The content is available as a PDF (327.0 KB).
. 2016 Dec 15;194(12):P21–P22. doi: 10.1164/rccm.19412P21
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.