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Discovery that patients with end-stage kidney disease on hemodialysis are at high risk for allergic reaction to a common antiseptic leads to change in hospital policy at St. Michael’s, UHN

Toronto, July 17, 2019

By Anna Wassermann

Dr. Peter Vadas
Dr. Peter Vadas

A new case series published in the Canadian Journal of Anesthesia is the first to identify a high-risk group for serious allergic reaction to chlorohexidine – an antiseptic commonly used during surgical procedures.

The research, co-led by Dr. Alex Ho, an anesthesiologist at St. Michael’s Hospital, and Dr. Peter Vadas, head of Allergy and Clinical Immunology and a scientist in the Li Ka Shing Knowledge Institute, found that patients with end-stage kidney disease on hemodialysis are at increased risk for developing chlorohexidine-induced anaphylaxis.

These results, informed by scientists and clinicians from St. Michael’s and the University Health Network (UHN), have prompted both organizations to ban the use of chlorhexidine-coated devices in kidney transplant surgery. We connected with Dr. Vadas to learn more about the team’s recent research and the resulting changes to hospital policy.

What did you set out to study?

The study began as a quality assurance project led by Dr. Ho, who was asked to investigate circumstances around severe events that may occur while patients are under anesthesia. While evaluating various cases, Dr. Ho noticed that a number of patients scheduled to undergo kidney transplant surgery had severe perioperative events. Upon further evaluation, he noticed that all of the events occurred after placement of chlorhexidine-coated central venous catheters and all occurred in patients who had been on hemodialysis. With this in mind, the patients were referred for allergy investigations.

How was it determined whether patients experienced an allergic reaction to chlorohexidine?

Ten patients underwent allergy skin tests to all drugs administered prior to the intraoperative event. These included anti-rejection drugs, antibiotics and anesthetic agents. These tests were all negative, but in five patients, both skin tests and blood tests were positive for chlorhexidine allergy.

What were your key findings?

For the first time, we identified patients with end-stage kidney disease on hemodialysis as being at increased risk for developing an allergy to chlorhexidine, which is routinely used in many hemodialysis units across North America to disinfect fistulas – the pathway created by surgeons in a patient’s body to allow for blood to flow in and out of a dialysis machine – before inserting a dialysis needle.

We also found that perioperative exposure to chlorhexidine-coated central venous catheters – those that go straight into veins – tends to trigger life-threatening anaphylactic reactions in patients who have become sensitized to chlorhexidine during hemodialysis.

In reviewing other potential cases of allergic reactions during surgery, we’ve not been able to identify any other clusters of cases related to the use of chlorhexidine-coated catheters. This finding, at least so far, is unique to hemodialysis patients undergoing kidney transplant surgery.

How have these results informed hospital policy?

Having shown that hemodialysis patients are at markedly increased risk of potentially life-threatening chlorhexidine-induced anaphylaxis, it’s now become standard policy at St. Michael’s and UHN to ban the use of chlorhexidine-coated devices in kidney transplant surgery. St. Michael’s serves as a kidney transplant centre for more than 20 regional hospitals, and given the sheer number of patients, pre-screening all potential transplant recipients for an allergy to chlorohexidine isn’t practical. Since we don’t have control over chlorhexidine exposures in hemodialysis units at outside centres, a ban on chlorhexidine-coated devices in this setting is the most practical approach.

We’ve also learned that chlorhexidine-induced allergic reactions are not unique to patients at St. Michael’s, having identified an additional case at UHN. This implies that this high-risk group has gone unnoticed so far, perhaps because of severe events during surgery that weren’t recognized as anaphylaxis, or because St. Michael’s is the first centre to undertake this type of quality assurance study. We note, however, that our approach of banning the use of chlorohexidine-coated devices in this high-risk group could have impact throughout North America and Europe.

Are there any next steps for this research?

We’re systematically reviewing all kidney transplant cases retroactively to look for evidence of milder intraoperative reactions. This may lead to an investigation to assess the prevalence of mild reactions that have gone unrecognized.

Research and quality assurance in our Kidney Transplant Program is one area of our expertise in kidney transplant. Our program is celebrating its 50th anniversary this year and we want to encourage more people in our communities to register as organ donors in celebration of this milestone.

  • Support our campaign, #MyTXAnniversary, by signing up to be a donor, or checking your registration status online today at our donor drive.


This paper is an example of how St. Michael's Hospital is making Ontario Healthier, Wealthier, Smarter.

About St. Michael's Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in more than 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the Hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael’s Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.

About Unity Health Toronto

Unity Health Toronto, comprised of Providence Healthcare, St. Joseph’s Health Centre and St. Michael’s Hospital, works to advance the health of everyone in our urban communities and beyond. Our health network serves patients, residents and clients across the full spectrum of care, spanning primary care, secondary community care, tertiary and quaternary care services to post-acute through rehabilitation, palliative care and long-term care, while investing in world-class research and education. For more information, visit www.unityhealth.to.


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