title: Tracheal tube obstruction in mechanically ventilated patients assessed by high-resolution computed tomography.
abstract: BACKGROUND
  Tracheal intubation compromises mucus clearance and secretions accumulate inside the tracheal tube (TT). The aim of this study was to evaluate with a novel methodology TT luminal obstruction in critically ill patients.
  
  
  METHODS
  This was a three-phase study: (1) the authors collected 20 TTs at extubation. High-resolution computed tomography (CT) was performed to determine cross-sectional area (CSA) and mucus distribution within the TT; (2) five TTs partially filled with silicone were used to correlate high-resolution CT results and increased airflow resistance; and (3) 20 chest CT scans of intubated patients were reviewed for detection of secretions in ventilated patients' TT.
  
  
  RESULTS
  Postextubation TTs showed a maximum CSA reduction of (mean±SD) 24.9±3.9% (range 3.3 to 71.2%) after a median intubation of 4.5 (interquartile range 2.5 to 6.5) days. CSA progressively decreased from oral to lung end of used TTs. The luminal volume of air was different between used and new TTs for all internal diameters (P<0.01 for new vs. used TTs for all studied internal diameters). The relationship between pressure drop and increasing airflow rates was nonlinear and depended on minimum CSA available to ventilation. Weak correlation was found between TT occlusion and days of intubation (R²=0.352, P=0.006). With standard clinical chest CT scans, 6 of 20 TTs showed measurable secretions with a CSA reduction of 24.0±3.9%.
  
  
  CONCLUSIONS
  TT luminal narrowing is a common finding and correlates with increased airflow resistance. The authors propose high-resolution CT as a novel technique to visualize and quantify secretions collected within the TT lumen.
authors.affiliation: From the Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts (C.M., R.P., A.P., R.M.K., L. Berra); School of Dentistry, West Virginia University, Morgantown, West Virginia (J.G.T.); Center for Clinical and Translational Metagenomics, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts (L. Bry, M.L.D., A.D.B.); Center for System Biology, Massachusetts General Hospital, Boston, Massachusetts (J.T., G.R.W., M.N.); Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts (J.B.A.); and Department of Respiratory Care, Massachusetts General Hospital, Boston, Massachusetts (R.M.K.).
authors.forename: Cristina
authors.initials: C
authors.lastname: Mietto
authors.forename: Riccardo
authors.initials: R
authors.lastname: Pinciroli
authors.forename: Annop
authors.initials: A
authors.lastname: Piriyapatsom
authors.forename: John G
authors.initials: JG
authors.lastname: Thomas
authors.forename: Lynn
authors.initials: L
authors.lastname: Bry
authors.forename: Mary L
authors.initials: ML
authors.lastname: Delaney
authors.forename: Andrea
authors.initials: A
authors.lastname: Du Bois
authors.forename: Jessica
authors.initials: J
authors.lastname: Truelove
authors.forename: Jeanne B
authors.initials: JB
authors.lastname: Ackman
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Wojtkiewicz
authors.forename: Matthias
authors.initials: M
authors.lastname: Nahrendorf
authors.forename: Robert M
authors.initials: RM
authors.lastname: Kacmarek
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Berra
mesh_terms: D000399:Air Pressure; D060666:Airway Extubation; D000403:Airway Resistance; D019412:Anatomy, Cross-Sectional; D016638:Critical Illness; D004866:Equipment Contamination; D004868:Equipment Failure; D006801:Humans; D007442:Intubation, Intratracheal / Q000009:adverse effects* / Q000295:instrumentation; D008953:Models, Anatomic; D012121:Respiration, Artificial / Q000379:methods*; D014057:Tomography, X-Ray Computed; D014132:Trachea / Q000000981:diagnostic imaging* / Q000382:microbiology