Effect of ventilation rate on the optimal air quality of trauma and colorectal operating rooms

No consistent standards exist for minimum air ventilation rates in operating rooms (ORs). This study conducted air quality monitoring of trauma and colorectal ORs to determine the minimum ventilation rates for optimal air quality. Four “class 10,000 (defined the maximum concentration of PM≥0.5 is 10,000 particles/ft3 or 352,000 particles/m3)” trauma and colorectal ORs in active use were selected as study locations. The air temperature, relative humidity, and concentrations of CO2, total volatile organic compounds (TVOCs), suspended particulate matter (PM), airborne bacteria, and settled bacteria were monitored with ventilation rates of 20, 25, and 30 air changes per hour (ACH) for 10 h. The electrocautery time, door opening frequency, door opening time, and number of people in the ORs were also recorded. The median concentrations of PM≥0.5 for all ventilation rates were 3.99 × 105–6.52 × 105 particles/m3 in the trauma ORs and 5.23 × 105–7.27 × 105 particles/m3 in the colorectal ORs. The trauma ORs at 20–30 ACH and colorectal ORs at 25–30 ACH complied with England's airborne bacterial concentration standard. An inverse relationship was found between ventilation rate and CO2, TVOCs, and airborne bacterial concentrations. A positive relationship was observed between electrocautery time and TVOCs concentration. The door opening time and number of people in the ORs impacted CO2, TVOCs, and PM concentrations. In conclusion, minimum ventilation rates may be set to 20 ACH for trauma ORs and 25 ACH for colorectal ORs. When the ventilation rate of an OR is increased, the CO2, TVOCs, and airborne bacterial levels are significantly reduced.