title: Utility of respiratory ward-based NIV in acidotic hypercapnic respiratory failure.
abstract: OBJECTIVE
  We sought to elicit predictors of in-hospital mortality for first and subsequent admissions with acidotic hypercapnic respiratory failure (AHRF) in a cohort of chronic obstructive pulmonary disease patients who have undergone ward-based non-invasive ventilation (NIV), and identify features associated with long-term survival.
  
  
  METHODS
  Analysis of prospectively collected data at a single centre on patients undergoing NIV for AHRF between 2004 and 2009. Predictors of in-hospital mortality and intubation were sought by logistic regression and predictors of long-term survival by Cox regression.
  
  
  RESULTS
  Initial pH exhibited a threshold effect for in-hospital mortality at pH 7.15. This relationship remained in patients undergoing their first episode of AHRF. In both first and subsequent admissions, a pH threshold of 7.25 at 4 h was associated with better prognosis (P = 0.02 and P = 0.04 respectively). In second or subsequent episodes of AHRF, mortality was lower and predicted only by age (P = 0.002) on multivariate analysis.
  
  
  CONCLUSIONS
  NIV could be used on medical wards for patients with pH 7.16 or greater on their first admission, although more conservative values should continue to be used for those with a second or subsequent episodes of AHRF.
authors.affiliation: Academic Department of Sleep & Ventilation, Heart of England NHS Foundation Trust, University of Birmingham, Birmingham, UK.
authors.forename: Chirag
authors.initials: C
authors.lastname: Dave
authors.forename: Alice
authors.initials: A
authors.lastname: Turner
authors.forename: Ajit
authors.initials: A
authors.lastname: Thomas
authors.forename: Ben
authors.initials: B
authors.lastname: Beauchamp
authors.forename: Biman
authors.initials: B
authors.lastname: Chakraborty
authors.forename: Asad
authors.initials: A
authors.lastname: Ali
authors.forename: Rahul
authors.initials: R
authors.lastname: Mukherjee
authors.forename: Dev
authors.initials: D
authors.lastname: Banerjee
mesh_terms: D000142:Acidosis, Respiratory / Q000209:etiology / Q000503:physiopathology / Q000628:therapy; D000368:Aged; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D006935:Hypercapnia / Q000209:etiology / Q000503:physiopathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D063087:Noninvasive Ventilation / Q000379:methods / Q000706:statistics & numerical data; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000209:etiology / Q000401:mortality / Q000503:physiopathology; D006113:United Kingdom / Q000453:epidemiology
keywords: chronic obstructive pulmonary disease; exacerbation; non-invasive ventilation; rational use of resources; respiratory failure