Non-Invasive Ventilation: Implications on the Optimal Choice of Respiratory Protection

The guidance on the optimal choice of respiratory protection for healthcare workers (HCWs) caring for patients with suspected/confirmed influenza infection requiring non-invasive ventilation (NIV) has remained controversial. In a poster presentation at the International Conference on Prevention & Infection Control (ICPIC) held in Geneva, Switzerland from June 29 through July 2, 2011, researchers from the Prince of Wales Hospital in Hong Kong, report on their investigation of an influenza A outbreak involving three HCWs in a medical ward in July 2009. Contact tracing and viral studies were performed to identify the source of outbreak.

Three HCWs (a nurse, an intern and a general services assistant (GSA)) reported fever and upper respiratory symptoms on July 13. Nasal/throat swabs confirmed influenza A infection. On contact tracing, all three reported contact history with two patients (Patient A and B) admitted to the ward on July 10 and 11, respectively, who were later diagnosed with influenza A. Patient A was on 2L/min O2 while Patient B developed respiratory failure requiring 100 percent O2 and was soon transferred to a side room and put on NIV. Virological investigations confirmed that Patient B and the three staffs had influenza A/H3 subtype infection, while Patient A had influenza A/H1 infection.

The nurse had cared for both patients, the intern had performed physical examination for both patients, and the GSA transported both patients to the isolation facilities. They reported good compliance to droplet precautions and hand hygiene and were wearing surgical mask but not mucosal protection during the care of both patients. These three were the only staff among 24 that reported working within close proximity (<1 meter) of Patient B while he was on NIV.

Wong, et al. concluded that Patient B was identified as the index case causing this outbreak of influenza A/H3 subtype. The reseasrchers add that droplet precaution and the use of surgical masks may not offer adequate respiratory protection to HCWs caring for patients on NIV.

Reference: Wong B, Lai R, Chan P and Lee N. A hospital outbreak of seasonal influenza involving three healthcare workers implications on the optimal choice of respiratory protection. Poster presentation at the International Conference on Prevention & Infection Control (ICPIC). BMC Proceedings 2011, 5(Suppl 6):P100doi:10.1186/1753-6561-5-S6-P100. http://www.biomedcentral.com/1753-6561/5/S6/P100