title: Microbial airway colonization is associated with noninvasive ventilation failure in exacerbation of chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  Abnormal airway colonization in patients with chronic obstructive pulmonary disease (COPD) needing invasive mechanical ventilation (IMV) is considered a first step in the acquisition of nosocomial pneumonia. Noninvasive ventilation (NIV) could potentially avoid this, but airway colonization has not been studied in patients who undergo NIV. We hypothesized that patients undergoing NIV would have lower rates of colonization than patients undergoing IMV. The aim of the study was to assess the microbial airway colonization in patients with exacerbated COPD needing NIV and IMV.
  
  
  METHODS
  A 2-yr prospective cohort study.
  
  
  METHODS
  Respiratory intensive and intermediate care unit.
  
  
  METHODS
  Eighty-six patients with exacerbated COPD undergoing NIV on admission (64 successes and 22 failures, according to subsequent intubation), and 51 patients undergoing IMV on admission.
  
  
  METHODS
  Quantitative culture specimens of sputum or tracheal aspirate were collected on admission and at follow-up (day 3) during NIV or IMV, respectively. Clinical assessment, including severity scores, and arterial blood gas measurements were also determined.
  
  
  RESULTS
  Compared with the NIV-success group, colonization by potentially pathogenic microorganisms was greater in the NIV-failure group on admission (13 [59%] vs. 14 [22%]; p < .001) and at follow-up while patients still underwent NIV (14 [93%] vs. 7 [14%]; p < .001), and it was even higher than during IMV at follow-up (20 [50%]; p = .027). Colonization by nonfermenting Gram-negative bacilli, mainly Pseudomonas aeruginosa, was significantly associated with NIV failure on admission (OR, 5.6; p = .016) and at follow-up (OR, 23.5; p < .001). Moreover, colonization by these microorganisms at follow-up (OR, 8.8; p = .008) and inadequate antimicrobial treatment (OR 11.3; p = .001) were associated with increased hospital mortality.
  
  
  CONCLUSIONS
  Airway colonization by nonfermenting Gram-negative bacilli is strongly associated with NIV failure. Because it occurs before intubation, this would be a marker rather than just a consequence of NIV failure necessitating intubation. The efficacy of decreasing airway colonization in preventing NIV failure needs to be assessed.
authors.affiliation: Servei de Pneumologia, Unitat de Cures Intensives i Intermèdies, Hospital Clinic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain. miferrer@clinic.ub.es
authors.forename: Miquel
authors.initials: M
authors.lastname: Ferrer
authors.forename: Malina
authors.initials: M
authors.lastname: Ioanas
authors.forename: Francisco
authors.initials: F
authors.lastname: Arancibia
authors.forename: Maria Angeles
authors.initials: MA
authors.lastname: Marco
authors.forename: Jorge Puig
authors.initials: JP
authors.lastname: de la Bellacasa
authors.forename: Antoni
authors.initials: A
authors.lastname: Torres
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003428:Cross Infection; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006801:Humans; D008297:Male; D018410:Pneumonia, Bacterial / Q000209:etiology; D011379:Prognosis; D011446:Prospective Studies; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D029424:Pulmonary Disease, Chronic Obstructive / Q000382:microbiology / Q000401:mortality / Q000503:physiopathology*; D012121:Respiration, Artificial / Q000379:methods; D012137:Respiratory System / Q000382:microbiology*; D013183:Sputum / Q000382:microbiology; D014132:Trachea / Q000382:microbiology