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In Response

Weissman, Charles MD; Murray, W. Bosseau MD

doi: 10.1213/ANE.0000000000000103
Letters to the Editor: Letter to the Editor

Department of Anesthesiology, Hadassah-University Hospital, Kiryat Hadassah, Jerusalem

Department of Anesthesiology, Pennsylvania State University College of Medicine, Hummelstown, Pennsylvania,

The subject of intraoperative hypothermia and its prevention is a complex issue. As pointed out in our editorial,1 on the one hand, there are studies demonstrating a reduced incidence of surgical wound infections when normothermia is maintained, while on the other hand, articles by Belani et al.2,3 demonstrate that the most common form of hypothermia prevention, forced-air warming, increases the number of particles above the surgical field. How this increase in particle numbers translates into infective potential is unclear because the bacterial burden of these particles has not been measured. It is the bacterial content of these particles that will determine their infective potential.

As Augustine4 points out, the infective potential of a bacterial inoculum is dependent on the material inoculated. Living tissue requires a larger inoculum than prosthetic material to become infected. A joint prosthesis, such as a hip or knee replacement, is especially vulnerable to a small inoculum and thus the precautions taken to prevent contamination.5 However, even suture material, polyfilament more than monofilament, can be a nidus for infection6,7 as can mesh used for a hernia repair.8 In fact, under experimental conditions, bacterial adherence was seen with an inoculum of <10 bacteria.8 Therefore, future studies of the aerosols caused by forced-air warmers should include examination of the potential inoculum carried by these aerosols as well as whether they can actually cause infections. Without such information, it is impossible to evaluate the advantages or disadvantages of forced-air warming from the viewpoint of infective potential.

Charles Weissman, MD

Department of Anesthesiology

Hadassah-University Hospital

Kiryat Hadassah, Jerusalem

W. Bosseau Murray, MD

Department of Anesthesiology

Pennsylvania State University College of Medicine

Hummelstown, Pennsylvania

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1. Weissman C, Murray WB. It’s not just another room. Anesth Analg. 2013;117:287–9
2. Belani KG, Albrecht M, McGovern PD, Reed M, Nachtsheim C. Patient warming excess heat: the effects on orthopedic operating room ventilation performance. Anesth Analg. 2013;117:406–11
3. Moretti B, Larocca AM, Napoli C, Martinelli D, Paolillo L, Cassano M, Notarnicola A, Moretti L, Pesce V. Active warming systems to maintain perioperative normothermia in hip replacement surgery: a therapeutic aid or a vector of infection? J Hosp Infect. 2009;73:58–63
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8. Sanders DL, Kingsnorth AN, Lambie J, Bond P, Moate R, Steer JA. An experimental study exploring the relationship between the size of bacterial inoculum and bacterial adherence to prosthetic mesh. Surg Endosc. 2013;27:978–85
© 2014 International Anesthesia Research Society