Original contributionAirborne bacterial contamination during orthopedic surgery: A randomized controlled pilot trial
Introduction
Surgical site infections (SSIs) are among the most severe complications in orthopedic and trauma surgery and have a serious impact on patient morbidity and mortality. Despite strict perioperative hygiene standards the incidence of postoperative orthopedic wound infections is still high ranging between 0.1% to 12% [1], [2], [3].
The infected surgical wound is usually colonized by commensal bacteria originating from the patient's own skin (endogenous) or exogenously by bacteria airborne in the operating room (OR). While there is general agreement on the protective effect of adequate skin antisepsis on the rate of SSIs, strategies to reduce airborne contamination are still disputed. One possibility for reducing airborne contamination is the use of a unidirectional turbulent free laminar airflow ventilation system (laminar airflow). Surprisingly, while the benefit of laminar airflow systems seems intuitive, evidence to implement laminar airflow as a standard requirement for every OR is contradictory [4], [5]. As laminar airflow is costly and conclusive evidence is lacking, many hospital administrators hesitate to implement laminar airflow technologies in their ORs. In the US only 30% of 256 hospitals in 4 US states reported the regular use of laminar airflow in 2005 [6].
However, also other factors such as duration of surgery, number of OR staff [7] and use of forced air patient warming [8] might influence airborne bacterial displacement and could blur eventual beneficial effects of laminar airflow.
The aim of the study was thus to determine the influence of four intraoperative factors – use of laminar airflow, duration of surgery, number of health professionals present and use of forced air - on airborne bacterial contamination, measured by 6 sedimentation plates at standardized locations in the OR including two locations on the instrument table.
Section snippets
Materials and methods
The study was approved by the Ethics Committee of the Medical University of Vienna and patients' written, informed consent was obtained in all patients undergoing minor orthopedic interventions either the day before surgery or on the day of surgery, if the patient had not been admitted to the hospital on the day before surgery, from January 2009 to June 2009. A manuscript using the same study patients' data as this paper demonstrated that different laminar airflow sizes affected the bacterial
Statistical analysis
All values are displayed as means ± standard deviation, median (25th–75th quartile) or frequency (%), as appropriate. Plates 5 and 6 were averaged before analysis. Sample size was estimated with bacterial growth on the instrument table plates (mean of plates 5 & 6) as primary outcome. With an alpha error of 0.05, a power of 0.8 and an effect size of 0.7 for difference of airborne contamination by non-forced air warming versus forced air warming, 40 patients per group were calculated for a
Results
All patients completed the study. The average age of patients was 43 ± 15 years, with a weight of 78 ± 15 kg and a height of 174 ± 9 cm. 44 male (55%) and 36 female (45%) patients were included (see Fig. 1). Details about surgical interventions, number of health professionals present, duration of surgery, the use of forced air or electric blanket warming and laminar airflow are displayed in Table 1.
There was no difference for bacterial growth on the mean of plates 5 & 6 between the forced air and the
Discussion
In the present study we found, that the absence of laminar airflow and a longer duration of surgery increased airborne bacteria in the OR. In patients with a high risk for surgical wound infections, optimization of these factors may be an important preventive measure.
Despite being widely used the benefits of laminar airflow environments in ORs are still disputed. While the concept of clean, laminar flowing air to avoid SSIs is plausible and supported by some studies, other authors disagree as
Disclosures and funding
All funding was provided by the Medical University of Vienna.
Conflict of interest
Oliver Kimberger has received financial support for studies and travel costs and fees for speaker assignments from the following companies producing patient temperature management products: Biegler GmbH, Mauerbach, Austria; Augustine Biomedical, Eden Prairie, MN, USA; Möck&Möck, Hamburg, Germany; Zoll, USA; Zoll, San Jose, CA, USA; 3 M, St. Paul, MN, USA; Dräger AG, Lübeck, Germany; 3M, St. Paul, MN, USA; The 37 Company, Amersfoort, the Netherlands.
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