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.