Forced-air warming and ultra-clean ventilation do not mix

An investigation of theatre ventilation, patient warming and joint replacement infection in orthopaedics

P. D. McGovern, M. Albrecht, K. G. Belani, C. Nachtsheim, P. F. Partington, I. Carluke, M. R. Reed

Abstract

We investigated the capacity of patient warming devices to disrupt the ultra-clean airflow system. We compared the effects of two patient warming technologies, forced-air and conductive fabric, on operating theatre ventilation during simulated hip replacement and lumbar spinal procedures using a mannequin as a patient. Infection data were reviewed to determine whether joint infection rates were associated with the type of patient warming device that was used.

Neutral-buoyancy detergent bubbles were released adjacent to the mannequin’s head and at floor level to assess the movement of non-sterile air into the clean airflow over the surgical site. During simulated hip replacement, bubble counts over the surgical site were greater for forced-air than for conductive fabric warming when the anaesthesia/surgery drape was laid down (p = 0.010) and at half-height (p < 0.001). For lumbar surgery, forced-air warming generated convection currents that mobilised floor air into the surgical site area. Conductive fabric warming had no such effect.

A significant increase in deep joint infection, as demonstrated by an elevated infection odds ratio (3.8, p = 0.024), was identified during a period when forced-air warming was used compared to a period when conductive fabric warming was used. Air-free warming is, therefore, recommended over forced-air warming for orthopaedic procedures.

Footnotes

  • The author or one or more of the authors have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article.

  • Supplementary material. A video demonstrating forced-air warming is available with the electronic version of this article on our website at www.jbjs.org.uk

  • Received March 15, 2011.
  • Accepted July 12, 2011.
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