title: Agreement of cardiac output measurement between pulse contour analysis and thermodilution in various body positions: a porcine study.
abstract: BACKGROUND
  We elucidated the effects of various body positions on the agreement of cardiac output (CO) measurement between pulse contour analysis with the PiCCO monitor and thermodilution with pulmonary artery catheterization.
  
  
  METHODS
  Fifteen anesthetized and mechanically ventilated pigs (40 ± 2 kg) were sequentially placed in various positions to facilitate simultaneous CO measurement. Between-methods agreement was assessed using the Bland-Altman method. Trending ability was assessed using Pearson product-moment correlation coefficient analysis.
  
  
  RESULTS
  In supine, reverse Trendelenburg, Trendelenburg, and left lateral decubitus (lateral) positions, CO measured by these two methods was comparable (4.9 ± 1.5 versus 4.6 ± 1.6 L/min, 4.6 ± 2.2 versus 4.8 ± 1.8 L/min, 5.1 ± 2.1 versus 4.9 ± 2.1 L/min, and 5.4 ± 1.8 versus 5.0 ± 1.6 L/min; all P > 0.05). Mean bias between methods and limits of agreement (percentage error) were 0.3 ± 2.9 L/min (61%), -0.3 ± 3.3 L/min (71%), 0.1 ± 4.1 L/min (77%), and 0.5 ± 3.7 L/min (71%). Directional changes of paired CO revealed 66% (reverse Trendelenburg), 57% (Trendelenburg), and 66% (lateral) concordance. The correlation coefficient (r(2)) was 0.199, 0.127, and 0.108. For paired CO ≤6 L/min, mean bias between methods and limits of agreement (percentage error) were 0.2 ± 1.0 L/min (25%), -0.1 ± 1.0 L/min (28%), 0.2 ± 1.1 L/min (29%), and 0.5 ± 0.9 L/min (23%). Directional changes of paired CO revealed 84% (reverse Trendelenburg), 76% (Trendelenburg), and 65% (lateral) concordance. The correlation coefficient (r2) was 0.583, 0.626, and 0.213.
  
  
  CONCLUSIONS
  The mean CO measured by pulse contour analysis and thermodilution did not agree well in various body positions. Moreover, the measurements tended to trend differently in response to positional changes. For paired CO ≤6 L/min, however, the between-methods agreement and the trending ability improved significantly.
authors.affiliation: Department of Anesthesiology, Buddhist Tzu Chi General Hospital, Taipei Branch, Taipei, Taiwan.
authors.forename: Ping-Cheng
authors.initials: PC
authors.lastname: Shih
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Hung
authors.forename: Ying-Lun
authors.initials: YL
authors.lastname: Chen
authors.forename: Hsin-Jung
authors.initials: HJ
authors.lastname: Tsai
authors.forename: Chia-Ying
authors.initials: CY
authors.lastname: Chen
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Huang
mesh_terms: D000818:Animals; D002302:Cardiac Output; D002406:Catheterization, Peripheral; D005260:Female; D016014:Linear Models; D056888:Patient Positioning / Q000379:methods*; D011651:Pulmonary Artery; D011674:Pulse; D015203:Reproducibility of Results; D013552:Swine; D013815:Thermodilution