Non-pharmaceutical methods to reduce SSI
August 2008
The European symposium at the Society for Surgical Infection Congress, held in Turkey, examined some of the non-pharmaceutical strategies used in the fight against SSIs – ranging from microbial sealants, to autologous blood transfusions. CHRIS BIRD reports.
“Surgical site infection (SSI) is today the most important problem facing surgeons,” said Professor Miguel Cainzos as he began his keynote presentation. “Postoperative infections not only destroy the surgeon’s technical work but they also increase postoperative morbidity and mortality while reducing the quality of surgery and hampering the daily running of surgical departments.”
Prof. Cainzos presented several studies suggesting that wound infections after “clean” surgery are more common than previously thought. A 1999 study of hernia repair patients1 showed a 6.9% infection rate and a 2008 study in breast surgery patients showed an overall infection level of 5.3%, rising to 12.4% for patients who had immediate implant reconstruction after mastectomy.2
Professor Samuel Wilson pointed out that: “Even if only 2% of patients suffer an infection that adds up to 12,000 patients a year with an average additional cost of $30,000.” Vascular grafts and mechanical heart valves typically have a 4% surgical infection rate and the average additional costs are $40,000 and $50,000 respectively.3
The economic cost to hospitals is important but more important is the human cost. SSI’s lead to an average two weeks extra time in hospital, a five-fold increase in readmission rates and a doubling in mortality.
“Is the incidence of postoperative infection within our control?” asked Prof. Wilson. “Yes” was his answer. “We know the value of non-pharmaceutical ways of preventing SSI’s and even small changes can make a significant difference.”
Methods to reduce SSIs
Maintaining body temperature during surgery can have a dramatic impact on postoperative infection. One study found an infection rate of 5.5% for patients where normothermia was maintained compared to 16.7% in patients who became hypothermic.4 Glucose control in diabetic patients also reduces surgical site infections. A study of 2,467 patients undergoing cardiac surgery showed an infection rate of just 0.8% when insulin was used continuously to maintain blood glucose at below 200 mg/dL. This compared to an infection rate of 2% for the control group who received intermittent subcutaneous insulin.5 Supplemental oxygen also reduces postoperative infection with one study showing a 5% infection rate when patients received 80% inspired oxygen compared to 11% infections when 30% oxygen was used.6 Prophylactic antibiotics discontinued within 24 hours of surgery,7 skin disinfection with solutions such as Povidone, avoiding hair removal with razors8 and, if possible, using autologous blood transfusions, all contribute to reducing the risk of infection as, of course, does good theatre hygiene.
Microbial sealants
Two new studies, presented at the symposium, suggested that microbial sealants also have a role. “We know that skin flora are the major source of wound contamination in clean surgery so if we can stop this it should be an advantage,” said Prof. Wilson. Microbial sealants fix bacteria to the skin and prevent their migration into the wound. This should reduce the contamination of wounds and hence infection.
Integuseal, from Kimberly-Clark, is a film-forming cyanoacrylate liquid that dries within a few minutes of application to the skin. It forms a microbial barrier designed to prevent intraoperative contamination from skin flora which colonise hair follicles and other sites which are not sterilised by swabbing with povidone-iodine or chlorhexidine. A US trial in 177 patients undergoing hernia repair compared patients prepared with standard 10% povidone-iodine to the standard preparation plus Integuseal.9 “The results”, said Wilson, “show a 15.7% decrease in wound contamination for patients treated with the microbial sealant.”
Dr Pascal Dohmen, a cardio-vascular surgeon at the University Hospital Charité in Berlin, one of the largest hospitals in Europe, presented data showing that reducing wound contamination does translate into reduced infection rates. In nearly 400 case-matched patients undergoing coronary artery bypass graft he achieved a SSI rate of 1.1% compared to 4.8% for cases not using a microbial sealant.10 The results have been enough to convince the Charité Hospital to introduce Integuseal for all cardiac surgery patients.
“Surgical infection is not what it used to be,” said Per-Olof Nyström, professor of surgery and a consultant surgeon at the Karolinska Institutet, Sweden. “Today, it is rare to see frank pus from a wound. At the Karolinska, we say there is a surgical infection if the patient receives antibiotics – even though many have a wound healing problem rather than an infection.”
Data collected at the Karolinska Institutet suggests that postoperative complications in colorectal surgery patients are around 30%, with no improvement in the last fifteen years, and audits from the US suggest that surgical infection rates have not fallen since the widespread introduction of prophylactic antibiotics in the 1970’s.
“We just do not know enough about why complications happen to be able to reduce them,” said Professor Nyström.
Using data from 4,588 colorectal surgery patients, Prof. Nyström explained the problem. A total of 1,235 patients had complications with 57 deaths and 271 re-operations. Only 2 deaths and 31 re-operations could be directly attributed to fever or surgical site infection, but because other complications have an intermediate or high likelihood of being treated with antibiotics they also meet the criteria for SSI. Forty per cent of all deaths and 56% of all re-operations can be attributed to SSI because of a lack of clarity in defining surgical infection. “Just being able to culture bacteria from a wound does not mean it is an infection,” said Prof. Nyström. “We need to look at the physiology of the patient and we need new ways to classify postoperative complications and to distinguish between wound healing problems and infection.”
Surgical site infection is a complex problem and will not have a simple solution. There is a need for further research, a clearer understanding of the exact definition of an infection and unequivocal data on the clinical efficacy of new measures to reduce SSI. However, new ways of reducing infections are having an incremental effect. As Prof. Wilson commented: “The small cost of each of the steps in preventing wound infection such as prophylactic antibiotics, skin disinfection and microbial sealant, must be weighed against the much greater cost of a wound infection. It is worth it.”
References
1 Cainzos M., Lozano F., Pulsay I., Hau T. et al. Postoperative wound infection after hernia repair: a European study. Hernia 1999: 3 (Suppl 2): S67-S68.
2 Olson M.A., Chu-Ongsakul S., Brandt K.E. et al. Hospital associated costs due to surgical site infection after breast surgery. Arch Surg 2008: 143: 53-60.
3 Darouiche R.O. Clinical and economic consequences of surgical implant infection. N Engl J Med 2004; 350: 1422-1429.
4 Kurz A., Sessler D.I., Lenhardt R. Perioperative normothermia to reduce the incidence of surgical wound infection and shorten hospitalization. Study of wound infection and temperature group. N Engl J Med 1999; 334: 1209 – 1215.
5 Furnary A.P., Zerr K.J., Grunkemeier G.L., Starr A. Continuous intravenous infusion with insulin reduces the incidence of deep sternal wound infection in diabetic patients after cardiac surgical procedures. Ann Thorac Surg 1999;67: 352-360.
6 Grief R., Akca O., Horn E.P. et al. Supplemental peri-operative oxygenation to reduce the incidence of surgical wound infection. N Engl J Med 2000; 342: 161.
7 Taylor E.W., Byrne D.J., Leaper D.J. et al. Antibiotic prophylaxis and open hernia repair. World J Surg 1997; 21:811-815.
8 De Geest S., Kesteloot K. et al. Clinical and cost comparison of three postoperative skin preparation protocols in CABG patients. Prog Cardiovasc Nurs 1996; 11: 4-16.
9 Towfigh S., Cheadle W.G., Lowry S.F., Wilson S.E., Malangoni M.A. 47 Interscience Conference on Antimicrobial Agents and Chemotherapy, September 18, 2007.
10 Dohmen P. et al. J Hosp Infect 2008 (in press).
• The meeting was sponsored by an educational grant from Kimberly-Clark.
NICE consultation on SSI
Consultation on the draft NICE guideline ended in June with publication of the final guideline anticipated for October 2008. NICE recognise the importance of SSI and estimate that “at least 5% of patients undergoing a surgical procedure develop an SSI” which may range from being trivial to life threatening.
The draft guideline suggests: “Most SSI’s are potentially preventable as their occurrence usually depends on contamination of an incision during surgery with the patients own endogenous organisms. “SSI’s cause a considerable financial burden to healthcare system, which does not include the considerable indirect costs arising from loss of productivity and quality of life issues.”
Key priorities for implementation include only removing hair if necessary and with electric clippers, antibiotic prophylaxis, skin preparation with antiseptics and perioperative warming. In cases where an incise drape is used it should be iodophore impregnated unless the patient has an iodine allergy. NICE recommend further research to establish the value of supplemental oxygenation and tight postoperative blood glucose control as well as closure methods and wound dressings.
Miguel Cainzos is professor of surgery and a general surgeon in Santiago de Compostela and a former President of the Surgical Infection Society of Europe (SIS-E). Since 2005 he has been director of the SSI-E’s Internet Course on Surgical Infections which over 1,000 clinicians in 36 countries have now completed.
Dr Pascal Dohmen is a cardiac surgeon in the Department of Cardiovascular Surgery at the Charité University Hospital in Berlin.
Per-Olof Nyström is professor of surgery at the prestigious Karolinska Institute in Stockholm, Sweden, and a consultant surgeon specialising in colorectal surgery.
Samuel E. Wilson MD is professor of surgery at the University of California, Irvine.
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