title: Factors associated with noninvasive ventilation response in the first day of therapy in patients with hypercapnic respiratory failure.
abstract: OBJECTIVE
  Noninvasive ventilation (NIV) decreases mechanical ventilation indication in the early period of acute hypercapnic respiratory failure (AHcRF) and factors for success have been studied well. But, less is known about the factors influencing the NIV response in the subacute period. This study was aimed to determine the factors influencing the reduction of PaCO(2) levels within first 24 hours of therapy.
  
  
  METHODS
  NIV response was defined as reduction of PaCO(2) level below 50 mmHg within first 24 hours. Patients with AHcRF, treated with NIV, were divided into 2 groups according to this criterion; group 1 as the nonresponsive, group 2 as the responsive. The differences in NIV methods and characteristics of the two groups were evaluated and compared in this retrospective study.
  
  
  RESULTS
  A total of 100 patients were included in the study; 66 of them in group 1 and 34 in group 2. No significant differences were identified between the length of NIV application and intensive care unit (ICU) stay, intubation and mortality rates, across the groups. Ninety-one percent of the patients in group 2 had received all night long NIV therapy; this was just 74% in group 1 (P=0.036). Results of multivariate analysis showed that while nocturnal application was significantly associated with better response, prior home ventilation and requirement of higher pressure support (PS) levels significantly and independently associated with poorer response to NIV therapy.
  
  
  CONCLUSIONS
  In patients with AHcRF, all night long use of NIV may accelerate healing by improving PaCO(2) reduction within the first 24 hours. A rapid response in PaCO(2) levels should not be expected in patients requiring higher PS levels and using prior home ventilation.
authors.affiliation: Department of Pulmonary Critical Care Medicine, Gazi University School of Medicine, Ankara, Turkey.
authors.forename: Gul
authors.initials: G
authors.lastname: Gursel
authors.forename: Muge
authors.initials: M
authors.lastname: Aydogdu
authors.forename: Secil
authors.initials: S
authors.lastname: Tasyurek
authors.forename: Gazi
authors.initials: G
authors.lastname: Gulbas
authors.forename: Sevket
authors.initials: S
authors.lastname: Ozkaya
authors.forename: Sakine
authors.initials: S
authors.lastname: Nazik
authors.forename: Ayse
authors.initials: A
authors.lastname: Demir