Early versus delayed dressing removal for surgical wounds

  • Protocol
  • Intervention

Authors


Abstract

This is the protocol for a review and there is no abstract. The objectives are as follows:

To evaluate the benefits and risks of removing a dressing covering a closed surgical incision site up to 48 hours (early dressing removal) and beyond 48 hours (delayed dressing removal) on surgical site infection.

Background

Description of the condition

Most surgical procedures involve a cut in the skin, allowing the surgeon to gain access to the surgical site. At the end of the procedure the incision is closed and in most instances results in a closed surgical wound. This is called primary closure (Garcia-Gubern 2010). The various techniques for wound closure include closure using sutures, staples, adhesive tapes and tissue glue (Ahn 2011; Biancari 2010; Hasan 2009). Primary closure is essential to restore the skin barrier that prevents infection of deeper tissues. However, it is not always possible to maintain clean conditions throughout the surgery, for example, when operating on a contaminated wound (external wounds resulting from trauma) or when operating on tissues that contain contaminated material (e.g. surgery on colon that contains faecal material). In these situations it is sometimes best to delay closure of the wound until the wound develops good granulation tissue and this is called secondary closure (Garcia-Gubern 2010).

Various factors can affect wound healing, such as infection or mechanical strain leading to wound dehiscence, wound infection (currently termed 'surgical site infection') or both. Surgical site infections (SSIs) have been classified and defined as superficial incisional surgical site infections that involve only the skin or subcutaneous tissue around the incision, deep incisional surgical site infections that involve deep soft tissues, such as the fascia and muscles (both occurring within 30 days of procedure, or one year in the case of implants), and organ/space surgical site infections that involve any part of the body (excluding the skin incision, fascia or muscle layers) that is opened or manipulated during the operative procedure (Horan 1992). The incidence of SSI varies according to the classification of surgical wounds. Surgical wounds can be classified in different ways. One accepted classification which has been adopted by the Centers for Disease Prevention and Control (CDC) is to define the wound as clean, clean-contaminated, contaminated, and dirty or infected (Garner 1986). This classification is shown in Appendix 1. The incidence of SSI can vary between 1% and 80% depending upon the types of surgery, the hospital setting (community hospital, tertiary care hospital, etc), the classification of surgical wounds, and the method of skin closure (Biancari 2010; Broex 2009; Garner 1986). It is estimated that the presence of SSI can double the costs of the surgery (Broex 2009).

Description of the intervention

The surgeon covers the surgical wound which has been closed, using either a dressing or adhesive tape (steri strips) or both. Wound dressings are classified in a number of ways based on their function (e.g. occlusive, absorbent), type of material (e.g. hydrocolloid, collagen) and the physical form of dressing (e.g. ointment, film, foam) (Boateng 2008). Some dressings are designed to control the environment for wound healing, for example to donate fluid (hydrogels), maintain hydration (hydrocolloids) or to absorb wound exudates (alginates, foams) (BNF 2011). These dressings can be either transparent (e.g. vapour-permeable films), so that the wound can be monitored without the need for frequent dressing change, or non-transparent (Mepore). Wound dressings are customarily left in place for at least 48 hours (delayed dressing removal).

How the intervention might work

The dressing can act as a physical barrier to protect the wound until the continuity of the skin (epithelialisation) occurs in about 48 hours (Lawrence 1998) and to absorb exudate from the wound, keeping it dry and clean with the aim of avoiding bacterial contamination from the external environment (Hutchinson 1991; Mertz 1985; Ubbink 2008). Another reason for using a dressing is to prevent contamination of the immediate proximity by any wound discharge (Downie 2010). Some studies have found that the moist environment created by some dressings accelerates wound healing (Dyson 1988), although others believe that the moist environment created by the dressing is a disadvantage as excessive exudate can cause maceration of the wound and the surrounding healthy tissue (Cutting 2002). Ideally dressings are chosen to ensure that the wound remains:

  • moist with exudate, but not macerated;

  • free of clinical infection and excessive slough;

  • free of toxic chemicals, particles or fibres;

  • at the optimum temperature for healing;

  • undisturbed by the need for frequent changes;

  • at the optimum pH value.

As wound healing progresses, it may be appropriate to use different types of dressings accordingly (BNF 2011).

Why it is important to do this review

The dressing applied to surgical wounds at the time of surgery can either be removed early, changed regularly or retained until the removal of sutures or strips. This may cause inconvenience to the patient and increase nursing time, with the inevitable increase in associated costs (Chrintz 1989; Dosseh 2008; Merei 2004). In simulated wounds, dressings increase the chance of localised sweating and can reduce moisture evaporation, with the resulting increased dampness potentially acting as a nidus for infection (Gwosdow 1993). Thus, there are some potential disadvantages to delayed dressing removal. There has been no systematic review of early dressing removal (dressing removal before 48 hours after surgery) versus delayed dressing removal (dressing removal after 48 hours after surgery) for surgical wounds.

Objectives

To evaluate the benefits and risks of removing a dressing covering a closed surgical incision site up to 48 hours (early dressing removal) and beyond 48 hours (delayed dressing removal) on surgical site infection.

Methods

Criteria for considering studies for this review

Types of studies

We will include randomised clinical trials (RCTs), irrespective of their use of blinding, language of publication, publication status, date of publication, study setting or sample sizes. We will exclude quasi-randomised studies (where the methods of allocating participants to a treatment are not strictly random, for example, date of birth, hospital record number, alternation), cluster-randomised clinical trials and other study designs.

Types of participants

People, of any age and sex, undergoing a surgical procedure (major, minor or day-case procedure) who have their wound closed, irrespective of the material and method used for the primary closure and the location of the wound. We will exclude trials which include people with contaminated or dirty (infected) wounds. For eligible studies that have mixed populations (i.e. a mix of people with clean and dirty wounds), we will extract the data for clean and clean-contaminated wounds if available separately. If this information is not available, we will attempt to contact the study authors to obtain the data for these specific subgroups. If we still are unable to obtain this information, we will exclude the study.

Types of interventions

Wound dressings when used are almost always applied immediately after surgery. We will include trials comparing the removal of the wound dressing up to 48 hours after surgery (early group) with continued dressing of the wound beyond 48 hours (delayed group). There will be no differentiation in the type of dressing and whether the dressing applied at the time of surgery is retained or changed. Co-interventions will be allowed (e.g. antibiotics, wound drainage, etc.), provided that they are used equally in all groups.

Types of outcome measures

Primary outcomes
  1. Surgical site infection within 30 days of operation. We will attempt to use the definition of surgical site infection that matches the standard definition of surgical site infection described by Horan 1992. Otherwise, we will accept the definitions by the authors of the report.

    1. Superficial.

    2. Deep.

  2. Wound dehiscence within 30 days of operation. Postoperative wound dehiscence refers to wound disruptions resulting from poor wound healing caused by various factors such as type of incision, infection, anaemia, diabetes, ascorbic acid deficiency, etc. (Keill 1973). They are classified as:

    1. superficial (dehiscence involving skin and subcutaneous tissue);

    2. deep (burst abdomen).

  3. Other serious adverse events within 30 days of operation, defined as any event that would increase mortality; is life-threatening; requires inpatient hospitalisation or prolongation of existing hospitalisation; results in a persistent or significant disability/incapacity, or any important medical event, which might have jeopardised the patient or requires intervention to prevent it (ICH-GCP 1996). We recognise that the main intended role of dressing is to prevent wound related complications but want to assess the impact of dressing in the overall context of the operation.

Secondary outcomes
  1. Quality of life at maximal follow-up (however defined by authors).

  2. Length of hospital stay at maximal follow-up.

  3. Time taken to return to work.

  4. Costs at maximal follow-up (however reported by authors).

Search methods for identification of studies

Electronic searches

We will search the following electronic databases to identify reports of relevant randomised clinical trials:

  • Cochrane Wounds Group Specialised Register;

  • The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library latest issue);

  • Ovid MEDLINE (1948 to present);

  • Ovid EMBASE (1980 to present);

  • EBSCO CINAHL (1982 to present)

We will adapt this strategy to search Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL. We will combine the Ovid MEDLINE search with the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity- and precision-maximising version (2008 revision) (Lefebvre 2011). We will combine the EMBASE and CINAHL searches with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN 2011). We will not restrict studies with respect to language, date of publication or study setting.

We will search the metaRegister of Controlled Trials (mRCT) (http://www.controlled-trials.com/mrct/) and ICTRP (International Clinical Trials Registry Platform) portal maintained by World Health Organization (http://apps.who.int/trialsearch/). The meta-register includes the ISRCTN Register and NIH ClinicalTrials.gov Register among other registers. The ICTRP portal includes these trial registers along with trial registry data from a number of countries.

We will use the following provisional search strategy in The Cochrane Central Register of Controlled Trials (CENTRAL):

#1 MeSH descriptor Bandages explode all trees
#2 (dressing* or hydrocolloid* or alginate* or hydrogel* or "foam" or
"bead" or "film" or "films" or tulle or gauze or non-adherent or "non adherent" or silver or honey or matrix):ti,ab,kw
#3 (#1 OR #2)
#4 MeSH descriptor Surgical Wound Infection explode all trees
#5 MeSH descriptor Surgical Wound Dehiscence explode all trees
#6 surg* NEAR/5 infect*:ti,ab,kw
#7 surg* NEAR/5 wound*:ti,ab,kw
#8 surg* NEAR/5 site*:ti,ab,kw
#9 surg* NEAR/5 incision*:ti,ab,kw
#10 surg* NEAR/5 dehiscen*:ti,ab,kw
#11 wound* NEAR/5 infect*:ti,ab,kw
#12 wound* NEAR/5 dehiscen*: ti,ab,kw
#13 (#4 OR #5 OR #6 OR #7 OR #8 OR #9 OR #10 OR #11 OR #12)
#14 (#3 AND #13)

Searching other resources

We will search the references of included trials to identify further relevant trials. We will contact the suture manufacturers such as Johnson and Johnson, 3M, etc about any trials that they are aware of.

Data collection and analysis

We will perform the systematic review following the instructions given in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011a).

Selection of studies

We will not apply any language or publication status restrictions. Two review authors (RR and KG) will independently sift through the search results and identify the references for retrieval in full text. We will seek the full text for any reference that is considered likely to meet the inclusion criteria. Final decisions on inclusion or exclusion of studies will be based on reading the full text. We will also list the excluded studies with reasons for exclusion.

Data extraction and management

Two review authors (RR and KG) will extract the following data independently.

  1. Year and language of publication.

  2. Country of conduct of the trial.

  3. Year of conduct of the trial.

  4. Inclusion and exclusion criteria.

  5. Sample size.

  6. Anatomical location of wound.

  7. Type of operation (primary closure versus secondary closure; actual operation; clean or clean contaminated wound).

  8. Type of wound closure.

  9. Type of dressing (occlusive versus non-occlusive; moist versus dry; manufacturer's name; type of material).

  10. Co-morbidities in the patient (for example, diabetes).

  11. Antibiotics used.

  12. Outcome data for primary and secondary outcomes (by group).

  13. Duration of follow-up.

  14. Number of withdrawals (by group).

  15. Assessment of risk of bias (as described below).

Where multiple reports exist for a trial, we will examine all the reports for information. We will seek clarification for any unclear or missing information by contacting the authors of the individual trials. If there is any doubt about whether the trials share the same participants - completely or partially (by identifying common authors and centres) - we will contact the study authors of the trials to check whether the trial report has been duplicated. We will resolve any differences in opinion through discussion amongst the review authors.

Assessment of risk of bias in included studies

We will follow the instructions given in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011b). According to empirical evidence (Kjaergard 2001; Moher 1998; Schulz 1995; Wood 2008), we will assess the risk of bias of included trials based on the following risk of bias domains:

Sequence generation
  • Low risk of bias: the method used is either adequate (e.g. computer-generated random numbers, table of random numbers) or unlikely to introduce confounding.

  • Unclear risk of bias: there is insufficient information to assess whether the method used is likely to introduce confounding.

  • High risk of bias (the method used is improper and likely to introduce confounding (e.g. quasi-randomised studies). We will exclude such studies.

Allocation concealment
  • Low risk of bias: (the method used is unlikely to induce bias on the final observed effect (e.g. central allocation).

  • Unclear risk of bias: there is insufficient information to assess whether the method used is likely to induce bias on the estimate of effect.

  • High risk of bias: the method used is likely to induce bias on the final observed effect (e.g. open random allocation schedule).

Blinding of participants and personnel

It is impossible to blind the participants. So, we will classify patient-reported outcomes such as quality of life at high risk of bias as this is a subjective outcome and a patient's belief may influence the reporting of quality of life. However, it is possible to blind the healthcare providers. So, we will consider outcomes not reported by patients as follows.

  • Low risk of bias: blinding was performed adequately, or the outcome measurement is not likely to be influenced by lack of blinding.

  • Unclear risk of bias: there is insufficient information to assess whether the type of blinding used is likely to induce bias on the estimate of effect.

  • High risk of bias: no blinding or incomplete blinding, and the outcome or the outcome measurement is likely to be influenced by lack of blinding.

Blinding of outcome assessors
  • Low risk of bias: blinding was performed adequately, or the outcome measurement is not likely to be influenced by lack of blinding.

  • Unclear risk of bias: there is insufficient information to assess whether the type of blinding used is likely to induce bias on the estimate of effect.

  • High risk of bias: no blinding or incomplete blinding, and the outcome or the outcome measurement is likely to be influenced by lack of blinding.

Incomplete outcome data
  • Low risk of bias: the underlying reasons for missingness are unlikely to make treatment effects departure from plausible values, or proper methods have been employed to handle missing data.

  • Unclear risk of bias: there is insufficient information to assess whether the missing data mechanism in combination with the method used to handle missing data is likely to induce bias on the estimate of effect.

  • High risk of bias: the crude estimate of effects will clearly be biased due to the underlying reasons for missingness, and the methods used to handle missing data are unsatisfactory (e.g. complete case estimate).

Selective outcome reporting
  • Low risk of bias: the trial protocol is available and all of the trial's pre-specified outcomes that are of interest in the review have been reported or similar; if the trial protocol is not available, all the primary outcomes in this review are reported.

  • Unclear risk of bias: there is insufficient information to assess whether the magnitude and direction of the observed effect is related to selective outcome reporting.

  • High risk of bias: not all of the trial's pre-specified primary outcomes have been reported or similar.

We will consider trials which are classified as low risk of bias in all the above domains as low bias-risk trials. We will consider the other trials to be high bias-risk trials.

Measures of treatment effect

For dichotomous variables, we will calculate the risk ratio (RR) with 95% confidence intervals (CI). For continuous variables, we will calculate the mean difference (MD) with 95% CI for outcomes that can be quantified, such as hospital stay and return to work, and the standardised mean difference (SMD) with 95% CI for outcomes such as quality of life where different assessment scales may be used in different studies. We will also report the results of risk difference (RD) if they are different from those of risk ratio. This is because the risk difference takes trials with zero events in both groups into account while risk ratio does not include such trials in the meta-analysis.

Unit of analysis issues

We will include simple RCTs of parallel design. The individual patient will be the unit of analysis. We do not anticipate cluster-RCTs. If we identify cluster-RCTs, we will include them in the quantitative analysis if the treatment effect is reported after adjusting for the cluster effect. We will exclude trials of other designs such as cross-over trials.

Dealing with missing data

We will perform an intention-to-treat analysis whenever possible (Newell 1992). We will impute data for binary outcomes using various scenarios such as good outcome analysis, bad outcome analysis, best-case scenario and worst-case scenario (Gurusamy 2009).

For continuous outcomes, we will use available-case analysis. We will impute the standard deviation from P values according to the instructions given in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011c), and we will use the median for the meta-analysis when the mean is not available. If it is not possible to calculate the standard deviation from the P value or the confidence intervals, we will impute the standard deviation as the highest standard deviation in the other trials included under that outcome, fully recognising that this form of imputation will decrease the weight of the study for calculation of mean differences and bias the effect estimate to no effect in case of standardised mean difference (Higgins 2011d).

Assessment of heterogeneity

We will explore heterogeneity by Chi2 test with the threshold for statistical significance set at P value 0.10, and measure the quantity of heterogeneity by the I2 statistic (Higgins 2002).

Thresholds for the interpretation of the I2 statistic can be misleading. A rough guide to interpretation is as follows (Deeks 2011).

  • 0% to 40%: might not be important.

  • 30% to 60%: may represent moderate heterogeneity.

  • 50% to 90%: may represent substantial heterogeneity.

  • 75% to 100%: considerable heterogeneity.

Assessment of reporting biases

We will explore reporting bias using visual asymmetry on the funnel plot (Egger 1997; Macaskill 2001). We will perform linear regression as described by Egger 1997 to determine funnel plot asymmetry. We will also explore reporting bias from selective outcome reporting of the trials.

Data synthesis

We will perform the meta-analysis using the software RevMan 5 (RevMan 2011) and following the recommendations of The Cochrane Collaboration (Deeks 2011). We will use both random-effects model (DerSimonian 1986) and fixed-effect model (DeMets 1987) of meta-analysis. In case of discrepancy between the two models identified from the pooled estimates and their confidence intervals, we will report both results; otherwise we will report the results of the fixed-effect model. With regards to dichotomous outcomes, risk ratio calculations do not include trials in which no events occurred in either group in the meta-analysis, whereas risk difference calculations do. We will report the risk difference (RD) if the results using this association measure are different from risk ratio in terms of statistical significance. However, risk ratio is the measure that we will use to arrive at conclusions, since risk ratios perform better when there are differences in the control event rate (proportion of patients who develop the event in the control).

Summary of findings

We will present the 'Summary of findings' table for all the primary and secondary outcomes whenever possible (Schünemann 2011).

Subgroup analysis and investigation of heterogeneity

We hope to perform the following subgroup analyses in the presence of adequate number of trials.

  • Trials with low risk of bias (considered to be at low risk of bias in all the risk of bias domains) compared to trials with high or unclear risk of bias.

  • Based on the type of dressing (dry, moist, occlusive, absorbent) (some types of dressings may be useful while other types of dressings may not be useful).

  • Based on type of surgery (trunk versus extremities) (wound healing rates may be different in the trunk and extremities, particularly in patients who have peripheral vascular diseases).

  • Based on type of wound closure (sutures versus staples versus adhesive tapes). Dressings may be useful in some types of wound closure while they may not be useful in other forms of dressings.

  • Based on degree of contamination (clean versus clean-contaminated). Dressings may be useful in clean-contaminated wounds by absorbing any exudate while they may not be useful in clean wounds.

  • Antibiotic treatment up to 48 hours of surgery versus greater than 48 hours (i.e. continuation of antibiotic after removal of dressing in the early group). Antibiotics may eradicate bacteria even if the wound gets contaminated, thereby preventing infection.

We will use a P value of less than 0.05 for the Chi2 test for subgroup differences to identify the differences between subgroups.

Sensitivity analysis

We will perform sensitivity analysis by imputing data for dichotomous outcomes using various scenarios including good outcome analysis, bad outcome analysis, best-case scenario and worst-case scenario (Gurusamy 2009). We will perform sensitivity analysis by excluding the trials in which the mean and the standard deviation were imputed.

Acknowledgements

We acknowledge the help and support of the Cochrane Wounds Group. The authors would also like to thank the following editors and peer referees who provided comments to improve the protocol: Susan O'Meara (editor), Evangelos Kontopantelis and Iain McCallum and to Jenny Bellorini for copy editing the protocol.

Appendices

Appendix 1. Classification of surgical wounds

Clean wound

  • Uninfected operative wounds

  • No inflammation is encountered

  • Respiratory, alimentary, genital or uninfected urinary tracts are not entered

  • Primarily closed

Clean-contaminated wound

  • Respiratory, alimentary, genital or urinary tract is entered under controlled conditions

  • Without unusual contamination

  • No evidence of infection or major break in sterile technique is encountered

Contaminated wound

  • Open, fresh accidental wounds or operations with major breaks in sterile technique or gross spillage from the gastrointestinal tract or incisions in which acute, non-purulent inflammation is encountered

Dirty wound

  • Old traumatic wounds with retained devitalised tissue or those that involve existing clinical infection or perforated viscera (i.e. the organisms causing postoperative infection were present in the operative field before the operation)

History

Protocol first published: Issue 12, 2012

Contributions of authors

Rajarajan Ramamoorthy developed the protocol, completed the first draft of the protocol, performed part of the writing or editing, made an intellectual contribution and approved the final version prior to submission. 
Brian Davidson conceived the review question, secured funding, made an intellectual contribution, advised on the protocol and approved the final version prior to submission. 
Kurinchi Gurusamy conceived the review question, developed the protocol, coordinated the protocol development, secured funding, performed part of the writing or editing of the protocol, made an intellectual contribution, advised on the protocol, approved the final version prior to submission and is guarantor.

Contributions of editorial base:

Nicky Cullum: edited the protocol; advised on methodology, interpretation and protocol content. Approved the final protocol prior to submission.
Sally Bell-Syer: coordinated the editorial process. Advised on methodology, interpretation and content. Edited and copy edited the protocol.
Ruth Foxlee: designed the search strategy and edited the search methods section.

Declarations of interest

None known.

Sources of support

Internal sources

  • No sources of support supplied

External sources

  • National Institute for Health Research (NIHR - UK Government organisation for health research), UK.

    NIHR provides financial support for K Gurusamy for completing the review

  • NIHR / Department of Health (England), (Cochrane Wounds Group), UK.

Ancillary