RT Journal Article SR Electronic T1 Measuring diaphragm shortening using ultrasonography to predict extubation success JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 402 OP 404 DO 10.1136/thoraxjnl-2013-204920 VO 69 IS 5 A1 Criner, Gerard J YR 2014 UL http://thorax.bmj.com/content/69/5/402.abstract AB