Air Contamination in Operating Theatres: The Key Factors That Can Influence It

Objectives: Adequate ventilation and air filtration in the operating theatre are essential measures to prevent surgical site infections, which impact on hospital stay, healthcare costs and increased risk of mortality. The aim of the study is to assess how other factors, such as the number of operators and the opening of doors during surgery, affect microbiological airborne contamination. Methods: The data were extrapolated from 105 reports of operational controls conducted in the operating rooms in Siena's Teaching Hospital, Italy, from 2018 to 2021. The number of colonies incubated at 22°C and 36°C, was related by Spearman correlation analysis to the number of operators in the rooms and the number of air changes. The Mann-Whitney test was used to assess the difference between the mean of colonies detected with doors closed and opened. Results: The number of colonies incubated at 22°C was correlated only with air changes (Spearman ρ = -0.441; p < 0.001). In contrast, those incubated at 36°C were correlated with air changes (ρ = -0.394; p < 0.001) and the number of operators (ρ = +0.249; p=0.011). For colonies incubated at 22°C, the mean difference between opened and closed doors was not statistically significant (p=0.575). In contrast, the difference was statistically significant for those incubated at 36°C (p=0.013). In terms of airflow, our study showed a statistically significant difference (p < 0.001) between laminar and turbulent flow rooms for both colonies. Conclusion: Continuous monitoring of airflows, correlated with door opening and closing and the number of operators, can help predict levels of microbiological air contamination and thus prevent surgical infections.