Journal of Hospital Infection: Forced-Air Warming An Infection-Control "Hazard" in Implant Surgery

StopSurgicalInfections.org recently submitted a press release regarding a review article published by Journal of Hospital Infection.  The press release is as follows:

Surgical-infection experts have unambiguously concluded that forced-air warming “...does contaminate ultra-clean air ventilation….” in the operating room. Their advice: Use air-free warming during implant surgery.

PRLog - Nov. 12, 2014 - MINNEAPOLIS -- “Infection Control Hazards Associated with the Use of Forced-air Warming in Operating Theatres," appears in the scientific publication of the Healthcare Infection Society, Journal of Hospital Infection. The article, in press, can be found on-line at www.journalofhospitalinfection.com/article/S0195-6701%2814%2900245-X/abstract?showall=true=

The authors, including surgeon D.L. Leaper, chair of the committee that drafted the UK’s surgical-site infection guidelines, summarized the findings of 10 peer-reviewed, published studies regarding the infection risks of forced-air warming.  Their conclusions:

• No studies have shown that forced-air warming (“FAW”) reduces surgical infections—other than in colorectal surgery.
• In implant surgery, even minor contamination of the operative field can be catastrophic.
• FAW devices contaminate the operative field.

Patient Advocate Warns Against Forced-Air Warming

A well-known patient advocate now urges surgical patients to avoid forced-air warming—even to change hospitals if necessary.

The advocate, Rosie Bartel, speaks from experience. Infected with MRSA during a knee-replacement procedure at a hospital using forced-air warming, Bartel has undergone 27 subsequent operations— including amputation of her leg to the hip. The MRSA remains active.

After researching how the pathogens rose from the floor of the operating room into the sterile field, Bartel concluded that Bair Hugger warming blew particles into her wound, causing the MRSA infection. 

Bartel has a website (www.RosiesDream.com) to share her findings and give her advice to patients. Click on the video below. She has some powerful things to say.

A former educator, Bartel works closely with Partnership for Patients and the Institute for Healthcare Improvement. She will be co-chair of IHI’s national conference this year.

Infection Risk from Forced-air Warming Considered; Study on Bacterial Contamination Recommended

International Orthopedic Consensus 

“We recognize the theoretical risk posed by forced air warming blankets,” concluded the Consensus Statement recently released by the International Consensus on Periprosthetic Joint Infection.  While not urging a change in practice, the Consensus Statement recommended that further studies be undertaken regarding the safety of forced-air warming (“FAW”) in orthopedic implant surgery.
Delegates from more than 50 countries and 80 different societies met in August 2013 to evaluate scientific literature and identify areas for further research.  Among the other conclusions relating to periprosthetic joint infections and the risk of airborne contamination:
 
1. Airborne particulate bacteria are a major source of contamination in the operating room.  The number of airborne bacteria around the wound is correlated to the incidence of periprosthetic joint infections.  Bacteria “circulate through the operating room via air currents.”

“Legg et al,” the Consensus Statement noted, “found increased particles above the surgical site when using FAW compared to radiant warming.” To be precise, the Legg study, published in Bone & Joint Journal, found 2,000 times more contaminant particles in the air over the wound with Bair Hugger forced-air warming than with air-free HotDog conductive warming.  With HotDog patient warming, only 1,000 particles per cubic meter of air were present. With Bair Hugger warming, the particle count was 2,174,000 per cubic meter, an increase of 217,300%.

Nursing Journal: Forced-Air Warmers May Allow Pathogens to Contact Surgical Wounds

October 10, 2013

   

AORN Journal, noting concerns about infection risk from forced-air warmers, called for multi-center, randomized, controlled trials. Evidence of bacteria in the air-flow paths of forced-air warmers; authors ask manufacturers to consider redesign.

In a continuing-education review article in the October issue of AORN Journal, published by the Association of Operating Room Nurses, the authors examined 192 sources.  Their conclusions included the following:

• “Clinicians should take steps to prevent health care–associated infections from the use of forced-air warmers….”  Such steps include “routinely and meticulously” cleaning the devices.

•  Forced-air warmers may interrupt the flow of filtered air toward the area of the wound and may allow dust particles containing pathogenic organisms to come into contact with the wound.

•  Five separate studies suggested that forced-air warmers could be harboring bacteria or bacteria-containing particles.

Among the research considered by the authors was “Forced-air warming and ultra-clean ventilation do not mix: an investigation of theatre ventilation, patient warming and joint replacement infection in orthopaedics,” by UK orthopedic surgeon PD McGovern et al and published in the Journal of Bone & Joint Surgery.  The research included 1,437 patients undergoing hip or knee replacement.  The “Finding and comments” of the AORN Journal authors included:

“High risk of developing deep infections for subjects warmed with forced-air warming systems (odds ratio, 3.8; P=.024).”

Recent A & A study: “These findings warrant future research into the effects of forced air warming…during contamination-sensitive surgery.”

August 2013
 
Research in the August edition of Anesthesia & Analgesia, a publication of the International Anesthesia Research Society, and appearing under the name of the Anesthesia Patient Safety Foundation stated:

 “[F]orced air warming was found to establish convection currents that mobilized resident air from nonsterile areas (under the anesthesia drape) upward and into the surgical site.”

The clinical concern, according to the article, is that the convection currents created by Bair Hugger will mobilize contaminants and/or impede the ventilation systems’ ability to clear contaminants from the surgical site.  The concerns, they stated, “are most relevant for smaller airborne particles…such as free-floating bacteria and skin cell fragments.”

The study compared the impact of Bair Hugger warming with air-free HotDog conductive fabric warming.  No convective currents were detected when HotDog warming was applied.  In explanation, the scientists stated:

 “Because conductive blankets (like HotDog) are localized in their application, they tend to have higher thermal efficiencies and contribute less excess heat to the environment than forced air.”

In contrast, Bair Hugger “was found to have a significant disruptive impact on clean airflow patterns over the surgical site….”

AANA Journal: 96% of Bair Hugger Blowers Contaminated

August 2013

Research published in the August issue of AANA Journal revealed that 96% of Bair Hugger forced-air warming (FAW) blowers studied were generating “significant levels of contamination.”  The researchers, including two UK orthopedic surgeons, measured up to 110,000 particles per cubic foot--82,500 particles per second.  More than 70% of the blowers “had hose-end airflows with higher contamination levels than in intake airflows.”

The contaminates, therefore, were incubated inside the Bair Hugger blowers.

The problem, researchers concluded, arises from the blowers’ inadequate air filtration. Originally designed to provide 93.8% efficient intake filtration, the current-model Bair Hugger filters perform at only 63.8% efficiency.  This poor filtration, the authors stated, suggests “that inadequate FAW device intake filtration...led to a significant buildup of internal microbial contamination in the FAW blowers sampled.”

"Wave" of Bair Hugger Litigation?

A news article published in Clinical Quality & Infection Control, a publication of Becker’s ASC Review, stated:

“Recent studies published in medical journals questioning the safety of forced-air patient warming in orthopedic implant and other ultra-clean surgeries could mean a wave of new litigation.”

The studies, said the writer, show that forced-air blowers contain internally generated airborne contaminates and microorganisms that “could contaminate the surgical site….”

Infection Guidance: Air Turbulence in Operating Room Increases Risk of Orthopedic Infection

In its Guide to the Elimination of Orthopedic Surgical Site Infections, the Association of Professionals in Infection Control and Epidemiology (APIC) states, “If airflow is interrupted, rapid air turbulence can stir settled particles, enabling them to become airborne thus increasing the risk for wound contamination.” By applying recent research to APIC’s Guidance, StopSurgicalInfections.org found that forced-air warming systems violate APIC’s Guidance “by drawing potentially contaminated particles from below the operating table into the surgical site.”   

Minneapolis, MN July 25, 2013

According to the Association of Professionals in Infection Control (APIC), the maintenance of uninterrupted, downward airflow during orthopedic surgery is “vitally important.” Several recent articles published in top peer-reviewed medical journals, however, confirm that forced-air patient warming, such as 3M’s Bair Hugger, produces rising, turbulent convection currents that can mobilize floor-level contaminants.

The printing and distribution of APIC’s Guide was sponsored by 3M.  APIC, of course, neither endorses nor is affiliated with this press release.

“The APIC guidance,” says Dr. Scott Augustine, inventor of Bair Hugger, “ summarizes the reason that researchers have questioned the safety of forced-air patient warming (“FAW”) in orthopedic implant and other ultra-clean surgeries.  I believe the research is conclusive—the largest study involved a retrospective analysis of 1,437 hip or knee replacements. It showed a 74.6% decrease in deep joint infection when FAW was discontinued and replaced with air-free warming.”

New ECRI Guidance Expresses “Concern” About Forced-Air Warming in Implant Surgery

In the latest issue of Health Devices, ECRI Institute analyzed the safety of forced-air patient warming, concluding that thermal currents are “particularly worrisome” in implant surgery. Dr. Scott Augustine, inventor of both Bair Hugger and (air-free) HotDog patient warming and CEO of Augustine Temperature Management, comments.

Minneapolis, MN (PRWeb), April 17, 2013 -  After reviewing multiple published, peer-review articles addressing the consequences of the convection currents created by the waste heat produced by forced-air devices, ECRI stated:

• “The disruption of air-flow patterns is particularly worrisome in laminar-flow and ultraclean ORs, in which a wide variety of implant surgeries are performed.”
• “This is especially concerning during orthopedic surgeries because contamination of the surgical site may present a greater risk of developing a PJI, which is harder to treat and resolve than would be the case with SSIs in general.”

Video Evidence of the Vortex Caused by the Radiant Waste Heat from FAW Blankets

The video clip below is an excerpt from a nurse education course.  It shows the vortex-effect caused by the radiant waste heat from forced-air patient warming (FAW) blankets, similar to what was recently studied and published by orthopedic surgeons A.J. Legg and A.J.Hamer.

The Legg and Hamer study, published in the Bone & Joint Journal in March 2013, is different than the four previous studies examining the unintended consequence of FAW.  Studies by Belani, Dasari, McGovern and a previous study by Legg all showed the mass effect of waste heat forming thermals under the drapes and rising from the floor to the surgical field.  The latest study is unique because it shows that the radiant heat travels through the drapes, interacts with the downward flow of air from the ceiling ventilation, and forms vortices that suck contaminated air from the floor.  Legg and Hamer discovered 2,000x more contaminant particles at the surgical site when FAW was used than when air-free HotDog patient warming was used.

This is especially concerning in orthopedic surgery, where airborne contaminants can cause devastating deep-joint infections.

As you’re watching the short video clip, notice the tight-spinning vortex captured by orthopedic surgeons in Northumbria, UK, towards the end.

Study: Contamination Increased 2000x With Bair Hugger Warming

Minneapolis, MN: March 14, 2013— The use of Bair Hugger forced-air warmers during surgery creates convection currents that capture particles below the surgical table, lifting them into the sterile surgical field, according to research recently published by orthopedic surgeons. The waste heat radiating through the surgical drape induced the formation of tornado-like vortexes of rapidly spinning air near the surgical site. The vortexes sucked contaminated air from the operating room floor and deposited it over the surgical wound. 

2,000 times more contaminant particles were found in the air over the wound with Bair Hugger warming than with air-free HotDog conductive warming. With HotDog patient warming, only 1,000 particles per cubic meter of air were present. With Bair Hugger warming, the particle count was 2,174,000 per cubic meter, an increase of 217,300% 

Concerned by convection currents produced by hot-air warming devices, orthopedic surgeons A.J. Legg and A.J. Hamer from Northern General Hospital in Sheffield, United Kingdom, compared the torso-style disposable blankets of 3M’s Bair Hugger system with the reusable, air-free HotDog conductive warming system. The surgeons released particles below the surgical table and then measured how many were transported to the surgical site. Neither surgeon has any financial relationship with either of the products studied. 

The study was published in the February issue of The Bone and Joint Journal and entitled “Forced-air patient warming blankets disrupt unidirectional airflow.” 

Dr. Scott Augustine, inventor of both products studied, stated, “Such a massive increase in airborne contamination is obviously a safety issue in contamination-sensitive surgeries. In joint replacement surgery, for example, a single airborne bacterium can cause a deep joint infection.” 

Periprosethetic joint infections are often catastrophic: immense pain and suffering, permanent disability and an enormous cost to the hospital. 

“Every joint infection is a disaster—both for the patient and the system,” said Dr. Augustine. “The process is horrific: ex-plant the joint, prolonged hospitalization, 6-8 weeks of IV antibiotics and then—assuming no amputation—re-implant the joint. The average cost is around $100,000.” More than 12,000 of these infections occur each year in the US, a rate that some see as a significant public health problem.

The Paradox of Forced-Air Patient Warming

Studies show that forced-air warming (FAW) reduces soft-tissue surgical infections. How can FAW be linked to increased deep-joint infections?

The paradox is easy to explain: BIOFILM.  A bacterium that lands on a prosthetic implant can secrete a coating of biofilm that protects it from both antibodies and antibiotics. Bacteria in soft-tissue cannot form effective biofilm coatings.

Secretion of biofilm allows a single airborne germ to cause a deep infection of a joint implant (Lidwell, 1983).  When the germ lands on the new implant, it protects itself in a biofilm coating and then sprouts weeks-to-months later as a catastrophic deep joint infection.  The increased airborne contamination from FAW vastly increases the chances of an airborne bacterium landing on the new implant.

In contrast, without biofilm protection, the germs in soft-tissue are susceptible to antibiotics and to an immune system activated by heat.  As a result, the creation of soft-tissue surgical infections require large inoculums of more than 100,000 germs (Elek & Cohen, 1957).

This also explains why soft-tissue surgical infections may not be increased by contaminated FAW air, while blowing even one germ into the surgical site during implant surgery can have significant negative concequences.

Watch this terrific video about bacterial biofilms 

produced by the Arthroplasty Patient Foundation:

Here is another interesting video about bacterial biofilms 

and orthopedic implants produced by the Arthroplasty Patient Foundation:

Evidence of the risks of forced-air warming just keeps growing.

A study published online ahead of print in Anesthesia & Analgesia concludes that forced-air patient warming produces waste heat that disrupts operating room ventilation airflows over the surgical site, transporting non-sterile air to the area and hindering the ventilation system’s ability to clear potential airborne contaminants.

“There are some in our industry that would like you to believe that hot air doesn’t rise,” says Dr. Scott Augustine, “this study proves, once again, that that argument is insulting to science and common sense.”

Belani, et al, focused on contamination-sensitive surgery at the University of Minnesota, using a mannequin draped for total knee replacement.  Introducing neutral buoyancy bubbles near the mannequin’s head, researchers found a significant increase in bubble-count over the surgical site when forced air warming was used, as opposed to conductive fabric or the control.  The study states:

3M accuses Augustine of "instilling fear through misleading claims." Really? Let's look at the facts...

Four independent peer reviewed studies have been published showing that forced-air patient warming devices generate convection currents that disrupt the sterile field.  One such study (McGovern, JBJS-br, 2011) even showed a 74% decrease in deep-joint infection rates after discontinuing the use of forced-air patient warming. They switched to air-free HotDog patient warming (1250 patients, 2.5 years).

Despite this strong evidence, 3M, the manufacturer of Bair Hugger® forced-air warming, has continued to obfuscate and assure the world that its forced-air warming products are universally safe.  In a recent letter to healthcare professionals, Bob Buehler, VP of 3M Patient Warming, even accuses us of “promoting a campaign designed to instill fear through misleading claims.”

To be clear: we are educating the healthcare community about a practice that puts orthopedic patients at risk for infection.  Every claim we make is backed by science and published research.  Our mission is to protect patients and to provide a safe, effective, and affordable solution. 

Evidence Growing Against Safety of Forced-air Patient Warming

Yet another peer-reviewed study—the third in the past five months—has been published showing that forced-air patient warming generates convection current activity in the vicinity of the surgical site, which could lead to contamination of the sterile field.

The study, published by Dr. Kiran Dasari in the March issue of Anaesthesia, is more evidence that a significant patient safety issue exists.  Surgeries with implanted foreign materials, like hip and knee replacements, could be greatly compromised depending on the type of warming technology used.

Another Study Shows the Risks of Using Forced-air Patient Warming

Researchers in the UK published a study in the February, 2012, issue of the Journal of Bone and Joint Surgery-Br examining the effects of forced-air warming on operating room airflow and surgical site sterility.

Summary:

“Forced-air warming resulted in a significant mean increase in the temperature (1.1°C vs 0.4°C, p<0.0001) and number of particles (1038.2 vs 224.8, p=0.0087) over the surgical site when compared with [HotDog®] warming, which raises concern as bacteria are known to require particles for transport.”
 

Study Links Forced-air Warming to Infections: 3.8x Increase In Orthopedic Implant Cases

Previously, research studying the effects of forced-air warming on laminar flow operating theaters was limited to contamination…until now.

The use of forced-air warming during orthopedic implant surgery was associated with a 3.8 times increase in deep joint infections as compared to warming patients without forced-air, according to a newly published study.

FAW's Impact on SSIs

“How can forced-air warming be unsafe when research shows that it reduces infections?”

This is a common question, and the best explanation was given by Yale scientist Dr. Marc Abreu in the October 2010 Anesthesiology News Review. In the article, titled New Concepts in Perioperative Temperature Management: Monitoring and Management, Dr. Abreu wrote that, “…any potential airborne contamination caused by FAW waste heat must have a negligible effect on soft tissue SSIs. However, patients undergoing surgery involving implanted foreign materials, especially for orthopedics, may be at higher risk for infection from airborne contamination.” (emphasis added)

The risk of infection with FAW, at least as established so far, is specific to ultra-clean surgeries involving implanted foreign materials: orthopedics, neuro, and cardiac. There is a fundamental difference in causation between soft-tissue infections and surgical infections involving implanted foreign materials—and that is the point commonly missed.

Latest Evidence of Forced-Air Contamination -- Must See

Here is the latest evidence of forced-air warming units contaminating the operating room by overcoming protective laminar flow ventilation. The room temperature tracer particles and bubbles are neutrally buoyant, which is to say they follow the air currents of the room. When forced-air warming units dump 900 watts of waste heat into the operating room, it is no surprise that we can visualize the effects: heat rises. Notice the laminar flow working properly with conductive fabric warming, or with forced-air "Heat OFF" as control. Then with "Heat ON" watch the stunning evidence of forced-air waste heat mobilizing air from the dirty floor and sending it right up into the surgical site, contaminating it. The evidence speaks for itself: as hot air rises, so does risk.

The Northumbria orthopedic team has set up their own blog to show their findings. With patient safety in mind, they have compiled excellent research and the visual evidence is stunning. To access their blog, click on the following link: www.northumbriaorthopaedics.blogspot.com

Laminar vs. Conventional Ventilation

Common Question: “My OR doesn’t use laminar flow. Does waste hot air still matter?”

Answer: Absolutely. Consider the following:

What is laminar ventilation and what is conventional ventilation?

Operating room air is typically introduced from the ceiling, moves towards the floor, and exits through the side vents. US standards for hospital construction require that operating room ventilation be filtered, at a minimum, to an efficiency of >90% for the removal of germ sized particles. Many ventilation systems do much better than that, by employing High Efficiency Particulate Air filtration commonly known as HEPA, which by definition removes >99.97% of germ sized particles from the airflow.