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%.
Torso-style disposable blankets
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.
A study conducted by other orthopedic surgeons and published in November 2011 in the Journal of Bone & Joint Surgery positively linked Bair Hugger warming to increased joint replacement infections. The surgeons showed that their deep joint infection rate dropped 74% when Bair Hugger warming was discontinued.
“While Bair Hugger has served most surgical patients well for the past 25 years,” said Dr. Augustine, “these two studies along with three others recently published clearly show that hot-air warming has unintended consequences and should never be used during total joint replacement surgery. Contamination of the sterile surgical field is a serious risk to patient safety.”
The BJJ article follows several other recently published, peer-reviewed studies in the Journal of Bone & Joint Surgery (Br), the American Journal of Infection Control, Anaesthesia, Orthopedic Review and Anaesthesia & Analgesia relating to the potential contamination of surgical sites by forced-air warming devices.
Citations to other studies mentioned in this article: