The effect of alkalinisation of lignocaine on axillary brachial plexus anaesthesia

Buffered lidocaine for paracervical blocks in first-trimester abortions: a randomized controlled trial

Objective

The objective was to evaluate if buffered lidocaine decreases injection pain as compared to plain lidocaine for paracervical blocks during first-trimester outpatient surgical abortions.

Study design

We conducted a randomized, double-blind, placebo-controlled trial among women undergoing outpatient uterine aspiration of a first-trimester pregnancy or an early pregnancy loss. Subjects received a paracervical block with either lidocaine 1% 20 mL or lidocaine 1% 18 mL plus sodium bicarbonate 8.4% 2 mL. The primary outcome was pain from injection of the paracervical block measured on a 100-mm visual analog scale (VAS). Secondary outcomes included pain after cervical dilation, uterine aspiration and overall satisfaction with pain control. Scores were compared using the Mann–Whitney U test. We aimed to detect a 15-mm difference in pain from injection of the paracervical block.

Results

From May 2017 to October 2018, 48 women received plain lidocaine and 50 women received buffered lidocaine. Groups were similar in demographics. We found no clinically or statistically meaningful difference in pain when evaluating median VAS scores for paracervical block injection between the buffered and plain lidocaine [30.0 (interquartile range (IQR) 15.3–64.5); 44.5 (IQR 18.3–65), respectively, p = .32]. We found no difference in secondary outcomes between buffered and plain lidocaine.

Conclusion

Buffered lidocaine for paracervical blocks in first-trimester outpatient surgical abortions does not decrease injection pain as compared to plain lidocaine.

Implications statement

Buffering the paracervical block in first-trimester outpatient surgical abortions does not decrease injection pain as compared to plain lidocaine, nor does it increase patient satisfaction. Eliminating sodium bicarbonate allows for a more cost-effective and readily available solution for paracervical blocks.

Comparison of Magnesium Sulfate and Ketamine with Ropivacaine in Supraclavicular Brachial Plexus Block: A Randomized Controlled Trial

Background:

Supraclavicular brachial plexus block offers good operating conditions with limited postoperative analgesia. Magnesium sulfate (MgSO₄) and ketamine block peripheral nociception mediated via N-methyl-D-aspartate receptors.

Aims:

The aim of this study was to evaluate the effect of MgSO₄ and ketamine on the duration of analgesia in brachial block.

Settings and Design:

This was a prospective, randomized, controlled double-blind study.

Materials and Methods:

One hundred and five adult patients were randomly divided into three groups: Group I = 27 mL of 0.5% ropivacaine; Group II = 27 mL of 0.5% ropivacaine + 250 mg MgSO₄; and Group II = 27 mL of 0.5% ropivacaine + 2 mg.kg⁻¹ ketamine. Normal saline was added to make a total volume of 30 mL. The onset and duration of the sensorimotor blockade, quality and duration of postoperative analgesia, and adverse effects were assessed.

Statistical Analysis:

Statistical analysis was performed using SPSS, version 17.0 software (SPSS, Inc., Chicago, IL, USA). Chi-square test was used for nonparametric and ANOVA for parametric data. Post hoc Student's paired t-test was applied wherever indicated. The results were expressed as mean and standard deviation or numbers (%). P < 0.05 was considered as statistically significant.

Results:

The duration of analgesia was significantly longer in Group II (8.78 ± 0.97 h) compared to Group I (6.76 ± 0.92 h; P < 0.001) and Group III (7.1 ± 0.89 h; P < 0.001). Intervention groups had lower postoperative visual analog scores at 8, 12, and 24 h compared to the control group. Sedation, nystagmus, and hallucinations were observed in Group III.

Conclusion:

The addition of MgSO₄ to ropivacaine in supraclavicular brachial plexus block significantly prolongs the duration of analgesia. MgSO₄ improves the quality of postoperative analgesia with lesser incidence of side effects when compared to ketamine.

NaHCO3-Buffered Lidocaine Gel for Outpatient Rigid Cystoscopy in Men

PURPOSE

The purpose of this study was to explore the effect of NaHCO3-buffered lidocaine gel as a topical anesthetic agent for pain relief for rigid cystoscopy.

DESIGN

Prospective randomized controlled trial.

METHODS

ASA I-II male patients undergoing rigid cystoscopy randomly received 10 mL 2% Carbocaine lidocaine gel with 1 mL 0.9% saline (group 1) or 1 mL 5% NaHCO3 solution (group 2). After 3 minutes exposure, the cystoscope was inserted into the urethra. On receiving the gel, cystoscope insertion, and intravesical observation, pain score was recorded using the visual analog scale.

FINDINGS

The gel pH with or without NaHCO3 was 7.20 and 6.41, respectively. The concentration of soluble lidocaine in the gel was stable for 24 hours or more. The visual analog scale score in group 2 was significantly lower (1.3 ± 0.9) than in group 1 (5.28 ± 1.99). No adverse effects were recorded.

CONCLUSION

Alkalized lidocaine gel resulted in successful analgesia for rigid cystoscopy in men without adverse effects.

WITHDRAWN: Adjusting the pH of lidocaine for reducing pain on injection

May 2015

This review was originally published in 2010 and at that time complied with Cochrane’s Commercial Sponsorship Policy. The Commercial Sponsorship policy was updated in 2014 (http://community.cochrane.org/organisational‐policy‐manual/appendix‐5‐commercial‐sponsorship‐policy ). This review is no longer compliant with that policy.

The non conflicted members of the original team of authors have decided not to update the review. We have therefore decided to withdraw the review and seek new authors to update it

The editorial group responsible for this previously published document have withdrawn it from publication.

Additives to local anesthetics for peripheral nerve blocks or local anesthesia: a review of the literature

SUMMARY 

A multitude of studies have focused on individual additives to local anesthetics and their effect on quality, onset, duration, spread and selectivity, as well as the potential toxic effects of their use. This review aims to give a broad overview of the current evidence in this developing field, based on beneficial and adverse effects of these drugs. We discuss the limitations of the available data and hope to convey implications and future perspectives for clinicians and researchers alike.

Adjusting the pH of lidocaine for reducing pain on injection

BACKGROUND

Lidocaine administration produces pain due to its acidic pH.

OBJECTIVES

The objective of this review was to determine if adjusting the pH of lidocaine had any effect on pain resulting from non-intravascular injections in adults and children. We tested the hypothesis that adjusting the pH of lidocaine solution to a level closer to the physiologic pH reduces this pain.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, to June 2010); Ovid MEDLINE (1966 to June 2010); EMBASE (1988 to June 2010); LILACS (1982 to June 2010); CINAHL (1982 to June 2010); ISI Web of Science (1999 to June 2010); and abstracts of the meetings of the American Society of Anesthesiologists (ASA). We checked the full articles of selected titles. We did not apply any language restrictions.

SELECTION CRITERIA

We included double-blinded, randomized controlled trials that compared pH-adjusted lidocaine with unadjusted lidocaine. We evaluated pain at the injection site, satisfaction and adverse events. We excluded studies in healthy volunteers.

DATA COLLECTION AND ANALYSIS

We separately analysed parallel-group and crossover trials; trials that evaluated lidocaine with or without epinephrine; and trials with pH-adjusted lidocaine solutions < 7.35 and ≥ 7.35. To explain heterogeneity, we separately analysed studies with a low and higher risk of bias due to the level of allocation concealment; studies that employed a low and a higher volume of injection; and studies that used lidocaine for different types of procedures.

MAIN RESULTS

We included 23 studies of which 10 had a parallel design and 13 were crossover studies. Eight of the 23 studies had moderate to high risk of bias due to the level of allocation concealment.Pain associated with the infiltration of buffered lidocaine was less than the pain associated with infiltration of unbuffered lidocaine in both parallel and crossover trials. In the crossover studies, the difference was -1.98 units (95% confidence interval (CI) -2.62 to -1.34) and in the parallel-group studies it was -0.98 units (95% CI -1.49 to -0.47) on a 0 to 10 scale. The magnitude of the pain decrease associated with buffered lidocaine was larger when the solution contained epinephrine. The risk of bias, volume of injection, and type of procedure failed to explain the heterogeneity of the results.Patients preferred buffered lidocaine (odds ratio 3.01, 95% CI 2.19 to 4.15). No adverse events or toxicity were reported.

AUTHORS' CONCLUSIONS

Increasing the pH of lidocaine decreased pain on injection and augmented patient comfort and satisfaction.

Alkalinization increases penetration of lidocaine across the human cornea

PURPOSE

To test the hypothesis that corneal permeability of lidocaine complies with the principle of nonionic diffusion.

SETTING

Department of Ophthalmology and Institute of Pharmacology, Vienna, Austria.

METHODS

Human corneas, mounted in an in vitro perfusion system under short-circuit conditions, were exposed on the epithelial (tear) side to lidocaine 4% in a buffered solution of pH 5 or pH 7. The endothelial bathing solutions had a constant pH of 7.4. Both solutions were adjusted to an osmolarity of 290 mOsm/L. The lidocaine permeability of the isolated corneas was assessed from the fluxes of 14C-labeled lidocaine across the tissue, measured at 15-minute intervals for 180 minutes, and corrected for the unidirectional fluxes of 3H-polyethylene glycol, a marker for the extracellular pathway. The corneal tissue content of lidocaine was estimated from the time span until the unidirectional lidocaine fluxes across the cornea reached a steady state.

RESULTS

The mean transcorneal fluxes of lidocaine in the steady state (90 to 180 minutes) were 72% higher at pH 7 than at pH 5 (101 mmol/min +/- 37 (SD) versus 59 +/- 34 nmol/min.cornea; P <.002). The corneal content of lidocaine in the steady state was 65% higher at pH 7 than at pH 5 (2.8 +/- 0.9 micromol/cornea versus 1.7 +/- 1.2 micromol/cornea; not significant).

CONCLUSIONS

A shift in solution pH from 5 to 7 significantly increased the corneal permeability of topically applied lidocaine. Alkaline pH-adjustment of topical lidocaine solutions is easy to perform by adding sodium bicarbonate. The main clinical advantages of anesthetic solutions buffered at pH 7 are increased penetration rates, effectiveness, prolonged action time, and a reduction in local irritation and lacrimation.