Forced-air patient warming systems do not disturb laminar airflow in the OR, according to an Anesthesia and Analgesia study. Research published in this month's British Journal of Bone and Joint Surgery, however, contradicts those findings.
In the Anesthesia and Analgesia article, Dutch researchers tested the impact of forced-air upper-body and underbody blankets on laminar flow - which dispenses highly filtered air over the sterile field to reduce airborne bacteria - by assessing particle counts above the surgical site during abdominal surgery. Particle concentration was reduced in both cases compared to measurements taken in other areas of the OR, and the blankets caused no statistically significant difference in particle counts, regardless of which setting (off, ambient or high) was used on the forced-air warming units.
The study, which was sponsored by 3M, manufacturer of the blankets used in the research, notes that neither the forced-air warming blanket or blower generated upward air that interfered with the normal uni-directional stream of the laminar airflow system, and "activation of forced-air warming does not reduce operating room air quality, even during laminar flow ventilation."
In the JBJS study, British researchers compared the infection rates of hip replacement patients who were warmed with forced-air systems or air-free conductive fabric. One of this study's authors disclosed a previous financial relationship with the manufacturer of the conductive fabric product.
The air-free systems cut implant infection rates by nearly 75%, according to the study's authors, who say forced-air units disrupted proper operating room ventilation and "resulted in the development of hot-air convection currents between the surgeon's body and the operating table, that transported (contaminated) floor-level air upwards and into the surgical site."
Air-free warming is therefore recommended over forced-air warming for orthopedic procedures, the authors conclude.
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