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COCHRANE'S SYSTEMATIC REVIEW: SURGICAL FACE MASKS

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VOL: 98, ISSUE: 38, PAGE NO: 56

Allyson Lipp, principal lecturer, University of Glamorgan

Kathryn Little, lecturer, University of Hull

Lipp, A., Edwards, P. (2002)Disposable Surgical Face Masks for Preventing Surgical Wound Infection in Clean Surgery. Cochrane Library, Update Software. http:/cochrane.org.

Lipp, A., Edwards, P. (2002)Disposable Surgical Face Masks for Preventing Surgical Wound Infection in Clean Surgery. Cochrane Library, Update Software. http:/cochrane.org.

Objectives
To identify and review all randomised controlled trials evaluating disposable surgical face masks worn by the surgical team during clean surgery to prevent postoperative surgical wound infection.

Search strategy
All relevant publications about disposable surgical face masks were sought through the Specialised Trials Register of the Cochrane Wounds Group (March 2001). Manufacturers of disposable surgical masks and professional organisations were contacted for details of unpublished and ongoing studies.

Selection criteria
Randomised controlled trials and quasi-randomised controlled trials comparing the use of disposable surgical masks with the use of no mask were included. Trials performed under laboratory conditions, those measuring wound contamination or air contamination via settle plates only were not included.

Main results
Ninety-seven papers were retrieved. However, only two randomised controlled trials met the criteria for inclusion. These involved a total of 1,453 patients. In a small trial there was a trend towards masks being associated with fewer infections, whereas in a large trial there was no difference in infection rates between the masked and unmasked group.

Trial composition
Chamberlain and Houang (1984) performed a quasi-randomised controlled trial in the UK using alternate operating lists to dictate whether the operating team would be masked or unmasked. The length of follow-up for potential wound infection was until discharge. The outcome assessors were blinded to the trial set-up and no patient drop-outs were recorded.

Tunevall (1991) completed a quasi-randomised controlled trial in Sweden in which weeks of surgery were determined as masked or unmasked, according to a random list. The length of follow-up for potential wound infection was until after discharge. A power calculation was performed and showed that at least 3,000 patients were needed for an adequate sample size. Blinding of outcome assessors was not made clear in the study, and no patient drop-outs were recorded.

Data collection and analysis
In Chamberlain and Houang's study (1984) the participants were 41 female patients undergoing surgery, and data was collected over seven weeks; 24 patients were undergoing clean surgery and 17 non-clean surgery. The inclusion criteria for the study were gynaecology surgery and there were no specific exclusion criteria. No baseline comparability was reported.

In Tunevall's study (1991) 3,088 patients underwent general, vascular, breast, acute and cold surgery and this data was collected over a period of 115 weeks. Non-clean surgery was performed on 1,659 and clean surgery was performed on 1,429 patients. Inclusion criteria were operation through intact skin and primary closure. Exclusion criteria were when patients were not informed, or consent was not given. Also excluded were outpatients, orthopaedics, urology, anal surgery, insertion of synthetic grafts or patients with haematologic disease. The baseline comparability was similar for age, acute and cold surgery.

Infection outcome measures
In Chamberlain and Houang's study (1984) the authors defined wound infection as serious enough to warrant antibiotics in two of the cases and via high vaginal swab in the third. In the group of patients whose operating staff wore masks, none out of the 14 patients had wound infections, whereas three out of the 10 patients whose operating staff did not wear masks had wound infections. This study was discontinued due to the three surgical wound infections in the unmasked group, although the authors admitted that bacterial link was not causal.

Tunevall (1991) defined wound infection as visible pus and/or cellulitis without pus requiring debridement, drainage and/or antibiotics. In this trial 13 out of 706 clean-case patients whose operating staff wore masks had a wound infection and 10 out of 723 clean cases of patients whose operating staff did not wear masks had a wound infection. All patients received two to three body washes with chlor-hexidine before elective surgery, and in most acute cases at least one body wash was given.

Combining the results of the two studies shows that 13 out of 720 in the masked group and 13 out of 733 in the non-masked group acquired a wound infection. These results are not statistically or clinically significant and the clinical and statistical heterogeneity prevented further scrutiny via meta-analysis of the studies.

Reviewers' conclusions
From the limited results it is unclear whether wearing surgical face masks results in any harm or benefit to the patient undergoing clean surgery. Plowman et al (2000) estimated that a patient with a surgical wound infection on average requires an additional hospital stay of 6.5 days and that hospital costs are doubled. On this premise further research is advocated.

ICNA HAND DECONTAMINATION GUIDELINES
ICNA (2002)Hand Decontamination Guidelines. ICNA/Fitwise, Drumcross Hall, Bathgate EH48 4JT Tel: 01506 811077.

£5 members, £10 non-members

The aim of these guidelines is to provide an important teaching resource for all health care workers. The booklet is divided into six sections in which the case for handwashing is presented. Each section is clearly laid out and punctuated with appropriate headings. Key points are presented in shaded boxes and illustrations are included where appropriate. At the end of each section a summary of the key points is made and references appropriate to each subject are included.

Context for the guidelines is presented in section one. The difficulty in demonstrating where hands have been involved in transmission of infection is acknowledged, although it is claimed that there is a 'considerable' amount of circumstantial evidence regarding their role. Unfortunately only two dated references are offered in support, which might disappoint some readers who would look to this booklet to provide more evidence for their teaching sessions.

Further sections look at the microbiology of the hands and explain the differences between transient and resident flora and why hand-washing is effective in removing the former. The aims of hand decontamination and when and how to wash your hands includes risk assessment as the key to getting it right.

The latter sections address skin care, with important points on the use of hand creams and gloves and the key issue of improving hand decontamination technique and compliance. Well documented reasons for non-compliance are summarised and strategies to obtain improvements and therefore reduce risk of health care-acquired infections are suggested. Education is acknowledged as the key to success, and improving the quality and quantity of education is the challenge. Others that could impact on the application of the procedure are sanctions and rewards and avoiding under-staffing and excessive workloads.

Overall, the content of the booklet is not that different from what has gone before. There is greater emphasis on the issues of quality and clinical governance and the value of risk assessment. It will provide a valuable reference and teaching guide for all health care workers. The cost to non-members of the ICNA may be prohibitive and limit its availability which is unfortunate. Arguably such important information should be freely available.

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