RT Journal Article SR Electronic T1 Morphine in acute chronic obstructive pulmonary disease exacerbation JF BMJ Case Reports JO BMJ Case Reports FD BMJ Publishing Group Ltd SP e239739 DO 10.1136/bcr-2020-239739 VO 14 IS 4 A1 Toru Kadowaki A1 Shuichi Yano YR 2021 UL http://casereports.bmj.com/content/14/4/e239739.abstract AB