Diagnosing pleural effusion: moving beyond transudate-exudate separation.

in our article, our human lung model simply reflected a baseline estimate of the distance traveled by any potentially infectious aerosols while the patient was breathing at rest with a respiratory rate of 12 breaths/min. With appropriate references,2,3 we have already stressed the importance of full personal protective equipment as an effective infection control measure in protecting health-care workers against severe acute respiratory syndrome.1 We are well aware of the possibility that viral infection such as severe acute respiratory syndrome has the potential of spreading by an airborne route, and indeed our institution has made a significant contribution to the literature on this issue.4,5 It is important for clinicians involved in the management of infectious diseases to understand that environmental factors such as medical ward airflow and ventilation may play a significant role in the aerosol transmission of infection in health-care premises.6 In addition to full personal protective equipment and good personal hygiene, the World Health Organization and the Centers for Disease Control and Prevention have recommended in influenza pandemic plans enhanced infection control precautions in health-care facilities, including placing patients with suspected and confirmed H5N1 influenza in negative-pressure isolation rooms with 6 to 12 air exchanges per hour (if available) due to the high lethality of the disease and uncertainty about the mode of human to human transmission.7,8 The negative-pressure room will reduce the spread of airborne contamination between rooms, and a recent study9 has shown that the air exchange rate and airflow patterns are important factors in the control of airborne virus infection, and good ventilation arrangement may enhance the safety of staff when performing medical treatments within isolation rooms.