title: Noninvasive mechanical ventilation with average volume assured pressure support (AVAPS) in patients with chronic obstructive pulmonary disease and hypercapnic encephalopathy.
abstract: BACKGROUND
  Non-invasive mechanical ventilation (NIV) in patients with acute respiratory failure has been traditionally determined based on clinical assessment and changes in blood gases, with NIV support pressures manually adjusted by an operator. Bilevel positive airway pressure-spontaneous/timed (BiPAP S/T) with average volume assured pressure support (AVAPS) uses a fixed tidal volume that automatically adjusts to a patient's needs. Our study assessed the use of BiPAP S/T with AVAPS in patients with chronic obstructive pulmonary disease (COPD) and hypercapnic encephalopathy as compared to BiPAP S/T alone, upon immediate arrival in the Emergency-ICU.
  
  
  METHODS
  We carried out a prospective interventional match-controlled study in Guayaquil, Ecuador. A total of 22 patients were analyzed. Eleven with COPD exacerbations and hypercapnic encephalopathy with a Glasgow Coma Scale (GCS) <10 and a pH of 7.25-7.35 were assigned to receive NIV via BiPAP S/T with AVAPS. Eleven patients were selected as paired controls for the initial group by physicians who were unfamiliar with our study, and these patients were administered BiPAP S/T. Arterial blood gases, GCS, vital signs, and ventilatory parameters were then measured and compared between the two groups.
  
  
  RESULTS
  We observed statistically significant differences in favor of the BiPAP S/T + AVAPS group in GCS (P = .00001), pCO(2) (P = .03) and maximum inspiratory positive airway pressure (IPAP) (P = .005), among others. However, no significant differences in terms of length of stay or days on NIV were observed.
  
  
  CONCLUSIONS
  BiPAP S/T with AVAPS facilitates rapid recovery of consciousness when compared to traditional BiPAP S/T in patients with chronic obstructive pulmonary disease and hypercapnic encephalopathy.
  
  
  BACKGROUND
  Current Controlled Trials application ref is ISRCTN05135218.
authors.affiliation: Pulmonology Department, Military Hospital, Guayaquil, Ecuador. kyllenbrio@yahoo.com
authors.forename: Killen Harold
authors.initials: KH
authors.lastname: Briones Claudett
authors.forename: Monica
authors.initials: M
authors.lastname: Briones Claudett
authors.forename: Miguel
authors.initials: M
authors.lastname: Chung Sang Wong
authors.forename: Alberto
authors.initials: A
authors.lastname: Nuques Martinez
authors.forename: Ricardo
authors.initials: R
authors.lastname: Soto Espinoza
authors.forename: Mayra
authors.initials: M
authors.lastname: Montalvo
authors.forename: Antonio
authors.initials: A
authors.lastname: Esquinas Rodriguez
authors.forename: Gumersindo
authors.initials: G
authors.lastname: Gonzalez Diaz
authors.forename: Michelle
authors.initials: M
authors.lastname: Grunauer Andrade
mesh_terms: D018806:APACHE; D000368:Aged; D000369:Aged, 80 and over; D003422:Critical Care / Q000379:methods; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D006935:Hypercapnia / Q000628:therapy*; D007391:International Cooperation; D007902:Length of Stay; D008297:Male; D063087:Noninvasive Ventilation / Q000379:methods*; D011175:Positive-Pressure Respiration / Q000379:methods*; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000628:therapy*; D012131:Respiratory Insufficiency / Q000628:therapy*; D014474:Unconsciousness / Q000628:therapy*