title: Risk factors of prolonged mechanical ventilation following open heart surgery: what has changed over the last decade?
abstract: OBJECTIVE
  To identify the risk factors for prolonged invasive mechanical ventilation after open heart surgery in Pakistan.
  
  
  METHODS
  This study is based on retrospective analysis of database.
  
  
  METHODS
  We conducted study of all patients who underwent open heart surgery at CPE Institute of Cardiology, Multan from March 2009 to May 2011.
  
  
  METHODS
  The data was retrieved from the database in the form of electronic spreadsheet which was then analyzed using SPSS software. The patients with incomplete data entries were removed from the analysis resulting in a set of 1,617 patients. The data of each patient consisted of 65 preoperative, operative and postoperative variables. The data was summarized as means, medians and standard deviations for numeric variables and frequencies and percentages or categoric variables. These risk factors were compared using Chi-sqaure test. Their ODDs ratios and 95% confidence intervals of ODD's Ratios and P values were calculated.
  
  
  RESULTS
  Out of a total of 1,617 patients, 77 patients (4.76%) had prolonged ventilation for a cumulated duration of more than over 24 hours. Preoperative renal failure, emphysema, low EF (<30%), urgent operation, preoperative critical state, prolonged bypass time, prolonged cross clamp time, complex surgical procedures and peri-operative myocardial infarction were found to be risk factors for PIMV. Old age, female gender, advanced ASA class, advanced NYHA class, diabetes mellitus, smoking, history of COPD, redo surgery, left main stenosis, obesity and use of intra-aortic balloon pump were not found to have significant ODDs ratios for PIMV. The patients with prolonged ventilation had significantly high mortality i.e. 32.47% while the normal ventilation group had 0.32% overall mortality.
  
  
  CONCLUSIONS
  Many of the previously considered risk factors for prolonged ventilation after open heart study are no more significant risk factors. However, prolonged ventilation continues to be associated with very high mortality.
authors.affiliation: Senior Registrar, Department of Cardiac Surgery, CPE Institute of Cardiology, Abdali Road, Multan, Pakistan;
authors.forename: Muhammad-Mujtaba Ali
authors.initials: MM
authors.lastname: Siddiqui
authors.forename: Iftikhar
authors.initials: I
authors.lastname: Paras
authors.forename: Anjum
authors.initials: A
authors.lastname: Jalal
keywords: Extracorporeal circulation induced lung injury; open heart surgery; prolonged ventilation; respiratory failure