title: Effects of tracheal orientation on development of ventilator-associated pneumonia: an experimental study.
abstract: OBJECTIVE
  Orientation of the trachea and tracheal tube below horizontal may prevent aspiration of oropharyngeal secretions into the lungs, which is a pivotal pathway in the pathogenesis of ventilator-associated pneumonia (VAP). The incidence of VAP was evaluated in swine with orientation of trachea and tracheal tube above horizontal (model of semirecumbent position, currently recommended in patients) and below horizontal.
  
  
  METHODS
  Twenty-six mini-pigs were randomized into four groups: (A) eight mechanically ventilated with orientation of trachea 45° above horizontal for 72 h. In the remaining groups (B, C, D) the trachea was oriented 10° below horizontal, with (B) six mechanically ventilated for 72 h, (C) six mechanically ventilated for 72 h with enteral feeding, and (D) six mechanically ventilated for 168 h with enteral feeding. At the end of the study period, all pigs were sacrificed and the clinical diagnosis of VAP was microbiologically evaluated. No antibiotics were administered.
  
  
  RESULTS
  All eight pigs kept orientated with the trachea 45° above horizontal developed VAP and respiratory failure (PaO(2)/F(i)O(2) = 132 ± 139 mmHg) with a median of 5.5 pulmonary lobes out of 6 colonized with average colonization of 9.3 × 10(7) CFU/g. None of the 18 pigs kept oriented with the trachea below horizontal developed VAP; 16 had sterile lungs, while 2, ventilated for 7 days, developed a low level of colonization.
  
  
  CONCLUSIONS
  Orientation of the trachea above horizontal was uniformly associated with VAP and respiratory failure; positioning the trachea below horizontal consistently prevented development of VAP.
authors.affiliation: National Institutes of Health, National Heart, Lung, and Blood Institute, Section of Pulmonary and Cardiac Assist Devices, Pulmonary and Critical Care Medicine Branch, Bethesda, MD 20892, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Zanella
authors.forename: Massimo
authors.initials: M
authors.lastname: Cressoni
authors.forename: Myra
authors.initials: M
authors.lastname: Epp
authors.forename: Viktoria
authors.initials: V
authors.lastname: Hoffmann
authors.forename: Mario
authors.initials: M
authors.lastname: Stylianou
authors.forename: Theodor
authors.initials: T
authors.lastname: Kolobow
mesh_terms: D000818:Animals; D005260:Female; D006439:Hemodynamics; D007442:Intubation, Intratracheal / Q000009:adverse effects / Q000379:methods*; D056888:Patient Positioning; D053717:Pneumonia, Ventilator-Associated / Q000209:etiology / Q000517:prevention & control*; D012121:Respiration, Artificial / Q000009:adverse effects / Q000379:methods*; D018709:Statistics, Nonparametric; D013552:Swine; D013556:Swine, Miniature; D014132:Trachea / Q000033:anatomy & histology*