Original contribution
Airborne bacterial contamination during orthopedic surgery: A randomized controlled pilot trial

https://doi.org/10.1016/j.jclinane.2017.02.008Get rights and content

Highlights

  • Airborne bacterial deposition in the OR has multiple potential causes.

  • Important causes for bacterial deposition were analyzed in a multivariate model.

  • The type of patient warming did not influence bacterial deposition.

  • Laminar airflow and shorter surgery time reduced airborne contamination.

Abstract

Study objective

Several factors such as lack of unidirectional, turbulent free laminar airflow, duration of surgery, patient warming system, or the number of health professionals in the OR have been shown or suspected to increase the number of airborne bacteria. The objective of this study was to perform a multivariate analysis of bacterial counts in the OR in patients during minor orthopedic surgery.

Design

Prospective, randomized pilot study.

Setting

Medical University of Vienna, Austria.

Patients

Eighty patients undergoing minor orthopedic surgery were included in the study.

Interventions

Surgery took place in ORs with and without a unidirectional turbulent free laminar airflow system, patients were randomized to warming with a forced air or an electric warming system.

Measurement

The number of airborne bacteria was measured using sedimentation agar plates and nitrocellulose membranes at 6 standardized locations in the OR.

Main results

The results of the multivariate analysis showed, that the absence of unidirectional turbulent free laminar airflow and longer duration of surgery increased bacterial counts significantly. The type of patient warming system and the number of health professionals had no significant influence on bacterial counts on any sampling site.

Conclusion

ORs with unidirectional turbulent free laminar airflow, and a reduction of surgery time decreased the number of viable airborne bacteria. These factors may be particularly important in critical patients with a high risk for the development of surgical site infections.

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.

References (30)

  • M. Pokrywka et al.

    Traffic in the operating room: a review of factors influencing air flow and surgical wound contamination

    Infect Disord Drug Targets

    (2013)
  • O.M. Lidwell et al.

    Ultraclean air and antibiotics for prevention of postoperative infection. A multicenter study of 8052 joint replacement operations

    Acta Orthop Scand

    (1987)
  • O.M. Lidwell et al.

    Effect of ultraclean air in operating rooms on deep sepsis in the joint after total hip or knee replacement: a randomised study

    Br Med J (Clin Res Ed)

    (1982)
  • C.A. Willis-Owen et al.

    Factors affecting the incidence of infection in hip and knee replacement: an analysis of 5277 cases

    J Bone Joint Surg (Br)

    (2010)
  • G. Peersman et al.

    Prolonged operative time correlates with increased infection rate after total knee arthroplasty

    HSS J

    (2006)
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