EVALUATION OF ROOMS WITH NEGATIVE-PRESSURE VENTILATION USED FOR RESPIRATORY ISOLATION IN 7 MIDWESTERN HOSPITALS

OBJECTIVE: To determine the number and efficacy of respiratory isolati on facilities in St. Louis hospitals and to assess the mechanisms in p lace for evaluating function of hospital ventilation systems. DESIGN: A prospective multi-hospital surveillance study using direct observati on and a standardized questionnaire. SETTING: Seven hospitals (includi ng university-affiliated large teaching, private community, private te aching, and private nonteaching adult hospitals, and one pediatric tea ching hospital) in St. Louis, Missouri. MEASUREMENTS: Actual direction of airflow in rooms designated for respiratory isolation was measured using smokesticks. Hospital demographic information, respiratory isol ation policies, and frequency of ventilation tests were provided by in fection control personnel. RESULTS: One hundred twenty-one (3.4%) of 3 ,574 hospital rooms were designed to have negative pressure ventilatio n suitable for respiratory isolation. The percentage of isolation room s in each institution ranged from 0.4% (92 of 486) to 93% (39 of 42). Only three (43%) of seven hospitals had intensive care respiratory iso lation rooms, an none had isolation rooms in the emergency department. No hospital had tested routinely the efficacy of the negative pressur e ventilation, and two (28%) of seven had tested airflow for the first time in the past year. We tested 115 (95%) of 121 isolation rooms. Wi th the doors closed, 52 (45%) of 115 designated negative pressure room s actually had positive airflow to the corridor. The number of negativ e pressure rooms and die presence or absence of anterooms did not pred ict correct direction of airflow. There was a significant difference a mong hospitals in the percentage of designated isolation rooms that ha d truly negative pressure (P<0.0001). Hospital age, size, and type cor related with correct direction of airflow (P<0.0001). CONCLUSION. In t he hospitals studied, only a small number of rooms were designated for respiratory isolation, and the performance of these was not tested ro utinely. High-risk areas including intensive care units and emergency rooms were not equipped to provide respiratory isolation. The directio n of airflow in respiratory isolation rooms was not always correct and should be evaluated frequently.