RESULTS: Since 12/19/13, there have been 12 #pulmcc Twitter chats; 6 have been on Critical Care related topics (End-of-life, ICU resource utilitization, Acute Respiratory Distress Syndrome, Sepsis, Ultrasound, and Big data), 4 on Pulmonary/Sleep related topics (Asthma, Idiopathic pulmonary fibrosis, Sarcoidosis, and Obstructive sleep apnea), and 2 conducted during the CHEST annual meeting on more general topics (Live-Tweeting Conferences, and Impact of disease on patients and families). During these one-hour Twitter chats there were a total of 4212 tweets by 418 participants resulting in 9,361,519 impressions. 75 of these participants participated in 2 or more #pulmcc Twitter chats. When comparing the number of participants, tweets and impressions between the Critical Care Twitter chats, the Pulmonary/Sleep Twitter chats, and the more general topics conducted during the CHEST annual meeting, we found that there were similar numbers of participants and tweets between the 3 different types of Twitter chats. Critical Care Twitter chats had 52 ± 17 participants and 422 ± 57 tweets, compared to 40 ± 10 participants and 272 ± 108 tweets in the Pulmonary/Sleep Twitter chats, and 56 ± 1 participants and 379 ± 98 tweets in the CHEST meeting Twitter chats (p=0.33 and p=0.28 respectively). However, there were significantly more repeat participants in the Critical Care chats (35% ± 4%) compared to the Pulmonary/Sleep chats and more general chats (23% ± 6% and 26% ± 5% respectively, p=0.01). There was also a significantly greater reach of the #pulmcc hashtag during the more general Twitter chats conducted at the CHEST annual meeting with 1,596,013 ± 126,472 impressions at these chats, compared to 739,203 ± 73,109 impressions during the Critical Care Twitter chats and 621,965± 123,933 impressions in the Pulmonary/Sleep chats (p=0.003).