Following tracheal intubation, mucus flow is reversed in the semirecumbent position

Possible role in the pathogenesis of ventilator-associated pneumonia

Gianluigi Li Bassi, Alberto Zanella, Massimo Cressoni, Mario Stylianou, Theodor Kolobow

Research output: Contribution to journalArticle

81 Citations (Scopus)

Abstract

OBJECTIVES: Critically ill intubated patients are positioned in the semirecumbent position to prevent pneumonia. In tracheally intubated sheep, we investigated the effects of gravitational force on tracheal mucus transport and on bacterial colonization of the respiratory system. DESIGN: Prospective randomized animal study. SETTING: Animal research facility at the National Institutes of Health. SUBJECTS: Sixteen healthy sheep. INTERVENTIONS: Spontaneously breathing or mechanically ventilated sheep were randomized to be positioned with the orientation of the trachea above (40 degrees, trachea-up) or below (5 degrees, trachea-down) horizontal. MEASUREMENTS AND MAIN RESULTS: Tracheal mucus velocity was measured through radiographic tracking of radiopaque tantalum disks, insufflated into the trachea. After 24 hrs, sheep were euthanized, and samples from the airways and lungs were taken for microbiological analysis. The proximal trachea was colonized in all sheep. In trachea-down sheep, all mucus moved toward the glottis at a mean velocity of 2.1 ± 1.1 mm/min. When mucus reached the endotracheal tube, it either entered the endotracheal tube or was lodged at the inflated endotracheal tube cuff. In all trachea-up sheep, abnormal tracheal mucus clearance was found. Mucus, mostly on the nondependent part of the trachea, moved toward the glottis at an average velocity of 2.2 ± 2.0 mm/min and constantly accumulated at the inflated endotracheal tube cuff. From the proximal trachea, mucus eventually moved toward the lungs on the dependent part of the trachea, leading to an "intratracheal route" of colonization of the lungs.Pneumonia was found in 6/8 of trachea-up sheep and the same microorganisms were isolated from the lungs and the proximal trachea. No pneumonia was found in trachea-down sheep (p = .007). CONCLUSIONS: The study indicates that following tracheal intubation gravitational force influences tracheal mucus clearance. When the trachea is oriented above horizontal, a flow of mucus from the proximal trachea toward the lungs is highly associated with bacterial colonization of the airways and pneumonia.

Original languageEnglish
Pages (from-to)518-525
Number of pages8
JournalCritical Care Medicine
Volume36
Issue number2
DOIs
Publication statusPublished - Feb 2008

Fingerprint

Ventilator-Associated Pneumonia
Mucus
Trachea
Intubation
Sheep
Pneumonia
Lung
Glottis
Tantalum
National Institutes of Health (U.S.)
Critical Illness

Keywords

  • Aspiration pneumonia
  • Bacterial pneumonia
  • Endotracheal tube
  • Intensive care unit
  • Mucus transport

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine

Cite this

Following tracheal intubation, mucus flow is reversed in the semirecumbent position : Possible role in the pathogenesis of ventilator-associated pneumonia. / Bassi, Gianluigi Li; Zanella, Alberto; Cressoni, Massimo; Stylianou, Mario; Kolobow, Theodor.

In: Critical Care Medicine, Vol. 36, No. 2, 02.2008, p. 518-525.

Research output: Contribution to journalArticle

Bassi, Gianluigi Li ; Zanella, Alberto ; Cressoni, Massimo ; Stylianou, Mario ; Kolobow, Theodor. / Following tracheal intubation, mucus flow is reversed in the semirecumbent position : Possible role in the pathogenesis of ventilator-associated pneumonia. In: Critical Care Medicine. 2008 ; Vol. 36, No. 2. pp. 518-525.
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AU - Kolobow, Theodor

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N2 - OBJECTIVES: Critically ill intubated patients are positioned in the semirecumbent position to prevent pneumonia. In tracheally intubated sheep, we investigated the effects of gravitational force on tracheal mucus transport and on bacterial colonization of the respiratory system. DESIGN: Prospective randomized animal study. SETTING: Animal research facility at the National Institutes of Health. SUBJECTS: Sixteen healthy sheep. INTERVENTIONS: Spontaneously breathing or mechanically ventilated sheep were randomized to be positioned with the orientation of the trachea above (40 degrees, trachea-up) or below (5 degrees, trachea-down) horizontal. MEASUREMENTS AND MAIN RESULTS: Tracheal mucus velocity was measured through radiographic tracking of radiopaque tantalum disks, insufflated into the trachea. After 24 hrs, sheep were euthanized, and samples from the airways and lungs were taken for microbiological analysis. The proximal trachea was colonized in all sheep. In trachea-down sheep, all mucus moved toward the glottis at a mean velocity of 2.1 ± 1.1 mm/min. When mucus reached the endotracheal tube, it either entered the endotracheal tube or was lodged at the inflated endotracheal tube cuff. In all trachea-up sheep, abnormal tracheal mucus clearance was found. Mucus, mostly on the nondependent part of the trachea, moved toward the glottis at an average velocity of 2.2 ± 2.0 mm/min and constantly accumulated at the inflated endotracheal tube cuff. From the proximal trachea, mucus eventually moved toward the lungs on the dependent part of the trachea, leading to an "intratracheal route" of colonization of the lungs.Pneumonia was found in 6/8 of trachea-up sheep and the same microorganisms were isolated from the lungs and the proximal trachea. No pneumonia was found in trachea-down sheep (p = .007). CONCLUSIONS: The study indicates that following tracheal intubation gravitational force influences tracheal mucus clearance. When the trachea is oriented above horizontal, a flow of mucus from the proximal trachea toward the lungs is highly associated with bacterial colonization of the airways and pneumonia.

AB - OBJECTIVES: Critically ill intubated patients are positioned in the semirecumbent position to prevent pneumonia. In tracheally intubated sheep, we investigated the effects of gravitational force on tracheal mucus transport and on bacterial colonization of the respiratory system. DESIGN: Prospective randomized animal study. SETTING: Animal research facility at the National Institutes of Health. SUBJECTS: Sixteen healthy sheep. INTERVENTIONS: Spontaneously breathing or mechanically ventilated sheep were randomized to be positioned with the orientation of the trachea above (40 degrees, trachea-up) or below (5 degrees, trachea-down) horizontal. MEASUREMENTS AND MAIN RESULTS: Tracheal mucus velocity was measured through radiographic tracking of radiopaque tantalum disks, insufflated into the trachea. After 24 hrs, sheep were euthanized, and samples from the airways and lungs were taken for microbiological analysis. The proximal trachea was colonized in all sheep. In trachea-down sheep, all mucus moved toward the glottis at a mean velocity of 2.1 ± 1.1 mm/min. When mucus reached the endotracheal tube, it either entered the endotracheal tube or was lodged at the inflated endotracheal tube cuff. In all trachea-up sheep, abnormal tracheal mucus clearance was found. Mucus, mostly on the nondependent part of the trachea, moved toward the glottis at an average velocity of 2.2 ± 2.0 mm/min and constantly accumulated at the inflated endotracheal tube cuff. From the proximal trachea, mucus eventually moved toward the lungs on the dependent part of the trachea, leading to an "intratracheal route" of colonization of the lungs.Pneumonia was found in 6/8 of trachea-up sheep and the same microorganisms were isolated from the lungs and the proximal trachea. No pneumonia was found in trachea-down sheep (p = .007). CONCLUSIONS: The study indicates that following tracheal intubation gravitational force influences tracheal mucus clearance. When the trachea is oriented above horizontal, a flow of mucus from the proximal trachea toward the lungs is highly associated with bacterial colonization of the airways and pneumonia.

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