title: Effect of prone positioning systems on hemodynamic and cardiac function during lumbar spine surgery: an echocardiographic study.
abstract: METHODS
  Prospective randomized study of patients undergoing spine surgery.
  
  
  OBJECTIVE
  To compare changes in hemodynamic and cardiac function after prone positioning using different prone positioners.
  
  
  BACKGROUND
  Prone positioning decreases blood pressure and cardiac function. Several studies have evaluated changes in cardiac function after prone positioning, and linked them to reduced venous return and ventricular compliance. This study compares different prone positioners using transesophageal echocardiography, and determines their effect on cardiac function and hemodynamics.
  
  
  METHODS
  After correction of fluid deficits with the patient under stable anesthesia, hemodynamic and cardiac performance was measured using transesophageal echocardiography. After prone positioning, repeat measurements were performed, and comparisons were made between prone and supine positions.
  
  
  RESULTS
  No intergroup differences in demographics, fluid deficit, baseline hemodynamics, or differences from supine to prone position were noted. Cardiac output decreased with the Wilson (Union City, CA) and Siemens AG (Munich, Germany) frames, while cardiac index and stroke volume decreased with the Andrews (Hollywood, CA), Wilson, and Siemens systems. Cardiac preload decreased using the Andrews frame. The Jackson spine table (Hollywood, CA) and bolsters had the least effect on cardiac performance.
  
  
  CONCLUSIONS
  Adequate fluid replacement reduced hypotension and hemodynamic instability after prone positioning. The Jackson spine table and longitudinal bolsters had minimal effects on cardiac function, and should be considered in patients with limited cardiac reserve.
authors.affiliation: Department of Anesthesiology, Loyola University Medical Center, Maywood, IL 60153, USA.
authors.forename: Sreenivasa
authors.initials: S
authors.lastname: Dharmavaram
authors.forename: W Scott
authors.initials: WS
authors.lastname: Jellish
authors.forename: Russ P
authors.initials: RP
authors.lastname: Nockels
authors.forename: John
authors.initials: J
authors.lastname: Shea
authors.forename: Rashid
authors.initials: R
authors.lastname: Mehmood
authors.forename: Alex
authors.initials: A
authors.lastname: Ghanayem
authors.forename: Bruce
authors.initials: B
authors.lastname: Kleinman
authors.forename: William
authors.initials: W
authors.lastname: Jacobs
mesh_terms: D000328:Adult; D001794:Blood Pressure; D002302:Cardiac Output; D017548:Echocardiography, Transesophageal; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D016684:Prone Position; D013318:Stroke Volume; D016683:Supine Position