Abstract
In Operating Theatres (OT), the ventilation system plays an important role in controlling airborne contamination and reducing the risks of Surgical Site Infections (SSIs). The air cleanliness is really crucial in this field and different measurements are used in order to characterize the situation in terms of both airborne microbiological pollutants and particle size and concentration. Although the ventilation systems and airborne contamination are strictly linked, different air diffusion schemes (in particular, the Partial Unidirectional Airflow, P-UDAF, and the Mixing Airflow, MAF) and various design parameters are used, and there is still no consensus on real performance and optimum solutions. This study presents measurements procedures and results obtained during Inspection and Periodic Performance Testing (1228 observations) in a large sample of Italian OTs (175 OTs in 31 Italian hospitals) in their operative life (period from 2010 to 2018). The inspections were made after a cleaning procedure, both in “at-rest” conditions and “in operation” state. Inert and microbial contamination data (in air and on surfaces) are analyzed and commented according to four relevant air diffusion schemes and design classes. Related data on Recovery Time (RT) and personnel presence were picked up and are commented. The results confirm that the ventilation systems are able to maintain the targeted performance levels in the OT operative life. However, they attest that significant differences in real OT contamination control capabilities do exist and could be ascribed to various design choices and to different operation and maintenance practices. The study shows and confirms that the air diffusion scheme and the design airflow rate are critical factors. Beside large variations in measurements, the performance values, in terms of control of airborne particle and microbial contamination (in air and on surfaces), for P-UDAF systems are better than those that were assessed for the MAF air diffusion solution. The average performances do increase with increasing airflows, and the results offer a better insight on this relationship leading to some possible optimization.
Highlights
Surgery operations are one of the most vulnerable procedures for infections in operating theatres.It is known that patients with low immune protection are prone to infections
In addition to the numerous studies conducted on ventilation efficiency, Operating Theatres (OT) performance is often evaluated in terms of microbiological and inert contamination of air and surfaces [44,45] according to the guidelines and to the limit values used in cleanroom environments for pharmaceutical production
The results confirm that, in general, the ventilation systems are able to obtain and maintain in their lifetime the intended cleanliness performance levels. They attest that significant differences in real OT contamination control capabilities do exist and they could be ascribed to many design choices and different operation and maintenance practices
Summary
Surgery operations are one of the most vulnerable procedures for infections in operating theatres. The relationship between wound infection and airborne contamination has been studied since the 1940s [12,13,14,15,16], with increasing interest on the analysis of operating theatres with different types of ventilation systems, on the effect on cross-contamination, and on viable airborne reduction [17] Based on those studies, two main types of ventilation for OT environments have been identified: mixing ventilation airflow (MAF) and partial unidirectional airflow (P-UDAF). In addition to the numerous studies conducted on ventilation efficiency, OT performance is often evaluated in terms of microbiological and inert contamination of air and surfaces [44,45] according to the guidelines and to the limit values used in cleanroom environments for pharmaceutical production These environments conform to Good Manufacturing Practice Guidelines (GMPs) and ISO 14644:1 standards or national guidelines [46,47,48] and they are classified “at-rest” and “in operation” occupancy states. The knowledge gained by this study on contamination control in OTs can help hospitals and engineers to select and operate OT ventilation systems and OT procedures properly, ensuring low contamination levels, low infection rates, and safer working conditions
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