title: Prolonged postoperative respiratory support after proximal thoracic aortic surgery: Is deep hypothermic circulatory arrest a risk factor?
abstract: OBJECTIVE
  In addition to the pulmonary risks associated with cardiopulmonary bypass, thoracic aortic surgery using deep hypothermic circulatory arrest (DHCA) may subject the lungs to further injury. However, this topic has received little investigation to date.
  
  
  METHODS
  A prospective cohort review was performed on all patients undergoing proximal thoracic aortic surgery with (n = 478) and without (n = 135) DHCA between July 2005 and February 2013 at a single institution. The primary outcome was prolonged postoperative respiratory support (PPRS), defined as any of the following: >1 day of mechanical ventilation at either fraction of inspired oxygen >0.4 and/or positive end-expiratory pressure >5 mm Hg, >2 days of supplemental O2 requirement of at least 2.5 L/min, or discharge with new O2 requirement. Independent risk factors for PPRS were identified using multivariable logistic regression.
  
  
  RESULTS
  Postoperative respiratory support was required in 100 patients (20.9%) with and 30 patients (22.2%) without DHCA (P = .74). Independent predictors of PPRS after proximal aortic surgery included the following: age, diabetes, history of stroke, preoperative creatinine, American Society of Anesthesiologists class 4, redo-sternotomy, total arch replacement, and transfusion requirement. Use of DHCA was not an independent risk factor for PPRS in the entire cohort. Subanalysis of only DHCA patients revealed that longer DHCA times were independently associated with PPRS.
  
  
  CONCLUSIONS
  Prolonged postoperative respiratory support is common after proximal aortic surgery. The use of DHCA was not associated with this complication in the overall cohort, although longer DHCA times were predictive when only the subset of patients undergoing DHCA was analyzed. Knowledge of the risk factors for PPRS after proximal aortic surgery should improve preoperative risk stratification and postoperative management of these patients.
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Schechter
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Asad A
authors.initials: AA
authors.lastname: Shah
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Englum
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Judson B
authors.initials: JB
authors.lastname: Williams
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Asvin M
authors.initials: AM
authors.lastname: Ganapathi
authors.affiliation: Department of Respiratory Services, Duke University Medical Center, Durham, NC.
authors.forename: John D
authors.initials: JD
authors.lastname: Davies
authors.affiliation: Department of Anesthesia, Duke University Medical Center, Durham, NC.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Welsby
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC. Electronic address: gchad.hughes@duke.edu.
authors.forename: G Chad
authors.initials: GC
authors.lastname: Hughes
mesh_terms: D000328:Adult; D000368:Aged; D001013:Aorta, Thoracic / Q000601:surgery*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D050792:Circulatory Arrest, Deep Hypothermia Induced / Q000009:adverse effects*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy / Q000706:statistics & numerical data; D011184:Postoperative Period; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors
keywords: Aorta; Circulatory arrest; Deep hypothermia induced; Respiration; Risk factors; Thoracic surgical procedures