While most in-patient medical facilities contain a small number of isolation rooms for patients whose immune systems are compromised, the new 144-bed cancer treatment center at the City of Hope National Medical Center in Duarte, CA, designed by the architectural firm NBBJ (Seattle), is composed almost entirely of critical care/positive-pressure isolation rooms, used for patients undergoing such procedures as bone marrow transplants. Since immunosuppressed patients must be protected from infection, special design considerations and air circulation systems are required to ensure that they will be protected from this risk.
By their very nature, isolation rooms, otherwise known as protective environment rooms, imply a controlled environment. Rooms for patients who need protection against contaminants require positive air pressure relative to the adjoining spaces. No air must be allowed to enter from the outside; the only air permitted is that introduced through the air-handling system. Therefore, the supply, flow, and quality of air must be strictly controlled.