What is the primary rationale for designing an operating room with positive-pressure ventilation?

• A. To limit entry of contaminants from surrounding areas
• B. To reduce humidity
• C. To increase noise
• D. To minimize energy use

Answer: (A)

Positive-pressure ventilation in an operating room is used to protect the sterile field by making air move outward from the room to surrounding areas. Because the room is kept at a higher pressure than adjacent spaces, any door opening or small gap tends to push air out rather than pull in air from the hallway. This outward flow helps prevent contaminants from entering the room, reducing the risk of introducing dust, skin flakes, or microbes to the surgical field and patient. Humidity control, noise, and energy use are important considerations in OR design, but they are not the primary reason for using positive pressure.