title: Volumetric analysis of aeration in the lungs during general anaesthesia.
abstract: Spiral computed tomography (CT) allows volumetric analysis of formation of atelectasis and aeration of the lungs during anaesthesia. We studied 26 premedicated patients undergoing elective surgery allocated to group 1 (conscious, spontaneous breathing, investigating inspiration and expiration), group 2 (general anaesthesia with mechanical ventilation, investigating inspiration and expiration) or group 3 (general anaesthesia with mechanical ventilation, investigating changes over time). Using spiral CT, the lungs were studied either before or during general anaesthesia. CT scans were grouped into the following areas: overaeration, normal aeration, reduced aeration, poor aeration and atelectasis. The mechanism of atelectasis appeared to be both gravitational forces and a diaphragm-related force that acts regionally in caudal lung regions. Mean atelectasis formation and poorly aerated regions comprised approximately 4% of the total lung volume between the diaphragm and carina, giving a mean value of 16-20% of the normal aerated lung tissue being either collapsed or poorly aerated. The vertical ventilation distribution was more even during anaesthesia than in the awake state.
authors.affiliation: Department of Anaesthesiology and Intensive Care, University Hospital, Uppsala, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Reber
authors.forename: G
authors.initials: G
authors.lastname: Engberg
authors.forename: B
authors.initials: B
authors.lastname: Sporre
authors.forename: L
authors.initials: L
authors.lastname: Kviele
authors.forename: H U
authors.initials: HU
authors.lastname: Rothen
authors.forename: G
authors.initials: G
authors.lastname: Wegenius
authors.forename: U
authors.initials: U
authors.lastname: Nylund
authors.forename: G
authors.initials: G
authors.lastname: Hedenstierna
mesh_terms: D000768:Anesthesia, General; D005260:Female; D006801:Humans; D008168:Lung / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D001261:Pulmonary Atelectasis / Q000000981:diagnostic imaging / Q000209:etiology; D012123:Pulmonary Ventilation / Q000502:physiology*; D012121:Respiration, Artificial; D014057:Tomography, X-Ray Computed / Q000379:methods*