Epinephrine does not reduce the plasma concentration of lidocaine during continuous epidural infusion in children

PURPOSE: During continuous epidural anesthesia with lidocaine, plasma monoethylglycinexylidide (MEGX), an active metabolite of lidocaine, increases continuously. We assessed the effect of epinephrine on the absorption of lidocaine and the accumulation of MEGX during continuous epidural anesthesia in children. METHODS: Anesthesia was administered as an initial bolus of 5 mg x kg(-1) of 1% lidocaine solution followed by continuous infusion at 2.5 mg x kg(-1) x hr(-1). Patients in the control group (n = 8) received lidocaine alone, while patients in the epinephrine group (n = 8) received lidocaine + epinephrine (5 microg x mL(-1)). Concentrations of lidocaine and its active metabolite, MEGX, were measured in plasma samples obtained after 15 min, 30 min, and one, two, three, four, and five hours of infusion using high-performance liquid chromatography with ultraviolet detection. RESULTS: Plasma lidocaine concentrations were higher in samples from the control group for the first hour; however, after two hours the levels were the same in all samples. Plasma MEGX levels increased continuously in both groups and were significantly higher in the control group samples. The sum of lidocaine + MEGX was higher in the control group for the first two hours but there was no significant difference between groups after three hours. CONCLUSIONS: Reduction of the potential for systemic toxicity by the addition of epinephrine to lidocaine is limited, because the reduction of the sum of the plasma concentrations of lidocaine and its active metabolite MEGX is small and limited to the initial phase of infusion.     

Plasma lidocaine, monoethylglycinexylidide, and glycinexylidide concentrations after epidural administration in geriatric patients

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate the effect of age on the pharmacokinetics of lidocaine after epidural administration. METHODS: Two percent lidocaine with epinephrine (5 microg/mL) was administered in two different age groups: an adult group (age 42 +/- 6 years, n = 10) and an elderly group (age 77 +/- 4 years, n = 10). Concentrations of lidocaine and its active metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), were measured in plasma samples obtained after 15, 30, 45, 60, 90, 120, 150, and 180 minutes of administration using high-performance liquid chromatography with ultraviolet detection. RESULTS: No significant differences in plasma concentrations of lidocaine and its metabolites were observed between the two groups during the 3 hours of study. However, the elderly group showed significantly longer mean residence times (MRTs) and lower plasma clearance of lidocaine during the period compared with the adult group (P < .05). Plasma concentration ratios of MEGX/lidocaine were significantly lower in the elderly group after 2 hours of lidocaine administration (P < .05). CONCLUSIONS: The increase in plasma lidocaine concentration after epidural anesthesia in elderly patients was not as high as anticipated. However, the elderly patients showed longer MRTs, lower clearance, and lower ratios of MEGX/lidocaine than did the adult (middle-age) patients.     

Free lidocaine concentrations during continuous epidural anesthesia in geriatric patients

BACKGROUND AND OBJECTIVES: To evaluate the effects of aging on lidocaine pharmacokinetics, the plasma concentrations of total and free lidocaine and its metabolites were measured during continuous thoracic epidural anesthesia in middle-aged (age 41 +/- 9 years, n = 7) and elderly (age 72 +/- 2 years, n = 7) male patients. METHODS: After establishment of general anesthesia, 7 mL 1.5% lidocaine with epinephrine 1:200,000 was injected into the epidural space and subsequently infused at a rate of 5 mL/h for 5 hours. Plasma concentrations of total and free lidocaine, monoethylglycinexylidide (MEGX), and glycinexylidide (GX) were measured at 10, 15, 20, 30, 45, 60, 90, 120, 150, 180, 240, and 300 minutes after initial lidocaine injection using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. RESULTS: The elderly group showed a stronger upward trend in the corrected free lidocaine concentrations and lower corrected total MEGX concentrations than the middle-aged group. CONCLUSIONS: Lidocaine metabolite activity in the elderly male patients was lower than that in the middle-aged male patients. Free lidocaine concentration is prone to increase in elderly patients. Caution must be exercised during continuous thoracic epidural anesthesia combined with general anesthesia in geriatric patients.     

Propofol does not inhibit lidocaine metabolism during epidural anesthesia

Propofol is sometimes used in combination with epidural anesthesia with lidocaine. In this study, we investigated the effect of propofol on the plasma concentration of lidocaine and its principal metabolites during epidural anesthesia with lidocaine. Thirty-two patients were randomly allocated to receive either propofol or sevoflurane anesthesia (n = 16 each). In the propofol group, anesthesia was maintained with a target concentration of propofol of 4 microg/mL. In the sevoflurane group, anesthesia was maintained with 1.5% sevoflurane. Lidocaine was administered epidurally in an initial dose of 5 mg/kg, followed by a continuous infusion at 2.5 mg x kg(-1) x h(-1). Free components of plasma lidocaine and its metabolites-monoethylglycinexylidide (MEGX) and glycinexylidide (GX)-were measured 30, 60, 120, and 180 min after the initiation of continuous epidural injection by using high-performance liquid chromatography. Free lidocaine, MEGX, and GX were separated from 2 mL of plasma by ultrafiltration filter units. Hemodynamic data were similar between groups. The plasma concentrations of free lidocaine were not significantly different between groups. The ratios of free MEGX to free lidocaine and free GX to free MEGX were not different between groups. In conclusion, propofol does not alter the metabolism of epidural lidocaine compared with sevoflurane.     

Plasma lidocaine concentrations during continuous epidural infusion of lidocaine with and without epinephrine

Plasma lidocaine concentrations were measured over a five-hour period in 20 patients following continuous epidural infusion of lidocaine for surgical anaesthesia. Patients were divided into two groups: Group I received plain lidocaine; Group II received lidocaine with epinephrine. Patients initially received 10 ml followed by a constant infusion of 10 ml.hr-1 of two per cent lidocaine. The mean plasma concentrations of lidocaine were significantly higher for the first 40 min in Group I than in Group II. However, from one to five hours, there was no significant difference between the groups. These results demonstrate that the addition of epinephrine to lidocaine does not decrease the plasma concentration of lidocaine during continuous epidural infusion for long operations.     

Plasma concentrations of lidocaine and its principal metabolites during intermittent epidural anesthesia

Plasma concentration-time courses of lidocaine and its principal metabolites (monoethylglycinexylidide, MEGX, and glycinexylidide, GX) were studied during intermittent epidural injections of lidocaine HCl in eight female patients (ASA status 1). The initial dose (320-400 mg without epinephrine) followed by top-up injections of about 60% of the mean initial dose every 35-55 min resulted in a plasma accumulation of lidocaine: the peak concentration increased from 2.30 +/- 0.46 (mean +/- SD) microgram/ml following the first injection and 3.34 +/- 0.76 microgram/ml after the second, to 4.11 +/- 0.72 microgram/ml following the third. The maximum concentrations of MEGX and GX were 0.66 +/- 0.22 and 0.28 +/- 0.08 microgram/ml, respectively. A pharmacokinetic model could successfully fit the entire plasma concentration-time profile of lidocaine during repeated epidural injections (r2 = 0.886 to 0.983). Such pharmacokinetic variables as elimination half-life (t1/2, 2.33 +/- 0.43 h), apparent volume of distribution divided by bioavailability (Vd/F, 2.51 +/- 0.61 l/kg), and clearance divided by bioavailability (Cl/F, 11.65 +/- 1.21 ml X kg-1 X min-1) obtained from the female patients were in reasonable agreement with those reported from healthy females receiving the intravenous lidocaine HCl. A computer-aided simulation generated from using the mean kinetic data in a 50-kg woman predicted that plasma lidocaine concentration would reach the postulated toxic range (approximately equal to 6 microgram/ml) after the fourth supplementary dose under a similar dosing scheme as performed in this study. In conclusion, an accumulation of lidocaine in plasma occurs during a usual intermittent epidural dosing.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma lidocaine concentrations during continuous thoracic epidural anesthesia after clonidine premedication in children.

There is no report concerning oral clonidine's effects on epidural lidocaine in children. Therefore, we performed a study to assess the concentrations of plasma lidocaine and its major metabolite (monoethylglycinexylidide [MEGX]) in children receiving continuous thoracic epidural anesthesia after oral clonidine premedication. Ten pediatric patients, aged 1-9 yr, were randomly allocated to the Control or Clonidine 4 microg/kg group (n = 5 each). Anesthesia was induced and maintained with sevoflurane in oxygen and air (FIO2 40%). Epidural puncture and tubing were carefully performed at the Th11-12 intervertebral space. An initial dose of 1% lidocaine (5 mg/kg) was injected through a catheter into the epidural space, followed by 2.5 mg x kg(-1) x h(-1). Plasma concentrations of lidocaine and MEGX were measured at 15 min, 30 min, and every 60 min for 4 h after the initiation of continuous epidural injection. The concentrations of lidocaine and MEGX were measured using high-pressure liquid chromatography with ultraviolet detection. Hemodynamic variables were similar between members of the Control and Clonidine groups during anesthesia. The Clonidine group showed significantly smaller lidocaine concentrations (p < 0.05) and the concentration of MEGX tended to be smaller in the plasma of the Clonidine group for the initial 4 h after the initiation of epidural infusion. In conclusion, oral clonidine preanesthetic medication at a dose of 4 microg/kg decreases plasma lidocaine concentration in children. IMPLICATIONS: Oral clonidine decreases the plasma lidocaine concentration in children. Our finding may have clinical implications in patients receiving continuous epidural anesthesia. Additionally, perhaps an additional margin of safety regarding lidocaine toxicity is gained through the use of oral clonidine in children who will receive epidural lidocaine.     

The addition of epinephrine increases intensity of sensory block during epidural anesthesia with lidocaine

BACKGROUND AND OBJECTIVES: Little is known about the effect of adding epinephrine to local anesthetic solutions on the intensity of sensory block during epidural anesthesia. This study examined development of sensory block during lumbar epidural anesthesia using a cutaneous current perception threshold (CPT) quantitative sensory testing device. METHODS: Twenty ASA I patients who were randomly divided to receive 10 mL 1% lidocaine with (group E) or without (group P) epinephrine 1:200,000. Current perception threshold at 2,000, 250, and 5 Hz stimulation at the trigeminal (V), ninth thoracic (T9), and second lumbar (L2) dermatomes, and the dermatomal levels of block of light touch, temperature, and pinprick discrimination were measured before and every 5 minutes, until 60 minutes after injection of epidural lidocaine. RESULTS: After epidural administration of lidocaine with epinephrine, all CPT significantly increased at T9 and L2, whereas no increase was detected after epidural plain lidocaine. Areas under the curves, calculated to express overall magnitude and duration of CPT values, were significantly larger in group E than those in group P at 2,000 and 250 Hz at T9. No differences were observed in the maximal levels of loss of cold, pinprick, and touch sensations between both groups. CONCLUSIONS: These results suggest that lumbar epidural anesthesia using 10 mL 1% lidocaine with epinephrine produces a more intense block of both large and small diameter sensory nerve fibers than that with plain lidocaine. It appears, therefore, that the addition of epinephrine improves the quality of sensory block during epidural anesthesia with lidocaine.     

Small-dose dopamine increases epidural lidocaine requirements during peripheral vascular surgery in elderly patients

We studied 20 patients over the age of 65 yr undergoing prolonged peripheral vascular surgery under continuous lidocaine epidural anesthesia, anticipating that the increased hepatic metabolism caused by small-dose IV dopamine would lower plasma lidocaine concentrations. Subjects were assigned (random, double-blinded) to receive either a placebo IV infusion or dopamine, 2 microg. kg(-1). min(-1) during and for 5 h after surgery. Five minutes after the IV infusion was started, 20 mL of 2% lidocaine was injected through the epidural catheter. One-half hour later, a continuous epidural infusion of 2% lidocaine at 10 mL/h was begun. The epidural infusion was temporarily decreased to 5 mL/h or 5 mL boluses were added to maintain a T8 analgesic level. Arterial blood samples were analyzed for plasma lidocaine concentrations regularly during and for 5 h after surgery. Plasma lidocaine concentrations increased continuously during the epidural infusion and, despite wide individual variation, were similar for the two groups throughout the observation period. During the observation period, the mean maximal plasma lidocaine concentration was 5.8 +/- 2.3 microg/mL in the control group and 5.7 +/- 1.2 microg/mL in the dopamine group. However, the mean hourly lidocaine requirement during surgery was significantly different, 242 +/- 72 mg/h for control and 312 +/- 60 mg/h for dopamine patients (P < 0.03). At the end of Hour 4, the last period when all 20 patients were still receiving the epidural lidocaine infusion, the total lidocaine requirement was significantly different, 1088 +/- 191 mg for the control group and 1228 +/- 168 mg for the dopamine group (P < 0.05). Despite very large total doses of epidural lidocaine (1650 +/- 740 mg, control patients, and 1940 +/- 400, dopamine patients) mean maximal plasma concentrations remained below 6 microg/mL, and no patient exhibited signs or symptoms of toxicity. We conclude that small-dose IV dopamine increased epidural lidocaine requirements, presumably as a consequence of increased metabolism. IMPLICATIONS: We tested dopamine, a drug that increases liver metabolism of the local anesthetic lidocaine to determine if it would prevent excessively large amounts of lidocaine in the blood during prolonged epidural anesthesia in elderly patients. Dopamine did not alter the blood levels of lidocaine, but it did increase the lidocaine dose requirement to maintain adequate epidural anesthesia.     

Combining epidural fentanyl and lidocaine for postoperative pain.

Fifteen patients undergoing total hip and total knee replacement were studied prospectively to evaluate postoperative pain relief provided by an epidural infusion of fentanyl citrate, with and without lidocaine hydrochloride, and changes in arterial flow to the lower extremities. The patients were randomly placed in three groups: group 1 received epidural fentanyl, 5 micrograms/mL; group 2 received epidural fentanyl, 5 micrograms/mL with 0.75% solution of lidocaine; and group 3 received epidural fentanyl, 5 micrograms/mL with 1.0% solution of lidocaine. All patients received 1.5% solution of epidural etidocaine hydrochloride with epinephrine 1:200,000 for intraoperative anesthesia. No clinical evidence of deep vein thrombosis, tachyphylactic reaction to lidocaine, orthostatic hypotension, or motor block was demonstrated in any patient. The addition of lidocaine to the epidural fentanyl infusion did not improve pain relief or allow a decrease in the rate of infusion. Patients in all groups had improved arterial flow to the lower extremities 24 hours postoperatively.     

Disappearance of wheezing during epidural lidocaine anesthesia in a patient with bronchial asthma.

BACKGROUND AND OBJECTIVES: Local anesthetics in blood absorbed from the epidural space attenuate bronchial hyperreactivity to chemical stimuli. However, it is not documented whether local anesthetics at clinically relevant concentrations improve active wheezing in patients with bronchial asthma. CASE REPORT: We managed a 60-year-old man with bronchial asthma and active wheezing under continuous epidural anesthesia using plain lidocaine. The wheezing gradually diminished 20 minutes after the epidural injection of 13 mL 2% lidocaine and completely disappeared over 155 minutes during continuous epidural injection of 2% lidocaine (6 mL/h). The plasma concentrations of lidocaine in arterial blood during the epidural anesthesia ranged from 2.5 to 3.9 microg/mL. Wheezing reappeared 55 minutes after termination of the continuous epidural injection of lidocaine. The plasma concentration of lidocaine at this time was 1.9 microg/mL. CONCLUSIONS: At clinically relevant concentrations, lidocaine in the blood absorbed from the epidural space may improve bronchospasm in patients with bronchial asthma.     

Lidocaine metabolism associated with epidural anesthesia in patients for hepatic surgery

We measured plasma concentrations of lidocaine and its principal metabolite, monoethylglycinexylidide (MEGX) associated with thoracic epidural anesthesia using continuous infusion of lidocaine in 10 patients for hepatectomy and other 10 patients for elective abdominal surgery as a control. Plasma concentrations of lidocaine and MEGX were analysed by fluorescence polarization immunoassay and high performance liquid chromatography, respectively. Plasma lidocaine concentration increased gradually, and peaked to 5.1 +/- 2.3 micrograms.ml-1 (mean +/- SD) at the end of surgery in the hepatectomy group, but not in the control group. No significant differences were observed in plasma MEGX concentration between these two groups. Our findings suggest that MEGX formation by the hepatic cytochrome P-450 system might be impaired associated with hepatic surgery. Hypoperfusion of the liver induced by surgical manipulation may have contributed to this impaired metabolism.     

Effect of dopamine on lidocaine metabolism in patients after partial liver resection--a pharmacokinetic analysis

Pharmacokinetic changes in plasma lidocaine after bolus injection (1mg.kg-1) with or without dopamine infusion (3 micrograms.kg-1.min-1) were studied on patients who had a partial resection of the liver under enflurane-nitrous oxide anesthesia. Dopamine infusion was started in 10 minutes after endotracheal intubation. Serum concentrations of lidocaine and MEGX were measured by HPLC. The areas under the plasma lidocaine time-concentration curves were calculated after the administration of the drug into the peripheral vein or portal vein. The liver's extraction rate of lidocaine was evaluated by an equation based on the areas under the two time-concentration curve. The average extraction rate in the group with dopamine infusion was significantly higher than that in the group without dopamine. No significant difference was found in the ratio of AUC of MEGX to that of lidocaine between the group to which dopamine was administered and the control group.     

Comparison of analgesia induced by continuous epidural infusion of plain 1% lidocaine and 1% lidocaine prepared by dilution of 2% lidocaine with the same volume of saline

STUDY OBJECTIVE: To compare the extent of sensory block induced by continuous epidural infusion of plain 1% lidocaine and 2% lidocaine diluted with saline to 1% lidocaine. DESIGN: Prospective, randomized, blinded study. SETTING: University hospital. PATIENTS: 40 ASA physical status I inpatients scheduled for lower extremity orthopedic surgery. INTERVENTIONS: After surgery with lumbar epidural anesthesia with 0.75% ropivacaine, patients were randomized to two postoperative epidural infusion groups to receive plain 1% lidocaine (plain group) or 2% lidocaine diluted with the same volume of normal saline (dilution group). Continuous epidural infusion was started at a rate of 6 mL/h. MEASUREMENTS AND MAIN RESULTS: Regression of sensory block was significantly prolonged in the plain group, resulting in a significant difference in the spread of sensory block between the two agents from 4 to 6 h postoperatively. There also was a significant difference from the two groups in the level of motor block (modified Bromage scale) between 3 and 5 h postoperatively. CONCLUSIONS: Two percent lidocaine diluted with the same volume of saline is a less potent than the plain 1% lidocaine. The effect of saline as a diluent on epidurally administrated local anesthetics may be of clinical importance.     

Effect of standard diluted epinephrine infusion on epidural anesthesia in labor

BACKGROUND AND OBJECTIVES: Epinephrine is used with local anesthetics to prolong the duration of epidural analgesia and decrease the peak plasma concentrations of local anesthetics. However, the duration of labor may be prolonged because epinephrine reduces uterine activity. We designed a prospective, randomized, and doubleblind study to examine the effects of epinephrine infusion on the quality of analgesia and plasma concentration of local anesthetic, as well as the effect on the uteroplacental circulation, duration of the first or second stage of labor, and fetal outcome. METHODS: Twenty-four parturients received continuous epidural bupivacaine 0.125% (8 mL/h) combined either with epinephrine (40 microg/h) (n = 12) or without epinephrine (n = 12) for analgesia during labor. If patients requested additional analgesia, a bolus of 1% or 1.5% lidocaine (6 to 10 mL) was given. RESULTS: Only the plain bupivacaine group required additional lidocaine. However, epinephrine infusion prolonged the median (range) duration of the second stages of labor: 69 (21 to 231) minutes with epinephrine group versus 31 (8 to 99) minutes without epinephrine group (P < .05), and decreased pH in umbilical artery at the time of delivery. Epinephrine infusion did not change the uterine and umbilical blood flow, which were determined as the resistance indices. Changes in the fetal heart rate and Apgar score were also comparable. Epinephrine significantly reduced the umbilical venous to maternal arterial bupivacaine concentration (P < .05). CONCLUSIONS: A standard diluted epinephrine infusion (40 microg/h) into epidural space decreased anesthetic requirements. The possibility of the prolonged duration of labor remains a problem.     

Epidural lidocaine for cesarean delivery of the distressed fetus

Lidocaine with epinephrine and sodium bicarbonate has a rapid onset of action. We therefore wished to compare its use with that of chloroprocaine for urgent cesarean delivery. Thirty parturients for cesarean section under epidural anesthesia were divided into three groups. Group 1 required elective cesarean section and served as the control group for neonatal lidocaine levels. Groups 2 and 3 had been receiving epidural infusions of 0.125% bupivacaine with epinephrine 1:400,000 and required urgent cesarean section. They were randomized to receive either 1.5% lidocaine with epinephrine or 3% chloroprocaine, both with sodium bicarbonate 2 ml in a total volume of 25 ml. All patients had adequate anesthesia and none required supplementation. The time from completion of injection to the achievement of a T4 sensory level was significantly shorter in the chloroprocaine group (3.1 vs. 4.4 min). There were no differences in Apgar scores or Neurologic and Adaptive Capacity Scores between the lidocaine and chloroprocaine groups. Lidocaine was detectable in maternal serum from four of the urgent cases and all of the elective cases. It was detectable in five neonates from the elective group but none from the emergency group. In parturients with preexisting epidural catheters and a baseline epidural infusion to maintain a T10 sensory level, chloroprocaine is faster in onset than lidocaine, but the difference in this study was only 1.3 min, and both agents provided excellent anesthesia.     

Circulatory stability and plasma lidocaine levels during continuous and intermittent thoracic epidural analgesia

Circulatory stability and plasma levels of lidocaine were investigated in 20 patients who received thoracic epidural analgesia with plain lidocaine during elective abdominal surgery under general anesthesia. In one group, bolus injection of 8ml of 2% lidocaine was followed by volumetric continuous pump-driven infusion (CPI) of 8ml of 1.5% lidocaine per hour. In the other group, the same initial bolus injection was followed by repetitive intermittent bolus infusions (RII) of 6ml of 1.5% lidocaine at a 45 min-interval. Circulatory stability was evaluated by a discriminant function. The results showed that epidural analgesia produced smaller circulatory fluctuations with CPI than with RII. Venous plasma lidocaine levels were consistently higher with CPI than with RII. Plasma levels increased stepwise with RII and kept constant with CPI. Differences in plasma levels were significant from 20min after the initial injection to 135min. We therefore conclude that epidural analgesia with CPI is superior to that with RII. However, it must be remembered that higher plasma levels may occur with CPI than with RII.(Kawamoto M, Sera A, Tanaka H, et al.: Circulatory stability and plasma lidocaine levels during continuous and intermittent thoracic epidural analgesia. J Anesth 5: 166–171, 1991)     

Local infiltration of epinephrine-containing lidocaine with bicarbonate reduces superficial bleeding and pain during labor epidural catheter insertion: a randomized trial

BACKGROUND: Superficial bleeding after labor epidural catheter placement is a common phenomenon. In addition to delaying securing the epidural catheter, it may loosen the adhesive catheter dressing. The primary aim of this study was to determine whether skin infiltration with epinephrine-containing rather than plain lidocaine reduces superficial bleeding after catheter placement. Secondary objectives were to determine whether adding epinephrine and/or sodium bicarbonate affected infiltration pain. METHODS: After institutional review board approval and informed consent, 80 healthy women receiving epidural analgesia during labor were randomly assigned in a double-blind manner to four local anesthetic mixtures (n=20 in each group): group L: lidocaine 1.5%, group LB: lidocaine 1.5% with 8.4% sodium bicarbonate, group LE: lidocaine 1.5% with epinephrine 1:200000, and group LEB: lidocaine 1.5% with epinephrine 1:200000 and 8.4% sodium bicarbonate. Clinical endpoints included the amount of superficial bleeding at the catheter site, pain during local anesthetic infiltration and epidural catheter movement during labor. RESULTS: Demographic data were similar among the groups. The addition of epinephrine to lidocaine significantly reduced superficial bleeding. Solutions containing epinephrine were well tolerated and caused no cardiovascular disturbances. The addition of epinephrine did not increase pain, while bicarbonate reduced it [verbal score (scale 0-10) 3.6+/-2.2 vs. 2.6+/-1.8; P=0.04]. There were no differences in epidural catheter movement among the groups; no catheters became displaced during labor. CONCLUSION: Local infiltration of epinephrine-containing lidocaine before epidural catheter insertion reduces superficial bleeding and the addition of bicarbonate decreases pain during skin infiltration.     

Hospital discharge after ambulatory knee arthroscopy: A comparison of epidural 2-chloroprocaine versus lidocaine

BACKGROUND AND OBJECTIVES: This prospective, randomized, double-blind study compares the efficacy of epidural 2-chloroprocaine and lidocaine for attaining hospital discharge criteria after ambulatory knee arthroscopy. We hypothesized that 2-chloroprocaine would facilitate earlier discharge than lidocaine. METHODS: American Society of Anesthesiologists (ASA) I and II patients were randomized to receive equipotent doses of epidural 3% 2-chloroprocaine or 1.5% lidocaine, both without epinephrine. Time to block resolution and discharge were compared between groups, along with the need for epidural reinjection, surgical times, and postoperative back pain. RESULTS: Twenty-seven patients completed the study, 13 in the 2-chloroprocaine group and 14 in the lidocaine group. The 2-chloroprocaine group was ready for discharge significantly earlier than the lidocaine group (130 +/- 17 min [range, 105 to 160] v 191 +/- 32 min [range 144 to 251]; P <.0001, 90% power). The lidocaine group required more epidural reinjections. Anesthesia-related side effects were similar in both groups. CONCLUSIONS: Epidural 3% 2-chloroprocaine without epinephrine is an advantageous choice for ambulatory knee arthroscopy. It enables readiness for discharge an hour sooner than 1.5% lidocaine, requires fewer reinjection interventions, and may reduce delayed discharge secondary to prolonged time to void. This clinical study shows the superiority of epidural 3% 2-chloroprocaine over 1.5% lidocaine for expediting hospital discharge after ambulatory surgery.     

Patient-controlled lidocaine analgesia for acromioplasty surgery

Twenty-four consecutive patients undergoing shoulder acromioplasty were given postoperative analgesia with a new method in which a patient-controlled continuous infusion of lidocaine infiltrated the subacromial space. Seventeen of the acromioplasties were done with arthroscopy, whereas 7 were performed with an open procedure. A 2% solution of lidocaine without epinephrine was used for both a continuous dose of 2 cc/h and patient-controlled interval doses of 1 cc administered at 15-minute intervals. The catheter was left in place for 72 hours. We prospectively studied complications, the patient's subjective pain level, the amount of supplementary pain medication used, and serum levels of lidocaine. In addition, we evaluated a control group of 24 patients undergoing acromioplasty by the same surgeon without the use of this method of pain control. No wound complications occurred. No adverse reactions to lidocaine or overdose of lidocaine occurred. Blood levels of lidocaine averaged 0.3 microgram/mL in the 12 patients studied. Subjective pain levels and the amount of supplementary pain medication used were both lower in the group receiving patient-controlled lidocaine analgesia at statistically significant levels (P = .168 measuring subjective pain level, and P = .0212 measuring supplementary pain medication use). Patient-controlled lidocaine analgesia in the subacromial space appears to be a safe method for achieving high levels of pain control in patients undergoing an acromioplasty.