Reduction in injection pain using buffered lidocaine as a local anesthetic before cardiac catheterization. Neutralizing pH of lidocaine reduces pain during Norplant system insertion procedure. Randomized trial of buffered versus plain lidocaine for local anaesthesia in open carpal tunnel decompression. Efficacy of alkalinized lidocaine for reducing pain on intravenous and epidural catheterization. Comparison of three modified lidocaine solutions for use in eyelid anesthesia. Capacity of the clinical picture to characterize low back pain relieved by facet joint anesthesia. Proposed criteria to identify patients with painful facet joints. Establishing intravenous access: a study of local anesthetic efficacy. Comparison of the efficacy of different local anesthetics and techniques of local anesthesia in therapeutic abortions. Evaluation of lidocaine as an analgesic when added to hypertonic saline for sclerotherapy. Unpreserved lidocaine to control discomfort during cataract surgery using topical anesthesia. Safety and efficacy of intracameral injections of unpreserved lidocaine to reduce intraocular sensation. A trial of intravenous lidocaine on the pain and allodynia of postherpetic neuralgia. A comparison of patient comfort during cataract surgery with topical anesthesia versus topical anesthesia and intracameral lidocaine. Concentration-effect relationship of intravenous lidocaine on the allodynia of complex regional pain syndrome types I and II. Comparison of lidocaine injection, botulinum toxin injection, and dry needling to trigger points in myofascial pain syndrome. Intravenous lidocaine in central pain: a double-blind, placebo-controlled, psychophysical study. Carpal ligament decompression under local anaesthesia: the effect of lidocaine warming and alkalinisation on infiltration pain. Local anesthesia for cryosurgery on the cervix. A double-blind randomized comparison of lidocaine and saline for cervical anesthesia. Buffered lidocaine for skin infiltration prior to hemodialysis. Intradermal anesthesia and comparison of intravenous catheter gauge.
Previous reports have suggested that pain associated with the injection of lidocaine is related to the acidic pH of the solution. To determine if the addition of a buffering solution to adjust the pH of lidocaine into the physiologic range would reduce pain during injection, we performed a blinded randomized study in patients undergoing cardiac catheterization. Twenty patients were asked to quantify the severity of pain after receiving standard lidocaine in one femoral area and buffered lidocaine in the opposite femoral area. The mean pain score for buffered lidocaine was significantly lower than the mean score for standard lidocaine (2.7 +/- 1.9 vs. 3.8 +/- 2.2, P = 0.03). The pH adjustment of standard lidocaine can be accomplished easily in the catheterization laboratory before injection and results in a reduction of the pain occurring during the infiltration of tissues. The acidity of lidocaine used as a local anesthetic during the insertion of Norplant System capsules can cause patient discomfort. Buffering lidocaine with sodium bicarbonate significantly reduced pain scores reported by 46 women who participated in this randomized, double-blind study. Derived from a pain scale of 1 to 10, the mean difference in reported pain scores with and without buffering was 1.17 (P = 0.0098) with women using themselves as controls, for an average reduction in pain of 29%. Because this added step minimized patient discomfort, it might make the Norplant System a more attractive option for women apprehensive about insertion pain. We performed a randomized double-blind case-control study in 64 consecutive patients undergoing open carpal tunnel decompression under local anaesthetic to assess the pain experienced on injection of plain lidocaine (pH 6.4) compared with lidocaine buffered with sodium bicarbonate (pH 7.4). The results showed no statistical difference in the pain scores reported by patients. The mean pain scores for all patients were low, and most patients reported that they were "not at all anxious" about receiving a similar injection in the future. To investigate whether increasing the pH of lidocaine could reduce the pain caused by its skin infiltration as well as that caused by intravenous and epidural needle insertion.
                A randomized, double-blind trial was undertaken in patients who were allocated to receive topical anesthesia with either plain (plain group; n = 25) or alkalinized lidocaine (alkalinized group; n = 25). An alkalinized lidocaine solution was prepared by adding 8.4% sodium bicarbonate to a plain 1% lidocaine solution at a ratio of 1 : 10. Pain was assessed using the verbal analog scale (VAS).
                In the alkalinized group, the VAS scores on skin infiltration in the hand (2.5 +/- 1.4) and the back (2.7 +/- 1.4) were significantly lower than the respective scores in the plain group (3.5 +/- 1.4, and 4.9 +/- 1.9). Although the VAS score on intravenous needle insertion did not differ between the two groups, the VAS score on epidural needle insertion was significantly lower in the alkalinized group (1.3 +/- 1.0) than in the plain group (3.6 +/- 1.3).
                Alkalinization of lidocaine was effective in attenuating pain on skin infiltration and on epidural needle insertion. To compare pain on injection and the efficacy of anesthesia of three modified lidocaine solutions for use in eyelid surgery: 1) 2% lidocaine with 1:100,000 epinephrine, 2) 2% lidocaine with 1:100,000 epinephrine buffered 9:1 with 8.4% sodium bicarbonate, and 3) 2% lidocaine with 1:100,000 epinephrine diluted 1:9 with 0.9% bacteriostatic saline solution (with benzyl alcohol).
                In this prospective, randomized, double-masked, controlled clinical trial, 30 consecutive patients undergoing bilateral identical eyelid surgery were randomized to one of three treatment groups. Group 1 received buffered solution on one side and stock solution on the other, group 2 received bacteriostatic saline diluted solution on one side and stock solution on the other, and group 3 received buffered solution on one side and bacteriostatic saline diluted solution on the other. Patients used a 5-point scale to rate the perceived pain on injection and the pain felt during the operative procedure.
                Comparison of mean injection pain scores showed that buffered solution was significantly less painful than unmodified solution (2.2 versus 3.1, p < 0.05), bacteriostatic saline modified solution was significantly less painful than unmodified solution (0.9 versus 3.3, p < 0.05), bacteriostatic saline modified solution was significantly less painful than buffered solution (1.2 versus 2.3, p < 0.05). Comparison of mean intraoperative pain scores demonstrated no significant difference between the solutions in any of the treatment groups.
                For local anesthesia in eyelid surgery, bacteriostatic saline modified solution provides more comfort on injection than either buffered or unmodified lidocaine-epinephrine solution and provides an adequate level of anesthesia that does not differ significantly from either the buffered or unmodified solutions. Prospective randomized study to compare the efficacy of facet joint injection with lidocaine and facet joint injection with saline in two groups of patients with low back pain, with and without clinical criteria that were determined in a previous study to implicate the facet joint as the primary source of the pain.
                To assess the efficacy of single facet joint anesthesia versus placebo (saline injections) and to determine clinical criteria that are predictive of significant relief of LBP after injection.
                There is no syndrome that discriminates between lower back pain caused by facet joint and that caused by other structures. Single or double facet joint anesthesia, and single photon emission computed tomography are expensive and time-consuming procedures for selecting patients in controlled clinical trials with large populations.
                Results of a previous study showed that seven clinical characteristics were more frequent in patients who responded to facet joint anesthesia than in those who did not. In the current study, a group of 43 patients with lower back pain who met at least five criteria were compared with 37 patients who met fewer criteria. Patients randomly received injection of either lidocaine or saline into the lower facet joints. The result was considered positive if more than 75% pain relief was determined by visual analog scale. The patient, the radiologist, and the investigator were blinded. An analysis of variance was used to seek an interaction between clinical group effect and injection effect, and logistic regression analysis to select the best set of variables that would be predictive of minimum pain relief of 75% after the injection.
                There was a significant interaction between clinical group and injection effect (P = 0.003). In patients with back pain, lidocaine provided greater lower-back pain relief than saline (P = 0.01). Lidocaine also-provided greater pain relief in the back pain group than in the nonpain group (P = 0.02). The presence of five among seven variables (age greater than 65 years and pain that was not exacerbated by coughing, not worsened by hyperextension, not worsened by forward flexion, not worsened when rising from flexion, not worsened by extension-rotation, and well-relieved by recumbency), always including the last item, distinguished 92% of patients responding to lidocaine injection and 80% of those not responding in the lidocaine group.
                A set of five clinical characteristics can be used in randomized studies to select lower back pain that will be well relieved by facet joint anesthesia. These characteristics should not, however, be considered as definite diagnostic criteria of lower back pain originating from facet joints. We performed a double-blind, randomized, prospective study to determine the local anesthetic that provided the best analgesia for insertion of an 18-gauge intravenous (i.v.) catheter and to determine whether alkalinization of lidocaine decreases the pain of intradermal injection. There were 280 healthy adult patients assigned randomly to seven different groups: benzyl alcohol 0.9% in normal saline, 2-chloroprocaine 3%, lidocaine 1%, lidocaine 1% with preservative, alkalinized lidocaine 1% with preservative, normal saline, and a control group that received i.v. catheter placement without previous drug injection. A 10-cm visual analog pain scale (VAPS) was used to obtain pain scores after pre-i.v. drug injection and after iv catheter insertion. Benzyl alcohol in normal saline (0.61 +/- 0.11) and alkalinized lidocaine (0.69 +/- 0.10) had the lowest mean pain scores for drug injection and these were significantly different from other drugs (P < 0.05). Alkalinized lidocaine (0.7 +/- 0.18) had the lowest mean pain score for i.v. catheter insertion with nothing (no previous drug injected) (3.47 +/- 0.38) and normal saline (3.97 +/- 0.18) had the highest mean pain scores (P < 0.05). We conclude that alkalinized lidocaine decreased the pain associated with its injection. Alkalinized lidocaine was the best local anesthetic for i.v. catheter placement. Benzyl alcohol in normal saline was also effective. The objectives of this study were to determine whether carbonated or plain lidocaine provides better pain control during abortions and to determine whether deep injections of lidocaine provide better pain control than regular injections of lidocaine.
                Phase 1 was a prospective, randomized, double-blind trial comparing 10 cm3 of 2% carbonated lidocaine with plain lidocaine. In phase 2 the plain lidocaine group in phase 1 was compared prospectively with the next group of patients, in whom a new technique of deep injection was used. A pain scale was administered by the counselor after dilatation and at the end of the procedure.
                The improvement in pain scores with carbonated lidocaine was 8%. The improvement with the deep injection technique was 25%.
                The improvement in pain scores with deep injection was clinically significant and is recommended. The efficacy of sclerosing agents for the treatment of telangiectasias and reticular veins is well established. The injection of these agents is often associated with pain, and it is not uncommon for sclerotherapists to include lidocaine with the sclerosants in an attempt to reduce the pain associated with treatment. However, there are concerns that this may reduce the overall efficacy of the treatment because of dilution of the sclerosant. Patient comfort and overall outcome associated with treatment using HS with lidocaine (LIDO) versus that using HS alone was compared.
                Forty-two patients were prospectively entered into the study and randomized blindly to sclerotherapy with 23.4% HS or 19% LIDO. Study subjects and treating physicians were blinded to the injection solution used. Injection sites were chosen for veins ranging in size from 0.1 to 3 mm. Photographs of the area to be treated were taken, and the patients rated their pain. They were then observed at regular intervals for four months, and clinical data was collected. Thirty-five subjects completed the full follow-up period, and photographs of the injected area were taken again. Three investigators blinded to the treatment assignment then evaluated the photographs and scored the treatment efficacy according to a standardized system.
                In the HS group, 61.9% (13 of 21) patients rated their pain as none or mild, whereas 90.5% (19 of 21) of patients in the LIDO group had no or mild discomfort. This difference is significant, with a P value of.034. There was no difference in the overall efficacy of treatment between the two groups. The groups had similar rates of vein thrombosis and skin necrosis.
                Although lidocaine is often used with sclerosing agents, there are no previous reports in the literature to evaluate its effectiveness in reducing the pain experienced by the patient. In this study, patients receiving LIDO experienced significantly less discomfort at the time of injection than patients who received HS alone. There were no differences in the effectiveness of treatment or in the incidence of complications between the two groups. To determine whether intraoperative unpreserved lidocaine further decrease discomfort or pain during sutureless small incision cataract surgery and intraocular lens (IOL) implantation under topical anesthesia.
                Outpatient ambulatory surgical center.
                In this prospective controlled study, comparable eligible patients were randomized to receive 0.1 cc unpreserved lidocaine 1% or 0.1 cc balanced salt solution (BSS) (control group) in double-masked fashion. Study drugs were injected intracamerally 1 minute before phacoemulsification. A predefined uniform pain/discomfort scale was used for assessment during phacoemulsification and IOL insertion. A secondary study using a 0.5 cc dose was also performed.
                Twenty-six percent in the control group and 9% in the lidocaine group had discomfort pain scores of 2 or more; 10% in the BSS group felt increased pressure or pain during phacoemulsification. In the lidocaine group, discomfort was felt mainly during IOL insertion, possibly as a result of wound manipulation. During phacoemulsification, no patient in the lidocaine group reported pain; 2% felt increased pressure during phacoemulsification. A dose increase to 0.5 cc reduced any intraocular sensation to 3% in the lidocaine group. No patient in either group had significant cell loss or adverse events.
                Intraoperative lidocaine is safe and effective in controlling intraoperative discomfort. To determine the safety and efficacy of intracameral injections of unpreserved lidocaine to reduce intraocular sensation.
                Carolina Eye Associates, Southern Pines, North Carolina, USA.
                In this prospective study, 100 patients having phacoemulsification under topical anesthesia were randomly assigned to receive an intracameral injection of unpreserved lidocaine (0.5 cc of a 1% unpreserved solution) or balanced salt solution.
                Ninety-three patients completed the study. There were no significant between-group differences in cell density parameters or Kowa laser flare-cell meter measurements. Seventy-eight percent of lidocaine patients and 56% of controls reported no sensation (P = .048, Fisher's exact test).
                Intracameral injections of unpreserved lidocaine safely and effectively reduced intraocular sensation during phacoemulsification. This study investigated the effect of intravenous lidocaine at two doses (1 mg/kg and 5 mg/kg over 2 hours) and an intravenous saline placebo on the pain and allodynia of postherpetic neuralgia (PHN). Twenty-four patients were studied using a randomized, double-blind, within-patient crossover design. Each patient received normal saline, lidocaine 0.5 mg/kg/h, and lidocaine 2.5 mg/kg/h for a 2-h period. The McGill Pain Questionnaire Short Form, visual analogue scores (VAS), and area of allodynia were measured at intervals during the infusions. Free plasma lidocaine levels were also measured. The results were statistically analyzed using Student's t-test for paired data. The VAS for ongoing pain showed a significant reduction after all the infusions (P < 0.05). For dynamic pressure-provoked pain, the VAS was unaffected by placebo but showed a reduction at an equal level of significance with both lidocaine infusions (P < 0.05). The area of allodynia of PHN, as mapped by brush stroke, declined in association with intravenous lidocaine (0.5 mg/kg/h = P < 0.05; 2.5 mg/kg/h = P < 0.001). Placebo had no significant effect on the area of allodynia. These findings demonstrate a positive effect on pain and allodynia following a brief intravenous infusion of lidocaine. The higher dose infusion may produce plasma levels in the toxic range, with no significant clinical increase in response. To determine whether intraocular lidocaine increases patient comfort during cataract surgery while under topical anesthesia.
                Prospective, randomized, double-masked, placebo-controlled clinical trial.
                Both men and women between 45 and 85 years of age who were scheduled for elective cataract surgery while under topical anesthesia participated. Sixty-eight patients were randomized to each group.
                Patients were randomized to receive either topical anesthesia plus intracameral 1% preservative-free lidocaine or intracameral balanced salt solution.
                Patient assessment of pain during delivery of the anesthesia, surgery, and after surgery using a visual analog pain scale was measured. Patients also recorded the degree to which they were bothered by tissue manipulation and the microscope light. Surgeon assessments of operative conditions, patient cooperation, and intraoperative complications were recorded. The attending anesthesiologist recorded any required supplemental intravenous sedation and any increase in pulse or increase in blood pressure.
                There was no significant difference in patient-reported pain scores for delivery of anesthesia (P = 0.902), surgery (P = 0.170), or after surgery (P = 0.680). Patients in the lidocaine group reported being less bothered by tissue manipulation (P = 0.021). The surgeon assessment showed more patient cooperation in the lidocaine group (P = 0.043).
                Both topical anesthesia alone and topical anesthesia plus intracameral lidocaine provide good operative conditions for the surgeon and comfortable surgical circumstances for the patient. Injection of intraocular lidocaine increases patient cooperation and decreases the degree to which patients are bothered by tissue manipulation, two outcomes that justify its use. Several lines of evidence suggest that neuropathic pain (including Complex Regional Pain Syndrome [CRPS] I and CRPS II) is mediated in part by an increase in the density of voltage-sensitive sodium channels in injured axons and the dorsal root ganglion of injured axons. This study sought to characterize the effects of intravenous lidocaine (a sodium channel blocker) on acute sensory thresholds within the painful area and the size of the painful area in patients suffering from CRPS I and II.
                This study used a randomized, double-blind, placebo-controlled design in 16 subjects suffering from CRPS I and II with a prominent allodynia. Each subject received an intravenous infusion of lidocaine and diphenhydramine separated by 1 week. A computer-controlled infusion pump targeted stair-step increases in plasma levels of lidocaine of 1, 2, and 3 microg/ml. At baseline and at each plasma level, spontaneous and evoked pain scores and neurosensory testing within the painful area were measured. The neurosensory testing consisted of thermal thresholds, tactile thresholds and the area of allodynia to punctate, and stroking and thermal stimuli.
                Intravenous lidocaine and diphenhydramine had no significant effect on the cool, warm, or cold pain thresholds. However, lidocaine caused a significant elevation of the hot pain thresholds in the painful area. Intravenous lidocaine caused a significantly decreased response to stroking and cool stimuli in the allodynic area. There was also a significant decrease in pain scores to cool stimuli at all plasma levels and the spontaneous pain at the highest plasma level.
                This study demonstrates that intravenous lidocaine affects pain in response to cool stimuli more than mechanical pain in subjects with neuropathic pain. There is a lesser effect on spontaneous pain and pain induced by stroking stimuli and no effect on the pain induced by punctate stimuli. Myofascial pain syndrome (MPS) is one of the most common causes of chronic musculoskeletal pain. Several methods have been recommended for the inactivation of trigger points (TrP).
                This prospective, single-blind study was proposed to compare TrP injection with botulinum toxin type A (BTX-A) to dry needling and lidocaine injection in MPS.
                Eighty-seven trigger points (cervical and/or periscapular regions) in 23 female and six male patients with MPS were treated and randomly assigned to three groups: lidocaine injection (n=10, 32 TrP), dry needling (n=10, 33 TrP), and BTX-A injection (n=9, 22 TrP).
                Clinical assessment including cervical range of motion, TrP pain pressure threshold (PPT), pain scores (PS), and visual analog scales for pain, fatigue, and work disability were evaluated at entry and the end of the 4th week. Additionally, depression and anxiety were evaluated with the Hamilton depression and anxiety rating scales, and quality of life was assessed using the Nottingham health profile (NHP). The subjects were also asked to describe side effects. INJECTION PROCEDURE: One milliliter of 0.5% lidocaine was administered to each TrP in the lidocaine injection group, 10-20 IU of BTX-A to each TrP in the BTX-A group, and dry needling to each TrP in the last group, followed by stretching of the muscle groups involved. The patients were instructed to continue their home exercise programs.
                Pain pressure thresholds and PS significantly improved in all three groups. In the lidocaine group, PPT values were significantly higher than in the dry needle group, and PS were significantly lower than in both the BTX-A and dry needle groups. In all, visual analog scores significantly decreased in the lidocaine injection and BTX-A groups and did not significantly change in the dry needle group. Disturbance during the injection procedure was lowest in the lidocaine injection group. Quality of life scores assessed by NHP significantly improved in the lidocaine and BTX-A groups but not in the dry needle group. Depression and anxiety scores significantly improved only in the BTX-A-injected group.
                Injection is more practical and rapid, since it causes less disturbance than dry needling and is more cost effective than BTX-A injection, and seems the treatment of choice in MPS. On the other hand, BTX-A could be selectively used in MPS patients resistant to conventional treatments. To investigate the effects of systemic administration of lidocaine on different components of neuropathic central pains by quantitative sensory testing.
                The efficacy of systemic lidocaine (5 mg/kg IV over 30 minutes) was evaluated in a double-blind, placebo-controlled, and cross-over fashion, on both spontaneous ongoing pain and evoked pains (allodynia and hyperalgesia) in 16 patients with chronic poststroke (n = 6) or spinal cord injury (n = 10) related pain.
                Lidocaine was significantly superior to the placebo (saline) in reducing the intensity of spontaneous ongoing pain for up to 45 minutes after the injection: 10 of 16 patients (62.5%) receiving lidocaine showed a significant reduction in spontaneous pain, whereas only six patients showed this after the placebo. Lidocaine also significantly reduced the intensity of brush-induced allodynia and mechanical hyperalgesia, but was no better than the placebo against thermal allodynia and hyperalgesia. In general, the side effects were moderate and consisted mainly of lightheadedness (44%).
                Systemic lidocaine can induce a significant and selective reduction of several components of pain caused by CNS injuries. The observed preferential antihyperalgesic and antiallodynic effects of this drug suggest a selective central action on the mechanisms underlying these evoked pains. This study investigated the effects of alkalinization and warming of lidocaine 1% on injection pain in patients undergoing carpal tunnel decompression. Sixty-four adult patients were randomly allocated into one of three groups: Group A (n=20) received plain lidocaine 1%, Group B (n=22) alkalinized lidocaine and Group C (n=22) warmed and alkalinized lidocaine. Pain on needle insertion and on infiltration was assessed using a 100mm Visual Analogue Scale (VAS). There was no significant difference regarding pain on needle insertion whereas significant differences were noted in reference to infiltration pain. In Groups B and C (alkalinized lidocaine) the VAS scores on skin infiltration were significantly lower than in Group A, while the pain score in Group C (alkalinized and warmed lidocaine) was significantly lower than in Group B. Forty-five patients were evaluated in a prospective, randomized study to determine the effectiveness of a local injection of lidocaine in reducing pain during cervical cryosurgery. Study patients received a submucosal cervical injection of 1% lidocaine with a 1:100,000 dilution of epinephrine. Control patients did not receive an injection. Both groups received a single dose of naproxen sodium or ketoprofen prior to the procedure. The patient and the observing nurse recorded the pain experienced with a visual analog scale (VAS). Nurse and patient response for the control and study groups showed a high correlation (r = .573 and P < .01, r = .673 and P < .001, respectively). The mean VAS score recorded for the 26 control patients was 4.27, significantly greater than the mean score for the 19 study patients, 1.16 (P < .001). These findings indicate that a submucosal local injection of lidocaine with epinephrine is effective in reducing pain during cervical cryosurgery. To compare bacteriostatic saline and buffered lidocaine for cervical anesthesia to blunt the reported pain during brief suction curettage.
                A double-blind randomized clinical trial was conducted on women presenting for pregnancy termination procedures. Participants received either paracervical submucosal injections of bacteriostatic saline or 1% buffered lidocaine just before cervical dilation. Self-reported pain intensity was assessed at three time points during and 30 minutes after the procedure.
                Fifty-two of 135 eligible women presenting for pregnancy termination procedures participated in the study. Pain intensity ratings in lidocaine and saline treatment subjects did not differ significantly at any point. Our study had a power of 0.94 to detect more than a 15% difference on the 21-point box scale between the two solutions. Only one patient requested her block be repeated, and she had received lidocaine originally. Furthermore, of those women receiving lidocaine, 11% reported mild toxicity symptoms.
                To minimize lidocaine toxicity for a brief suction curettage procedure, bacteriostatic saline or very dilute lidocaine could be considered for the paracervical injection solution. The local anesthetic mechanism may be distention rather than blockage of specific autonomic nerves when there is no waiting period. This would mean that the term paracervical block could be changed to cervical anesthesia. This study compared the effects of buffered versus unbuffered lidocaine when used as local anesthetic in preparation for cannulation of the arterial and venous sites of children requiring hemodialysis. The subjects for this study were seven children, ages 6-18 years, observed during 101 dialysis treatments. For each subject undergoing hemodialysis on a given day, one syringe containing 1% lidocaine (L) and one containing buffered lidocaine (BL) were prepared. The BL solution was prepared by adding 2 mL of 8.4% sodium bicarbonate to 20 mL of 1% lidocaine just prior to use. The choice of local anesthetic used for cannulation of the arterial or venous site was randomly assigned to be either L or BL. Nurses, raters, and subjects were blind to contents of the syringe. The procedures for piercing the skin, pausing, and infiltrating were standardized, as was the volume administered. Speed of injection was not controlled. Comparisons of self-reported pain and behavioral observations for L versus BL revealed no significant differences for pain of infiltration or pain of cannulation. Technique variables such as the speed of injection, which tended to be very slow for these children, appear to significantly influence infiltration pain and the relative merits of buffering. A double-blinded randomized prospective study was performed to determine whether alkalinization of lidocaine decreases the pain of intradermal injection and if a larger intravenous catheter (16 gauge) causes more discomfort on insertion than a smaller (20 gauge) catheter when intradermal anesthesia has been used. In a random manner, 100 patients received skin wheals with commercially prepared lidocaine or lidocaine with the addition of sodium bicarbonate before the insertion of a 16- or 20-gauge intravenous catheter. Visual analogue pain scores were obtained after the skin wheal was placed and after the intravenous catheter was inserted. There was no statistically significant difference in pain scores between the two local anesthetic solutions. However, the catheter insertions pain scores were slightly, but statistically significantly larger in the 16-gauge group regardless of local anesthetic solution used. The addition of sodium bicarbonate to commercially prepared lidocaine does not decrease the pain associated with an intradermal skin wheal. There is a slight increase in patient discomfort upon insertion of a large-bore intravenous catheter, even with the prior use of local anesthetic.
Increasing the pH of lidocaine decreased pain on injection and augmented patient comfort and satisfaction.