title: The deep sulcus sign indicates free air in the abdomen.
authors.affiliation: Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Sheng-Huei
authors.initials: SH
authors.lastname: Wang
authors.affiliation: Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Kuang-Yu
authors.initials: KY
authors.lastname: Wei
authors.affiliation: Department of Anesthesiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Yao-Chia
authors.initials: YC
authors.lastname: Liu
authors.affiliation: Division of Pulmonary Medicine, Department of Internal Medicine, Tri-service General Hospital Songshan Branch, Taipei, Taiwan, ROC. slider4520@icloud.com.
authors.forename: Chao-Hsin
authors.initials: CH
authors.lastname: Huang
mesh_terms: D000369:Aged, 80 and over; D006801:Humans; D008297:Male; D011030:Pneumothorax / Q000000981:diagnostic imaging*