Association between air changes and airborne microbial contamination in operating rooms

Area of Science:

• Healthcare-associated infection control
• Environmental microbiology
• Hospital engineering

Background:

• Operating room (OR) airborne microbial contamination poses a significant risk.
• Effective control strategies are essential for patient safety.
• Air turnover is a key factor in reducing contamination.

Purpose of the Study:

• To verify the association between air turnover and airborne contamination in ORs.
• To establish a statistical relationship between air turnover and microbial load.
• To inform guidelines for maintaining safe OR environments.

Main Methods:

• Cross-sectional study conducted in 19 ORs (laminar and turbulent flow) over 3 years.
• Air samples collected and analyzed for colony forming units (CFU).
• Log-linear regression used to model the relationship between air changes per hour (ACH) and CFU/m³.

Main Results:

• A statistically significant nonlinear association was found between ACH and CFU (p < 0.05).
• Log-linear regression models demonstrated a good fit for both laminar (R²=0.3911) and turbulent (R²=0.3443) flow systems.
• Specific regression parameters were estimated for each ventilation type.

Conclusions:

• The study quantifies the relationship between air changes per hour (ACH) and airborne microbial contamination (CFU) in ORs.
• The findings support the need for adequate air turnover to meet Italian microbial load limits.
• The developed model can be used to determine minimum ACH requirements for specific OR environments.