pain on injection was found in group BM (P<.001). No difference between the groups was found regarding the onset time and the duration of anesthesia. Perioperative analgesia was satisfactory in both groups with no significant difference. Patients in group R showed a reduced need for top-up injection and a better ocular akinesia at 8 and 10 minutes (P<.01). The akinesia of the eyelid was comparable in the 2 groups and complete in all cases at 8 minutes. Cardiac arrhythmias were more frequent in group BM (P<.01). Local complications did not differ between the groups. An increase in mean artierial blood pressure and heart rate was observed in both groups 1 minute after injection of local anesthetic. CONCLUSIONS: Peribulbar anesthesia with ropivacaine provided better ocular akinesia 8 to 10 minutes after block insertion than a bupivacaine-mepivacaine mixture, which reduced the need for top-up injections. Ropivacaine also caused less pain on injection.
BACKGROUND: Retro- or peribulbar anaesthesia are the standard procedures for cyclodestructive surgery. Because these methods of anaesthesia may further compromise optic nerve function, especially in advanced glaucoma, subconjunctival anaesthesia was evaluated as an alternative procedure in cyclocryotherapy. PATIENTS AND METHODS: 1. To evaluate the current methods of anaesthesia a questionnaire was sent to all University Eye Clinics in Germany in 2001. 2. A prospective, consecutive study concerning cyclocryotherapy in advanced glaucoma was started using subconjunctival anaesthesia with 5 % cocaine or, alternatively, 2 % mepivacaine in 25 eyes of 25 patients in each group. Pain during cyclocryotherapy was recorded using a 10-point rating-scale (1 = no pain to 10 = intolerably severe pain) and adverse events were also recorded. RESULTS: 1. 88.6 % of the University Eye Clinics in Germany replied to our questionnaire. In 2001 cyclocryotherapy was performed in 80.6 % of the University Eye Clinics in Germany (Tübingen not included), 16.1 % among them solely used cyclocryotherapy for the treatment of advanced glaucoma. 2. Using 5 % cocaine for subconjunctival anaesthesia - 92 % of patients experienced no pain and 8 % of patients reported very mild pain during cyclocryotherapy. One patient reported nausea, 4 patients mouth dryness. After anaesthesia with mepivacaine - 80 % experienced no pain, 12 % very mild pain, and 8 % mild pain. There were no systemic side effects. CONCLUSION: Most of the patients experienced no pain during cyclocryotherapy using subconjunctival anaesthesia with cocaine or mepivacaine. Therefore, risks and side effects of retro- or parabulbar anaesthesia can be successfully avoided by this simple modification.
To evaluate the subjective and objective response to intravenous regional administration of a glucocorticoid (IVRAG) on rheumatoid arthritis (RA), twenty RA-patients received, in a randomised, double-blind crossover and placebo-controlled fashion, either 50 mg methylprednisolone in mepivacaine 0.25% or mepivacaine (placebo) in one hand only using a Bier-block technique. The other hand was given the opposite. One week later the procedure was repeated but the previous placebo hand was now treated with the glucocorticoid. About 50% of the patients experienced a subjective improvement at 1 and 6 weeks. After one week a significant reduction was recorded in grip diastasis with no difference between the glucocorticoid and the placebo. In the other outcome measures (grip strength, handvolume, rest pain, and movement provoked pain) no differences were recorded between the glucocorticoid and placebo. At six weeks a significant reduction in grip diastasis and movement provoked pain as well as a significant increase in grip strength were noted. Hand volume was unchanged. IVRAG is a safe, easy and well-tolerated technique. The beneficial results are probably due to both a systemic and a regional effect. The findings of benefit in both hands at the end of one week seem to suggest that mepivacaine can give some short term improvement.
The duration of action and vascular effects of L(+) and D(-) and racemic mepivacaine were investigated in a double-blind study in 23 fit volunteers. Isosmolar 0.1-ml intradermal injections of a range of concentrations of each agent from 0.011% to 2.7%, and physiological saline were given in duplicate to at least 14 subjects. Local colour changes were observed 5-10 min after injection, and analgesia to pinprick was tested at 5-min intervals thereafter until full recovery. Both isomers were vasoconstrictor at concentrations of 0.3% and less; at greater concentration the L isomer produced more vasodilation and haemorrhagic change. The duration of action of both isomers increased with concentration between 0.05 and 0.9%, but the L isomer was significantly longer acting than the D at 0.3% and more. The log dose-duration curve could be interpreted as linear between 0.1 and 0.9% with the slope of L isomer being twice as steep as the D. The findings for racemic mepivacaine were between those of the two isomers. The longer duration of analgesia of L-mepivacaine was not associated with superior vasoconstrictor power.
Mepivacaine and bupivacaine are used clinically as racemic mixtures of enantiomers. In these studies the enantiomers of each agent were administered separately to sheep by i.v. bolus injection on separate occasions. Enantioselective disposition was deemed if the R:S ratio of the relevant pharmacokinetic parameter differed significantly from unity. Both enantiomers of both agents were cleared principally by the liver; urinary excretion of unmetabolized agents accounted for less than 2% of the doses. For R(-)-and S(+)-mepivacaine, respective mean (SEM) values of parameters were: total body clearance 1.20 (0.29) litre min-1 and 0.97 (0.20) litre min-1 (ns); total volume of distribution 144 (39) litre and 80 (21) litre (P less than 0.05); slow half-life 120 (40) min and 84 (22) min (ns); mean hepatic extraction ratio 0.50 (0.14) and 0.52 (0.09) (ns); mean hepatic clearance 0.75 (0.23) litre min-1 and 0.75 (0.18) litre min-1 (ns). For R(+)- and S(-)-bupivacaine, respective values were: total body clearance 0.77 (0.33) litre min-1 and 0.53 (0.26) litre min-1 (P less than 0.05); total volume of distribution 40 (10) litre and 43 (10) litre (ns); slow half-life 57 (10) min and 104 (21) min (P less than 0.05); mean hepatic extraction ratio 0.46 (0.15) and 0.29 (0.13) (P less than 0.05); mean hepatic clearance 0.85 (0.31) litre min-1 and 0.54 (0.26) litre min-1 (P less than 0.05). Thus there was enantioselective distribution of mepivacaine and enantioselective clearance of bupivacaine, but the magnitude of the effect was relatively small.
BACKGROUND: The multiple injection technique for axillary block, in which the four distal nerves of the plexus are located by a nerve stimulator and separately injected, has been shown to provide a high success rate and a short onset time. This randomized double-blind study was conducted to compare the effectiveness of three different volumes of mepivacaine 10 mg x ml(-1) in patients undergoing elective distal upper limb surgery under axillary brachial plexus block with the four-nerve approach. The number of complete sensory blocks was the primary efficacy variable. METHODS: A total of 114 adult patients were randomly allocated to receive 36 (n=38), 28 (n=38), and 20 ml (n=38) of mepivacaine 10 mg x ml(-1). In each group, volumes were equally distributed in the four nerve territories. In all patients, performance time, latency time, block characteristics, need of supplementary blocks, tourniquet tolerance, duration of analgesia, and complications were recorded. RESULTS: Complete sensory block was obtained in 97% of patients receiving a volume of 36 ml, 97% of those receiving 28 ml, and 94% of those receiving 20 ml. One patient in the group of 28 ml and five patients in the group of 20 ml experienced pain on inflation of the tourniquet. Two months after surgery, no case of postoperative neurological dysfunction was observed. CONCLUSIONS: The three volumes (38, 28, and 20 ml) of mepivacaine 10 mg x ml(-1) ensured a similar and high percentage of complete sensory blocks in axillary brachial plexus anaesthesia with nerve stimulation involving the location of four motor responses.
UNLABELLED: To date, results of studies evaluating the efficacy of opioids and local anesthetic combinations in the brachial plexus are inconclusive. We examined whether increasing sufentanil in doses of 5, 10, and 20 microg decreased onset time or increased duration of an axillary brachial plexus block. Ninety-two patients scheduled for carpal tunnel release under axillary brachial plexus block were enrolled in the study. Patients were randomized to receive axillary plexus block with 40 mL 1.5% mepivacaine and saline (Group 1), sufentanil 5 microg (Group 2), 10 microg (Group 3), or 20 microg (Group 4). Onset and duration of sensory and motor block were measured. Opioid-related side effects were recorded. The addition of sufentanil did not improve speed of onset or increase the duration of sensory or motor block. Paradoxically, duration of sensory and motor block was longest in the control group: sensory, 241 min (188-284) and motor, 234 min (128-305), and decreased with increasing doses of sufentanil in Group 4: sensory, 216 min (115-315) and motor, 172 min (115-260) (P < 0.05). Side effects occurred in 55% of patients belonging to Groups 2 and 4, and in 60% of the patients in Group 3. In contrast, only 10% of the patients reported side effects in the control group. We conclude that sufentanil added to mepivacaine does not increase the onset or prolong the duration of an axillary plexus block. Furthermore, the addition of sufentanil was associated with a frequent incidence of side effects. IMPLICATIONS: This study demonstrates that the addition of sufentanil in a dose-dependent manner to 1.5% mepivacaine in the axillary plexus does not improve onset or duration of blockade, and that this admixture is associated with an increased incidence of side effects.
Perivascular axillary blockade was performed on 90 patients with the aid of a catheter technique. The patients were randomly allocated to receive either 40, 50 or 60 ml of 1% mepivacaine with adrenaline 1:200,000. Blood concentrations of mepivacaine were measured up to 90 min after injection in seven, eight and ten of the patients from the three groups. Sensory and motor blockade was evaluated 20, 30 and 40 min after injection. All groups showed the same temporal development of the blockade, i.e. improval of the blockade during the period from 20 to 40 min after injection, but no difference was found in the sensory or motor blockade between the three groups. However, a further analysis of the incomplete blockades showed a better quality of the sensory blockade in the groups given 50 and 60 ml than in the group given 40 ml. None of the 90 patients showed any signs of systemic toxic reactions. The mean peak values of blood concentrations were 0.5-1.0 microgram/ml higher in the groups given 50 ml and 60 ml than in the group given 40 ml. On the basis of the present and two previous investigations on the dose response in perivascular axillary blockade, a dose of 50 ml 1% mepivacaine with adrenaline or another equivalent drug with vasoconstrictor is recommended.
Perivascular axillary blockade was performed on 60 patients with the aid of a catheter technique. The patients were randomly allocated to two groups. All patients received the same dose of local anaesthetic: 60 ml of mepivacaine 1% with adrenaline, but one group received the dose as a bolus injection, whereas the other group received the dose as fractional injections of 30 + 30 ml with an interval of 20 min. Blood concentrations of mepivacaine were measured up to 90 min after injection of local anaesthetic. Sensory and motor blockade were evaluated 20, 30 and 40 min after injection. Forty minutes after the last injection of local anaesthetic, there was no difference between the blockades of the two groups, except for the sensory blockade of the lower lateral cutaneous nerve of the arm, in which the frequency of analgesia was 90% after bolus injection and 63% after fractional injections. There was no difference in blood concentrations of mepivacaine between the two groups. None of the 60 patients showed any sign of systemic toxic reactions. Fractional injection of local anaesthetic in perivascular axillary blockade does not offer any advantage over bolus injection with regard to the resulting blockade.
The extent of sympathetic blockade in 36 patients, who had been given extradural analgesia, was studied by means of the skin conductance response (SCR). The SCR was also studied in six healthy volunteers who received, in a cross-over fashion, infusions of physiological saline (placebo) and saline containing mepivacaine. Two more volunteers were given saline containing bupivacaine. Extradural analgesia caused a partial blockade of sympathetic activity. The higher the level of analgesia the greater the degree of inhibition of the SCR. Complete blockade of the SCR or only a weak response in the foot was obtained in the majority of cases when the level of analgesia reached a dermatome level of T4 or higher. There was no significant relationship between the degree of motor blockade of the lower extremities and the intensity of blockade of the SCR. Extradural injection of 2% mepivacaine had a greater effect on the SCR than did 0.5% bupivacaine. There was no indication that infusion of mepivacaine or bupivacaine in volunteers, whose blood levels were as high as or higher than those likely to be produced during extradural analgesia, affected the SCR.
In a double-blind study young volunteers randomly received 20 ml of mepivacaine 2%, bupivacaine 0.5% or etidocaine 1.5% epidurally, all solutions with adrenaline. The mean cephalad spread of pin-prick analgesia was equal (T10) in the groups, but the duration was longest for bupivacaine and etidocaine. The motor blockade of the rectus abdominis muscles was assessed quantitatively by rectified integrated electromyographic recordings (RIEMG) and as number of turns in EMG recordings [changes in the direction (rise/fall) of the EMG; TURNS] from three different segmental levels, T7, T9 and T11. The motor blockade of the quadriceps muscles was estimated by EMG recordings simultaneously with muscle force measurements at maximal isometric knee extension. Motor blockade was also evaluated by the Bromage scale. There was good correlation (correlation coefficient 0.91) between RIEMG values and muscle force in knee extension during epidural anaesthesia. TURNS showed a non-linear relationship to isometric force during epidural anaesthesia and added no further information. At the lower parts of the abdomen (T11), etidocaine gave more profound and longer motor blockade than mepivacaine. For quadriceps muscle function, motor blockade was almost complete with all three local anaesthetics; the duration of maximum motor blockade was short (45-60 min) for mepivacaine, but about 5 h with etidocaine. At the time when the Bromage scale indicated complete regression of motor blockade, the muscle force of knee extension was only 30% and the quadriceps RIEMG 35% of control values and 1-3 h remained until the time of mobilization.(ABSTRACT TRUNCATED AT 250 WORDS)
The pulmonary first-pass kinetics of the amide-linked local anaesthetics prilocaine, mepivacaine and bupivacaine were studied in 33 patients after a single epidural injection. Drug concentrations were monitored before and after lung passage, i.e. in samples withdrawn simultaneously from mixed venous and arterial blood. In most cases, maximum plasma concentrations were observed 10 min after injection (range 2 to 30 min). Two min after injection the local anaesthetics were distinctly extracted by the lung (prilocaine 40%, mepivacaine 20%, and bupivacaine 12%). Prilocaine was retained by the lung more effectively than bupivacaine and mepivacaine. However, a transpulmonary concentration gradient could be observed only for a short time, i.e. maximum 15 min. Altogether, in the case of accidental fast absorption, e.g. inadvertent intravenous injection, arterial peak concentrations of these drugs will be attenuated by passage of the lung. However, the lung will not substantially lower the risk of toxicity by amide-linked local anaesthetics during normal conditions of regional anaesthesia where slow absorption occurs.
BACKGROUND: Transient radicular irritation (TRI) is common after spinal anesthesia induced with hyperbaric lidocaine 50 mg/ml. The purpose of this study was to determine the incidence of TRI after spinal anesthesia with hyperbaric lidocaine 50 mg/ml diluted with cerebrospinal fluid (CSF) 1:1 and hyperbaric mepivacaine 40 mg/ml and hyperbaric bupivacaine 5 mg/ml. METHODS: Ninety ASA class I-IV patients undergoing mostly brief urological procedures under spinal anesthesia were randomly allocated to receive either hyperbaric lidocaine 50 mg/ml diluted with CSF 1:1 (Group L), hyperbaric mepivacaine 40 mg/ml (Group M) or hyperbaric bupivacaine 5 mg/ml (Group B). Characteristics of the patients and details of the surgical procedures and spinal anesthesias were similar in all groups except for the intensity of motor block. The patients were evaluated on the first postoperative day by an anesthesiologist who did not know which spinal anesthetic agent had been used. RESULTS: Six patients (20%) in group L, 11 patients (37%) in Group M and none (0%) in Group B experienced pain in the legs and/or back (TRI) after spinal anesthesia. CONCLUSION: TRI is frequent after spinal anesthesia induced with hyperbaric lidocaine 50 mg/ml diluted with CSF 1:1. The incidence of TRI after hyperbaric mepivacaine 40 mg/ml is of the same magnitude. TRI could not be observed after bupivacaine spinal anesthesia.
AIM: To assess the efficacy and safety of an intraoperative intracameral injection of mepivacaine, administered when patients experienced pain during the course of cataract surgery under topical anaesthesia. METHODS: This is a prospective placebo controlled double masked randomised clinical trial. 50 eyes were included; 25 receiving the active compound and 25 receiving placebo. Mepivacaine (2%, 0.4 ml) or placebo was administered intraoperatively under the iris of the patients who experienced pain during the course of phacoemulsification in spite of previous topical anaesthesia. Efficacy was evaluated by the patients themselves using a five point subjective pain rating scale, the Keele verbal pain chart. Safety was measured by assessing intraocular inflammation (clinical evaluation and laser flare meter), intraocular pressure, and endothelial cell count. RESULTS: The pain rating score significantly diminished after intracameral injection in the mepivacaine group (mean 3.0 (95% CI 2.6-3.4) v 0.8 (0.3-1.3), p<10(-4))) while remaining unchanged in the placebo group (2.9 (2.6-3.2) v 2.9 (2.5-3. 3)), the mean reduction in pain score being significantly different between the two groups (p<10(-4)). There was no indication of increased postoperative ocular inflammation, intraocular pressure change, or endothelial cell loss. CONCLUSIONS: These results suggest that it may not be necessary to systematically add intracameral anaesthesia with topical anaesthesia for cataract surgery. An intraoperative intracameral injection, performed only in patients who happen to suffer during surgery, is safe and effective.