title: Predictors of failure of noninvasive ventilation in patients with severe community-acquired pneumonia.
abstract: OBJECTIVE
  The study aimed to investigate cardiorespiratory parameters potentially predictive of failure of noninvasive ventilation (NIV) in severe community-acquired pneumonia (CAP).
  
  
  METHODS
  Sixty-four consecutive patients with severe CAP entered the study and underwent NIV with a helmet. Arterial blood gases, Pao(2)/FIo(2), and oxygenation index (OI; mean airway pressure × FIo(2) × 100/Pao(2)) were determined before and after a 1-hour trial of NIV.
  
  
  RESULTS
  Noninvasive ventilation succeeded in 28 patients (43%) and failed in 36 patients (56%). Patients who avoided intubation had significantly (P < .05) shorter stays in ICU and lower rates of mortality in ICU and in hospital. Patients who failed NIV had higher Simplified Acute Physiology Score II at ICU admission (33 ± 11 versus 29 ± 9) and lower pH before NIV trial (7.37 versus 7.44). Furthermore, patients who required intubation failed to improve or worsened arterial blood gases during NIV trial and, by the end of the trial, had lower (P < .05) pH (7.34 versus 7.44) and Pao(2)/FiO(2) (177 versus 228) and higher OI (8.6 versus 5.0) and respiratory rate (28 versus 23 breaths/min). In a multivariate analysis, post-NIV to pre-NIV deltas of Pao(2)/FiO(2) and of OI were independent predictors of NIV failure, with OI delta being significantly more accurate.
  
  
  CONCLUSIONS
  Noninvasive ventilation failed in approximately half patients with severe CAP. Posttrial to pretrial deltas of Pao(2)/FiO(2) and OI may help to guide decision about endotracheal intubation.
authors.affiliation: Dipartimento di Farmacologia e Anestesiologia, Università di Padova, I-35121 Padova, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Carron
authors.forename: Ulderico
authors.initials: U
authors.lastname: Freo
authors.forename: Manuel
authors.initials: M
authors.lastname: Zorzi
authors.forename: Carlo
authors.initials: C
authors.lastname: Ori
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017714:Community-Acquired Infections / Q000097:blood / Q000628:therapy; D003422:Critical Care; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D011014:Pneumonia / Q000097:blood / Q000628:therapy*; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods*; D012720:Severity of Illness Index; D017211:Treatment Failure
chemical_list: D010100:Oxygen