Surgery on fingers is a common procedure in emergency and day care surgery (Angermann 1993). Adrenaline (any dilutions) combined with lidocaine can prolong digital nerve block and provide a bloodless operating field. Extended postoperative pain relief can reduce the need for analgesics and can facilitate hand rehabilitation. Conventionally, adrenaline is avoided at anatomical sites with end arteries such as digits, penis and pinna because of concerns about arterial spasm, ischaemia and gangrene distal to the site of drug infiltration (Wilhelmi 2001). End arteries, which are also known as terminal arteries , are the only supply of blood to a particular body part. Studies have demonstrated the safety of adrenaline with lidocaine for digital nerve blocks and for prolonged duration of anaesthesia (Thomson 2006).
Description of the condition
Finger injuries commonly result from industrial, domiciliary and road traffic accidents (Angermann 1993). Most of these injuries are treated in emergency departments or in day care centres. Digital nerve block with lidocaine is a convenient and successful technique with low complication rates and high patient acceptance (Thomson 2006). The only limitation is that the duration of nerve block with lidocaine is short, and additional administration may be required during surgery.
Description of the intervention
Adding adrenaline to lidocaine significantly increases the duration of anaesthesia (Sonohata 2012) because adrenaline causes constriction of the blood vessels and thereby delays absorption of the drug from the site of administration.
How the intervention might work
Adrenaline causes vasoconstriction of surrounding vessels and restricts absorption of lidocaine, thereby increasing the duration of anaesthesia (Wilhelmi 1998). The vasoconstrictive effect provides a bloodless operating field, which is an added benefit (Lalonde 2005; Wilhelmi 2001) .
Why it is important to do this review
Combining adrenaline with lidocaine for regional or local nerve blocks significantly increases the duration of anaesthesia. When adrenaline is used as local infiltration anaesthesia, its vasoconstrictive effect is an added benefit, as this provides a bloodless operating field. Adrenaline is not used conventionally for digital nerve block because of the risk of digital ischaemia from vasoconstriction of the end arteries (Wilhelmi 2001). This systematic review will gather available evidence for the safety of use of adrenaline (any dilutions) with lidocaine (any dilutions) for digital nerve blocks (fingers and toes) and will compare the duration of this combination anaesthesia with that of lidocaine alone.
To assess the safety of use of adrenaline (any dilutions) combined with lidocaine (any dilutions) for digital nerve blocks (fingers and toes).
Criteria for considering studies for this review
Types of studies
We will include randomized controlled trials (RCTs) that compare the use of lidocaine with and without adrenaline in participants undergoing surgery for digits (fingers and toes). We will exclude quasi-randomized, cluster randomized and cross-over trials.
We will exclude studies in which any other adjuvant is used along with lidocaine in the same participant. We will also exclude studies in which any other anaesthetic technique is used along with lidocaine in the same participant.
Types of participants
We will include in our review all adult (age > 18 years) and paediatric (age < 18 years) participants of either gender undergoing surgery of digits (fingers and toes) under nerve blocks using lidocaine with adrenaline.
We will exclude neonates from our review.
Types of interventions
Our experimental group will include participants receiving peripheral nerve blocks with a lidocaine and adrenaline mixture.
Our control group will include participants receiving peripheral nerve blocks with lidocaine only.
Types of outcome measures
- Duration of anaesthesia reported in minutes/hours.
- Adverse outcome such as ischaemia distal to the injection site reported as a dichotomous outcome.
- Cost analysis.
- Duration of postoperative pain relief reported in minutes/hours.
- Reduced bleeding during surgery (reported as a dichotomous outcome, yes or no/increased or decreased bleeding), as suggested by the operating surgeon.
Outcomes will not form part of the study eligibility assessment, so that studies meeting the participant, intervention and comparison criteria will be included in the review even if they report no relevant outcomes.
Search methods for identification of studies
We will search the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, latest issue; see Appendix 1), MEDLINE via Ovid SP (1966 to date; see Appendix 2) and EMBASE via Ovid SP (1980 to date; see Appendix 3). The MEDLINE and EMBASE search strategy is combined with the highly sensitive Cochrane search filter in identifying RCTs (Lefebvre 2011).
We apply no language restrictions.
Searching other resources
We will search for relevant ongoing trials on specific Websites such as:
Data collection and analysis
Selection of studies
Using the results of the above searches, we will screen all titles and abstracts for eligibility. Two review authors (SR and HP) will independently perform this screening. We will obtain and assess for relevance the full articles of all potentially eligible RCTs based on the preplanned checklist. Each review author will document the reason for exclusion of each excluded trial. We will resolve any disagreement between the two review authors by discussion and consensus. We will compile a list of all eligible trials.
Data extraction and management
Two review authors (SR and HP) will independently extract data and assess trial quality using a standardized form (see Appendix 4). In cases for which additional information is required, SR will contact the first author of the relevant trial.
Assessment of risk of bias in included studies
Two review authors will independently assess the methodological quality of eligible trials (SR and HP). We will perform this assessment as suggested in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We will judge the quality of the studies on the basis of the following quality domains:
- Random sequence generation.
- Allocation concealment.
- Blinding and outcome.
- Incomplete outcome reporting.
- Publication and any other bias.
We will consider a trial as having a low risk of bias if all domains are assessed as adequate. We will consider a trial as having a high risk of bias if one or more domain is assessed as inadequate or unclear.
We will include a 'Risk of bias' table as part of the 'Table of characteristics of included studies' and a 'Risk of bias summary' figure, which will detail all of the judgements made for all studies included in the review.
Measures of treatment effect
We will undertake an analysis using RevMan 5.1 software. We will use risk ratio (RR) to measure treatment effect for proportions (dichotomous outcomes) among primary and secondary outcomes and adverse effects. We will convert continuous data to the mean difference (MD) using the inverse variance method, and an overall MD will be calculated. We will use a fixed-effect model when no evidence of significant heterogeneity is noted between studies, and a random-effects model when heterogeneity is likely (DerSimonian 1986). As an estimate of the statistical significance of a difference between experimental and control interventions, we will calculate RR and MD between groups along with 95% confidence intervals (CIs). A statistically significant difference between intervention and control groups will be assumed if the 95% CI does not include the value of no differential effect.
Unit of analysis issues
We will include in our review only RCTs with a parallel group design. The nature of the intervention here suggests that unit of analysis issues, such as those associated with cluster randomization, are unlikely to arise.
Dealing with missing data
We will perform quantitative analysis on an intention-to-treat (ITT) basis and will contact the authors to obtain missing data. We will analyse missing data, if any, by imputation using a best-case and worst-case scenario method. If we find insufficient data, the potential impact of the missing data will be considered in the interpretation of results.
Assessment of heterogeneity
We will not perform meta-analysis if we suspect important clinical heterogeneity on examination of the included trials. We will use the Q statistic to test statistical heterogeneity between trials and will consider P ≤ 0.05 as indicating significant heterogeneity; the I
Assessment of reporting biases
We will assess publication bias and small study effect in a qualitative manner, using a funnel plot. We will test for funnel plot asymmetry if more than 10 studies are included in the meta-analysis.
We will quantitatively review the included data and will combine data by intervention, outcome and population using The Cochrane Collaboration statistical software (RevMan 5.1). We will synthesize the data only in the absence of important clinical or statistical heterogeneity, and we will express pooled estimates of the mean difference (MD) for continuous variables and risk ratio (RR) for proportions, as described above.
Subgroup analysis and investigation of heterogeneity
Where appropriate, when clinical or statistical (I
We will perform sensitivity analysis to explore the consistency of effect size measures in trials with low risk of bias versus high risk of bias and to investigate the impact of missing data using the imputation method described above.
Summary of findings
We will use the principles of the GRADE system (Guyatt 2008) to assess the quality of the body of evidence associated with specific outcomes (duration of anaesthesia, an adverse outcome such as ischaemia distal to the injected site, cost analysis, duration of postoperative pain relief and reduced bleeding during surgery) in our review and will construct a 'summary of findings' (SoF) table using the GRADE software. The GRADE approach involves appraising the quality of a body of evidence based on the extent to which one can be confident that an estimate of effect or association reflects the item being assessed. The quality of a body of evidence is determined by consideration of within-study risk of bias (methodological quality), directness of the evidence, heterogeneity of the data, precision of effect estimates and risk of publication bias.
We would like to thank Jane Cracknell (Managing Editor of the Cochrane Anaesthesia Review Group (CARG)) for guiding us through this protocol and Karen Hovhannisyan (CARG Trials Search Co-ordinator) for preparing our search strategy. We would like to thank Ronan O'Sullivan (Content Editor), Cathal Walsh (Statistical Editor) and Saeed Chowdhry, Don Lalonde and Vaughan Thomas (our peer reviewers) for their help and editorial advice during the preparation of this protocol for a systematic review.
Appendix 1. CENTRAL search strategy
#1 MeSH descriptor: [Lidocaine] explode all trees
#2 MeSH descriptor: [Epinephrine] explode all trees
#3 #1 and #2
#4 ((adrenalin* or epinephrine*) and lidocain*)
#5 #3 or #4
#6 MeSH descriptor: [Nerve Block] explode all trees
#7 ((nerve block* or injur*) near (digit* or finger*))
#8 #6 or #7
#9 #5 and #8
Appendix 2. OVID MEDLINE search strategy
1. (exp Epinephrine/ and exp Lidocaine/) or ((adrenalin* or epinephrine*) and lidocain*).af.
2. exp Nerve Block/ or ((nerve block* or injur*) adj5 (digit* or finger*)).mp.
3. 1 and 2
4. ((randomized controlled trial or controlled clinical trial).pt. or randomized.ab. or placebo.ab. or drug therapy.fs. or randomly.ab. or trial.ab. or groups.ab.) not (animals not (humans and animals)).sh.
5. 3 and 4
Appendix 3. EMBASE (Ovid SP) search strategy
1. (exp adrenalin/ and exp lidocaine/) or exp adrenalin plus lidocaine/ or ((adrenalin* or epinephrine*) and lidocain*).af.
2. exp nerve block/ or ((nerve block* or injur*) adj5 (digit* or finger*)).mp.
3. 1 and 2
4. (randomized-controlled-trial/ or randomization/ or controlled-study/ or multicenter-study/ or phase-3-clinical-trial/ or phase-4-clinical-trial/ or double-blind-procedure/ or single-blind-procedure/ or (random* or cross?over* or multicenter* or factorial* or placebo* or volunteer*).mp. or ((singl* or doubl* or trebl* or tripl*) adj3 (blind* or mask*)).ti,ab. or (latin adj square).mp.) not (animals not (humans and animals)).sh.
5. 3 and 4
Appendix 4. Data extraction form
1. General information
2. Study eligibility
DO NOT PROCEED IF STUDY EXCLUDED FROM REVIEW
3. Population and setting
5. Risk of bias assessment
See Chapter 8 of The Cochrane Handbook for Systematic Reviews of Inteventions.
Provide overall data and, if available, comparative data for each intervention or comparison group.
7. Intervention groups
Copy and paste table for each intervention and comparison group.
Copy and paste table for each outcome.
Outcome 1. Duration of anaesthesia
Outcome 2. Adverse outcomes
Outcome 3. Cost analysis
Outcome 4. Duration of postoperative pain relief
Outcome 5. Reduced bleeding during surgery
Copy and paste the appropriate table for each outcome, including additional tables for each time point and subgroup as required.
Dichotomous outcome 1. Adverse outcomes
Dichotomous outcome 2. Reduced bleeding during surgery
Continuous outcome 1. Duration of anaesthesia
Continuous outcome 2. Cost analysis
Continuous outcome 3. Duration of postoperative pain relief
11. Other information
Contributions of authors
Conceiving the review: Santosh Rath (SR)
Co-ordinating the review: Hemanshu Prabhakar (HP), SR
Undertaking manual searches: HP, SR
Screening search results: HP, SR
Organizing retrieval of papers: HP, SR
Screening retrieved papers against inclusion criteria: HP, SR
Appraising quality of papers: HP, SR
Abstracting data from papers: HP, SR
Writing to authors of papers for additional information: HP
Providing additional data about papers: HP
Obtaining and screening data on unpublished studies: HP
Providing data management for the review: HP, SR
Entering data into Review Manager (RevMan 5.1): HP, SR
Interpreting RevMan statistical data: HP, Mani Kalaivani (MK)
Performing other statistical analyses not using RevMan: MK
Interpreting data: HP, MK
Making statistical inferences: MK
Writing the review: HP
Securing funding for the review: not applicable
Performing previous work that served as the foundation of the present study: not applicable
Serving as guarantor for the review (one review author): HP
Taking responsibility for reading and checking the review before submission: HP, SR
Declarations of interest
Hemanshu Prabhakar: none known
Santosh Rath: none known
Mani Kalaivani: none known
Sources of support
- All India Institute of Medical Sciences, New Delhi, India.
- No sources of support supplied