title: Unilateral postoperative pulmonary edema after minimally invasive cardiac surgical procedures: a case-control study.
abstract: BACKGROUND
  Unilateral postoperative pulmonary edema is an underreported adverse event after a minimally invasive cardiac surgical procedure that combines right minithoracotomy with cardiopulmonary bypass. We sought to characterize its incidence, risk factors, and morbidity.
  
  
  METHODS
  We conducted a retrospective case-control study of all cardiac surgical procedures that combined right-sided minithoracotomy with cardiopulmonary bypass at our institution over 8 consecutive years. Unilateral postoperative pulmonary edema was defined on the chest radiograph taken on the first postoperative day as relatively increased opacification of the right versus left hemithorax involving at least 20% of the hemithorax, not better explained by atelectasis. Baseline characteristics, potential risk factors, and outcomes were subject to univariable and multivariable analysis.
  
  
  RESULTS
  Radiographs were available for 277 of 278 patients; of those, 68 (25%) met our definition of unilateral postoperative pulmonary edema. Patients with unilateral postoperative pulmonary edema had higher mortality and were more likely to have a lower postoperative PaO2/FIO2 ratio, to require vasoactive medications and mechanical ventilation for longer than 24 hours, and to have longer lengths of stay in the intensive care unit and the hospital. Unilateral postoperative pulmonary edema was independently associated with chronic obstructive pulmonary disease (odds ratio [OR] 4.79; 95% confidence interval [CI] 1.28 to 18.0; p = 0.02); pulmonary hypertension, right-ventricular dysfunction, or both (OR 2.92; 95% CI 1.41 to 6.03; p = 0.004); and increasing cardiopulmonary bypass time (OR 1.019; 95% CI 1.011 to 1.027 per additional minute; p <0.001).
  
  
  CONCLUSIONS
  Unilateral postoperative pulmonary edema after minimally invasive cardiac surgical procedures is common, carries significant morbidity, and has identifiable risk factors. Further research is needed to enable a better understanding of the pathophysiology and clinical implications of unilateral postoperative pulmonary edema.
authors.affiliation: Program in Critical Care, Department of Medicine, London Health Sciences Centre, Victoria Hospital, London, Ontario, Canada.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Tutschka
authors.affiliation: Program in Critical Care, Department of Medicine, London Health Sciences Centre, Victoria Hospital, London, Ontario, Canada; Department of Anesthesia & Perioperative Medicine, London Health Sciences Centre, University Hospital, London, Ontario, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bainbridge
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, London Health Sciences Centre, University Hospital, London, Ontario, Canada.
authors.forename: Michael W A
authors.initials: MW
authors.lastname: Chu
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, London Health Sciences Centre, University Hospital, London, Ontario, Canada.
authors.forename: Bob
authors.initials: B
authors.lastname: Kiaii
authors.affiliation: Program in Critical Care, Department of Medicine, London Health Sciences Centre, Victoria Hospital, London, Ontario, Canada; Department of Anesthesia & Perioperative Medicine, London Health Sciences Centre, University Hospital, London, Ontario, Canada; Department of Epidemiology & Biostatistics, Western University, London, Ontario, Canada. Electronic address: philip.jones@lhsc.on.ca.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Jones
mesh_terms: D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects*; D011654:Pulmonary Edema / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013908:Thoracotomy / Q000009:adverse effects*