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The evidence base for using preoperative antiseptics

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When questioning whether a practice is based on evidence, it is worth thinking the unthinkable. In the context of this article it means asking if preoperative preparation is really necessary.

Abstract

VOL: 101, ISSUE: 50, PAGE NO: 26

Allyson Lipp, PHD, MSc, MA, RN, RNT, is principal lecturer, School of Care Sciences, University of Glamorgan, Pontypridd

Preoperative skin preparation has progressed since patients were scrubbed for a number of minutes on the operating table and then had sterile towels sutured to their skin (Gilliam and Nelson, 1990). Progress is manifest by the application today of an antiseptic using a sterile technique and disposable drapes, but this does not necessarily mean greater effectiveness.

A UK economic analysis found that the costs of surgical wound infection could be assigned to three parties: the hospital, the patient and the community (Reilly et al, 2001). For their study, audit data was collected over a three-year period on 2,202 patients who had had clean elective surgery. A full-time audit nurse provided robust feedback to the operating team during the audit. The results revealed a reduction in infection rates. Nevertheless, 220 patients developed surgical wound infections, at a cost of £90,000. Although the use of preoperative antiseptics is often cited as one of the major lines of defence in tackling surgical wound infection, the evidence base for practising the procedure requires thorough investigation.

Is antisepsis worthwhile?

In a seminal study on healthy staff and patients who were not undergoing surgery, the skin of one group was treated with water alone and another had no treatment (Davies et al, 1978). The high bacterial counts on the skin of both groups suggested antisepsis of some description would be more effective than none. Many other studies on preoperative antisepsis are also limited to laboratory experiments measuring the outcome of contamination rather than patient infection (Traore et al, 2000; Jeng and Severin, 1998). This is acceptable providing the results of studies of healthy individuals are not applied to patients with infection.

In a laboratory experiment using healthy volunteers, Gauthier et al (1993) questioned whether the procedure could become clean rather than sterile, and whether this would have any advantages such as cost and time savings. Caution must be signalled because of the small study size and its taking place in a laboratory, but the researchers found a clean preparation kit as effective as a sterile one. However, there were no time savings and little difference in cost.

Laboratory studies are of interest, but generating evidence relating to surgical wound infection provides a more robust base upon which to establish practice.

Expert opinion, or the view of a theatre team, is often the rationale for choice of antiseptic. However, this is the least credible level in a hierarchy of evidence in which systematic reviews are most highly esteemed (Lipp, 2003). Two colleagues and I therefore carried out a systematic review to establish which antiseptics were most effective (Edwards et al, 2004). A literature search of published and unpublished material revealed 154 references, 114 of which were retrieved for further examination. Of the 18 trials found, six were included in the review, totalling 1,458 patients undergoing clean surgery.

Results

Three of the six studies compared types of iodine. Roberts et al (1995) compared iodine as a one-step application of iodophor and a scrub of iodophor followed by iodophor paint in 200 patients. There was no statistically significant difference in rates of surgical wound infection. Alexander et al (1985) compared two per cent iodine in 90 per cent alcohol with a povidone iodine soap followed by two applications of povidone iodine paint. Only one patient in each group developed a postoperative wound infection. The study had too few participants to be statistically significant and no discernible difference in wound infection was found between the methods of skin preparation.

Segal and Anderson (2002) compared four procedures: povidone iodine paint; povidone iodine five-minute paint; one-step iodophor with alcohol/water-insoluble film; one-step iodophor with alcohol/water-insoluble film and iodine antimicrobial incise drapes. The study involved 209 patients in four groups and was underpowered to detect important differences in surgical wound infection (only 18 patients in total developed an infection). One patient (1/49 - two per cent) receiving the one-step iodophor with alcohol/water-insoluble film developed an infection, compared with seven in each povidone iodine group (7/45 - 15.6 per cent - in the povidone iodine five-minute paint group; 7/49 - 14.3 per cent - in the povidone iodine paint group), and three (3/48 - six per cent) in the iodophor with alcohol/water-insoluble film and antimicrobial drapes group.

Iodine and alcohol were compared in two very small studies. Alexander et al (1985) compared a one-minute alcohol scrub with two different forms of iodine scrub and reported similar infection rates in each group: there was one infection in the 70 per cent alcohol group (1/76 - 1.3 per cent), one in the two per cent iodine in 90 per cent alcohol group (1/81 - 1.2 per cent) and also one in the 70 per cent alcohol with povidone iodine soap followed by two applications of povidone iodine group (1/77 - 1.3 per cent).

Lorenz et al (1988) compared an iodophor scrub plus an application of iodophor solution with 70 per cent isopropyl alcohol. Five patients developed an infection - two in the iodophor scrub group (2/41 - 4.9 per cent) and three in the alcohol group (3/38 -7.9 per cent). However, this comparison is confounded in that the group scrubbed with alcohol also received iodophor-impregnated drapes.

Only one study, involving 371 patients undergoing clean surgery, compared iodine with chlorhexidine (Berry et al, 1982). Of 176 in the povidone iodine group 28 (15.9 per cent) developed an infection, compared with 8/195 (4.1 per cent) in the chlorhexidine group.

Three studies compared single-step with multiple-step applications of solution (Segal and Anderson, 2002; Roberts et al, 1995; Alexander et al, 1985). Alexander et al (1985) gave groups a single application of preoperative antiseptic while one-third received povidone iodine soap followed by two applications of povidone iodine paint. The results in the multiple-application group were similar to those of the single-application groups.

Four studies compared the use of iodophor antimicrobial incise drapes with cloth drapes (Segal and Anderson, 2002; Lorenz et al, 1988; Dewan et al, 1987; Alexander et al, 1985). Dewan et al (1987) prepared all 365 patients with iodophor in alcohol then randomised them to one of two groups: one with iodophor antimicrobial incise drapes and one with cloth drapes. Nine out of 190 (4.7 per cent) patients in the antimicrobial incise drapes group developed an infection compared with 5/175 (2.9 per cent) of those with cloth drapes. This study was underpowered, therefore it was not possible to detect clinically important differences in infection rates. Lorenz et al (1988) compared iodophor antimicrobial incise drapes with cloth drapes but this study was confounded by differences in the way patients were antiseptically prepared.

Challenges to interpretation

There were challenges to determining a definitive evidence base for using preoperative antiseptics. For example, the preoperative skin antiseptics examined in the studies differed in ingredients, nomenclature and strength according to the manufacturer, date manufactured and country of origin, precluding any direct comparison.

Universal definitions and explicit statements regarding products and procedures are essential for facilitating robust collection and analysis of data.

The measurement of surgical site infection was disappointing, with some of the six studies having unclear definitions. All the studies that were reviewed involved too few patients to detect statistically significant clinically important differences in infection rates (Khan et al, 2003). This lack of homogeneity between antiseptics and study size prevented meta-analysis. A narrative review of the studies has therefore been provided instead.

Discussion

In most cases, participants were recruited from a very specific patient population (adults undergoing clean surgery in an operating room). For this reason, applying the results to other populations such as neonates, children or those undergoing contaminated surgery must be considered with caution. Another major limiting factor is the relatively small size of the studies which, in turn, has produced rather weak and ambivalent evidence.

One study demonstrated a higher rate of infection in the povidone iodine group than in the chlorhexidine group, and this was reported as being statistically significant for clean surgery (Berry et al, 1982). Based on the scant evidence available in the systematic review, iodophor antimicrobial incise drapes do not appear to reduce surgical wound infection rates.

All of the studies reviewed had undertaken some type of cost analysis of antiseptics, but no details of this were included in the review because of the diverse analytical techniques used. Patients with known sensitivity to the antiseptics used were excluded from all of the studies. In turn, none reported any patient allergies or toxicity to the antiseptics, suggesting that adverse events in preoperative antisepsis are rare. Issues associated with the application of antiseptics have been covered elsewhere (Edwards et al, 2004) and so will not be explored here, nevertheless they underpin decision-making in preoperative antisepsis.

Recommendations

No evidence based on the outcome of surgical wound infection was found that supported a cessation of preoperative antisepsis. Similarly, current guidance regarding the correct application of preoperative antiseptics should be adhered to unless further evidence emerges to support a change of practice (Mangram et al, 1999).

No definitive answer can be given to the question of which specific antiseptics should be used because the evidence is of variable quality. As with many explorations of current evidence, a plea for more research is made. This should involve a large, multicentre randomised controlled trial comparing the major preoperative antiseptics under varying conditions and using various types of surgery and areas of the body.

  • This article has been double-blind peer-reviewed.

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Learning objectives

Each week Nursing Times publishes a guided learning article with reflection points to help you with your CPD. After reading the article you should be able to:

  • Understand the importance of preoperative antiseptics in preventing infection;
  • Know the variety of approaches and methods available;
  • Become familiar with the current evidence on preoperative antiseptics;
  • Reflect on how this can be applied to practice.

Guided reflection

Use the following points to write a reflection for your PREP portfolio:

  • Outline your place of work and why you read this article;
  • Write about current practice in your area;
  • Identify how the recommendations in this article fit with your current practice;
  • List any new information you have found;
  • How will you apply what you have learnt to practice.
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