title: Effects of acute on chronic respiratory failure on hypercapnia and 3-month survival.
abstract: BACKGROUND
  There is a lack of information on respiratory function and mechanics after COPD exacerbations.
  
  
  OBJECTIVE
  To find their role in short-term survival and occurrence of chronic hypercapnia after these events.
  
  
  METHODS
  Seventy-three COPD patients recovering from a recent severe exacerbation underwent evaluation of breathing pattern, breathing mechanics, lung function, and arterial blood gas levels at the time of discharge from a respiratory ICU (RICU).
  
  
  RESULTS
  The 3-month mortality rate after RICU discharge was 11%. The percent of ideal body weight (%IBW) [R = 6.04; p = 0.01] and occlusion pressure (R = 5.41; p = 0.02) provided significant distinction between deceased patients and survivors; the final discriminant equation showed that %IBW was able to predict patient death or survival with an accuracy of 90%. With decreasing order of power, the ratio of inspiratory time to total breathing cycle time (Ti/Ttot) [R = 8.87; p = 0.003], pressure-time product of the inspiratory muscles (R = 7.12; p = 0.009), maximal esophageal pressure (R = 6.00; p = 0.01), esophageal pressure (R = 5.50; p = 0.02), Pa(O2)/fraction of inspired oxygen (R = 4.72; p = 0.03), and pressure time index (PTI) [R = 4.57; p = 0.03] provided a significant distinction between hypercapnia and normocapnia at discharge. The discriminant equation, including Ti/Ttot and PTI, could correctly separate hypercapnic or normocapnic patients with an accuracy of 76%.
  
  
  CONCLUSIONS
  In COPD patients who are recovering from a severe exacerbation, hypercapnia is strongly related to inspiratory muscle work, strength, and breathing pattern; and only body weight predicts short-term survival.
authors.affiliation: Respiratory Department, Salvatore Maugeri Foundation, Istituto di Ricovero e Cura a Carattere Scientifico, Scientific Institute of Gussago, Via Pinidolo 23, 25064 Gussago (BS), Italy. mvitacca@fsm.it
authors.forename: Michele
authors.initials: M
authors.lastname: Vitacca
authors.forename: Luca
authors.initials: L
authors.lastname: Bianchi
authors.forename: Luca
authors.initials: L
authors.lastname: Barbano
authors.forename: Mara
authors.initials: M
authors.lastname: Ziliani
authors.forename: Nicolino
authors.initials: N
authors.lastname: Ambrosino
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D001835:Body Weight; D002908:Chronic Disease; D006801:Humans; D006935:Hypercapnia / Q000209:etiology / Q000401:mortality* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012008:Recurrence; D012129:Respiratory Function Tests; D012131:Respiratory Insufficiency / Q000150:complications / Q000401:mortality* / Q000503:physiopathology; D015656:Respiratory Mechanics / Q000502:physiology*; D016019:Survival Analysis