Convection warmers — not just hot air

Abstract

SummaryWe sought to determine whether the forced air convection warmers (nine Bair Huggers, Augustine Medical, and one Warm Touch, Mallinkrodt Medical) used in our operating theatres could be a source of microbial pathogens. Agar plates were placed directly in the air stream of the warmers. Four of these grew potentially pathogenic organisms. When the warmers were set to blow through perforated blankets, no growth occurred. Three of the warmers were swabbed and sites of colonisation were found in their hoses. After fixing a microbial filter to the end of the hose, organisms were no longer detectable. We conclude that these warming devices are a potential source of nosocomial infection. They should only be used in conjunction with perforated blankets, should have their microbial filters changed regularly and their hoses sterilised. The inclusion of a microbial filter into the nozzle of the hose could be incorporated into the design of the warmer.

Peri‐operative warming devices: performance and clinical application

“…However, the correct use of microbial filters and the recommended perforated blankets has been shown to prevent their transmission [77]. Moreover, analysis of theatre air samples in positive pressure theatres has shown a significant decrease in bacterial counts when forced-air warming was used correctly [80].…”

“…Evidence suggests that forced-air warmers may also harbour microbial pathogens that have the potential to be emitted into the operating theatre environment via the air warmer hose [77][78][79]. However, the correct use of microbial filters and the recommended perforated blankets has been shown to prevent their transmission [77].…”

A randomised controlled trial of the electric heating pad vs forced‐air warming for preventing hypothermia during laparotomy

“…Unlike forced-air warming, there is no consumable associated with use of the heating pad, so the latter is cheaper in long-term use. For forced-air warming, the hose, the warming units and even the brand new commercial blankets have been shown to be potential sources of nosocomial infection [3][4][5]. The heating pad warming system, which comprises a control unit, an electric cable and a heating pad, has no hidden space for bacterial colonisation and is theoretically easier to clean.…”

Diagnosis, prevention and treatment of accidental and perioperative hypothermia

“…Further concerns exist about bacterial contamination of the forced-air system [110] . A possible transfer of microbial pathogens with the airstream into the surgical field has been described [2] ; however, several studies have challenged the clinical relevance of these findings and found no difference in bacterial dispersion with or without forced-air warming [5,46,120] .…”