title: Assessment of factors that influence weaning from long-term mechanical ventilation after cardiac surgery.
abstract: OBJECTIVE
  To analyze parameters of respiratory system mechanics and oxygenation and cardiovascular alterations involved in weaning tracheostomized patients from long-term mechanical ventilation after cardiac surgery.
  
  
  METHODS
  We studied 45 patients in their postoperative period of cardiac surgery, who required long-term mechanical ventilation for more than 10 days and had to undergo tracheostomy due to unsuccessful weaning from mechanical ventilation. The parameters of respiratory system mechanics, oxygenation and the following factors were analyzed: type of surgical procedure, presence of cardiac dysfunction, time of extracorporeal circulation, and presence of neurologic lesions.
  
  
  RESULTS
  Of the 45 patients studied, successful weaning from mechanical ventilation was achieved in 22 patients, while the procedure was unsuccessful in 23 patients. No statistically significant difference was observed between the groups in regard to static pulmonary compliance (p = 0.23), airway resistance (p = 0.21), and the dead space/tidal volume ratio (p = 0.54). No difference was also observed in regard to the variables PaO2/FiO2 ratio (p = 0.86), rapid and superficial respiration index (p = 0.48), and carbon dioxide arterial pressure (p = 0.86). Cardiac dysfunction and time of extracorporeal circulation showed a significant difference.
  
  
  CONCLUSIONS
  Data on respiratory system mechanics and oxygenation were not parameters for assessing the success or failure. Cardiac dysfunction and time of cardiopulmonary bypass, however, significantly interfered with the success in weaning patients from mechanical ventilation.
authors.affiliation: Instituto do Coração of the Hospital das Clínicas-FMUSP, Brazil.
authors.forename: Emília
authors.initials: E
authors.lastname: Nozawa
authors.forename: Eliane
authors.initials: E
authors.lastname: Kobayashi
authors.forename: Marta Erika
authors.initials: ME
authors.lastname: Matsumoto
authors.forename: Maria Ignêz
authors.initials: MI
authors.lastname: Feltrim
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Carmona
authors.forename: Júnior José Otávio Costa
authors.initials: JJ
authors.lastname: Auler
mesh_terms: D001938:Brazil / Q000453:epidemiology; D006348:Cardiac Surgical Procedures; D005112:Extracorporeal Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D012121:Respiration, Artificial; D012126:Respiratory Dead Space; D015656:Respiratory Mechanics; D013997:Time Factors; D014139:Tracheostomy; D016896:Treatment Outcome; D015300:Ventilator Weaning / Q000401:mortality / Q000592:standards