|Professor Paul Myles|
The World Health Organization (WHO)’s recommended guidelines on surgical wound infection, one of the most common serious post-operative complications, has been questioned by Monash University researcher and Alfred Health clinician Professor Paul Myles.
Patients with surgical site infections (SSI) are twice as likely to need admission to intensive care as other post-operative patients and are twice as likely to die. Surgical site infections are estimated to require an extra two million bed days a year and are believed to add a one billion-dollar cost to health care providers in Australia.
Professor Paul Myles, Director of the Department of Anaesthesia and Perioperative Medicine at The Alfred Hospital and Monash University, says the WHO recommended practice of administering supplemental oxygen to patients during and after surgery to prevent SSI was unfounded and expensive.
In an editorial published late last year in the influential 'British Journal of Anaesthesia' Professor Myles said that a review of available literature showed that the practice wasn’t supported by data.
“My department at the Alfred and I are very evidence-based. I followed that particular literature and my view is the guideline is not based on good evidence,” he said.
Professor Myles said that while there was early evidence supporting the role of supplemental oxygen in reducing the risk of SSI, published in 2000, there have been conflicting results from numerous randomised clinical trials since. The main authors of the early study, Professor Andrea Kurz and Dr Daniel Sessler of the Cleveland Clinic in Ohio, US, have since conducted larger and better studies that showed it doesn’t work, he said. Professor Kurz co-authored Professor Myles’ editorial in the journal.
He said the “definitive” PROXI trial – a multi-centre, randomised trial of 1400 patients undergoing surgery – found no evidence of any beneficial effect of supplemental oxygen; SSI occurred in 131 of 685 patients (19%) receiving 80% oxygen and in 141 of 701 (20%) receiving 30% oxygen. A long-term follow-up study found poorer survival in the supplemental oxygen group.
Despite the contradictory studies, the World Health Organization (WHO) Guidelines Development Group published a recommendation that adult patients undergoing general anaesthesia and tracheal intubation for surgical procedures should receive supplemental oxygen intraoperatively, and if feasible, for two to six hours afterwards to reduce the risk of SSI.
Professor Myles said that other experts around the world had similarly protested the recommendation. “I would hope the WHO is reconsidering it,” he said.
Supplemental oxygen is believed to work by getting into the tissues around a wound to help white blood cells kill bacteria – an idea Professor Myles said was questionable. “It doesn’t make sense because if you breathe in a higher concentration of oxygen, at the tissue level of where the wound is the amount of oxygen that can get into tissue is no different to that which you and I are breathing in room air. The science was suggestive but incomplete – we contest it on the grounds of the physiology of oxygen transport.”
The practice was expensive, particularly to hospitals in developing countries such as Papua New Guinea and Uganda, which may use it at the expense of other measures that were beneficial, he said.
Professor Myles said that there were many alternative ways of countering wound infection including the use of surgical masks, alcohol-based handwashes and antibiotics, although antibiotic resistance meant that antibiotics alone were not a solution.
“We should only be using things that work and are not harmful and which don’t add cost to the healthcare system,” he said.
Myles PS, Kurz A. Supplemental oxygen and surgical site infection: getting to the truth. Br J Anaesth. 2017 Jul 1;119(1):13-15. doi: 10.1093/bja/aex096.