Forced air waste, when heated, can rise and then fall directly into a patient’s open surgical wounds.
Air should never rise during surgery and floor air is nearly always contaminated. Anything below table height is also likely contaminated. Nearly 1000 watts of waste heat from a lower body or underbody forced air warming blanket escapes from under the surgical drapes at their lower edge near the floor, warming the floor air that has the highest concentration of airborne contaminants.
The risk of infection is especially serious for patients undergoing hip or knee replacement surgery, heart surgery to implant artificial valves or joint replacement surgery, especially hip replacements and knee replacements.
In these cases, very small amounts of contaminants can cause serious effects—a single bacterium can cause a PJI. This is because the body’s defences are weakened by the presence of the artificial joint. This foreign material is one reason the surgical site is so vulnerable to infection, and why maintaining a sterile surgical field is so important.