Negative pressure rooms

 Q: How frequently air should be changed in negative pressure rooms in ICU?

Answer:  6 to 12 air changes per hour 

Infected particles from respiratory secretions less than 5 microns can stay suspended in the air for a considerable period of time and may get inhaled by people in the surroundings. Airborne precautions are advised for infections like tuberculosis, measles, varicella, smallpox, and SARS viruses (including COVID-19). 

In ICUs airborne isolation is usually done in 'negative pressure rooms'. These rooms should have changed air for at least 6 to 12 times per hour. The door of the room needs to stay closed and caretakers should ideally be wearing N-95 masks. All healthcare workers should be tested for fitting their N-95 masks for a tight seal.

Said that, controversy does exist about negative pressure rooms' efficacy in protecting healthcare workers (see reference # 4).

#infectious-diseases 

Reference: 

1. Jensen PA, Lambert LA, Iademarco MF, et al. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings, 2005. MMWR Recomm Rep 2005; 54:1.  

2. Wilder-Smith A, Low JG. Risk of respiratory infections in health care workers: lessons on infection control emerge from the SARS outbreak. Southeast Asian J Trop Med Public Health 2005; 36:481. 

3. Miller SL, Clements N, Elliott SA, Subhash SS, Eagan A, Radonovich LJ. Implementing a negative-pressure isolation ward for a surge in airborne infectious patients. Am J Infect Control. 2017 Jun 1;45(6):652-659.  

4. Braude D, Femling J. Dangerous Misperceptions About Negative-Pressure Rooms. Ann Emerg Med. 2020;76(5):690. doi:10.1016/j.annemergmed.2020.05.036