Abstract
Aim
The aim of this study was to assess the influence of the true operating room (OR) ventilation on the risk of revision due to infection after primary total hip arthroplasty (THA) reported to the Norwegian Arthroplasty Register (NAR).
Method
40 orthopedic units were included during the period 2005 – 2015. The Unidirectional airflow (UDAF) systems were subdivided into small-area, low-volume, vertical UDAF (lvUDAF) (volume flow rate (VFR) (m3/hour) <=10,000 and diffuser array size (DAS) (m2) <=10); large-area, high-volume, vertical UDAF (hvUDAF) (VFR >=10,000 and DAS >=10) and Horizontal UDAF (H-UDAF). The systems were compared to conventional, turbulent ventilation (CV) systems. The association between revision due to infection and OR ventilation was assessed using Cox regression models, with adjustments for sex, age, indication for surgery, ASA-classification, method of fixation, modularity of the components, duration of surgery, in addition to year of primary THA. All included THAs received systemic, antibiotic prophylaxis.
Results
51,292 primary THAs were eligible for assessment. 575 (1.1%) of these THAs had been revised due to infection. Compared to CV, there was similar risk of revision due to infection after THA performed in ORs with lvUDAF (RR=0.9, 95 % CI: 0.7–1.1) and with H-UDAF (RR=1.3, 95 % CI: 0.9–1.8). The risk of revision due to infection after THA performed in ORs with large-area hvUDAF-systems was lower (RR=0.8, 95% CI: 0.6–0.9, p=0.01) compared to CV.
Conclusions
This study indicates that large-area, high-volume, vertical UDAF systems may be superior to conventional ventilation systems as a prophylactic measure against THA infection. This emphasizes the importance of assessing the big diversity of different ventilation systems when studying effect measures.
