title: Pulse wave transit time measurements of cardiac output in patients undergoing partial hepatectomy: a comparison of the esCCO system with thermodilution.
abstract: BACKGROUND
  Measuring cardiac output accurately during anesthesia is thought to be helpful for safely controlling hemodynamics. Several minimally invasive methods to measure cardiac output have been developed as alternatives to thermodilution with pulmonary artery catheterization. We evaluated the reliability of a novel pulse wave transit time method of cardiac output assessment to trend with thermodilution cardiac output in patients undergoing partial hepatectomy.
  
  
  METHODS
  Thirty-one patients (ASA physical status II or III) undergoing partial hepatectomy under general anesthesia were evaluated. Cardiac output measurements by pulse wave transit time method and by thermodilution were recorded after induction of anesthesia, after a change in body positioning to 20° head up, after a change to 20° head down, after volume challenge with 10 mL·kg hydroxyethyl starch 6%, during the Pringle maneuver, and immediately after Pringle maneuver release. Trending was assessed using Bland-Altman analysis and concordance analysis.
  
  
  RESULTS
  The direction of change between consecutive pulse wave transit time measurements and the corresponding thermodilution measurements showed a concordance rate of 96.0% (lower 95% confidence interval = 64%), with limits of agreement -1.51 and 1.61 L·min.
  
  
  CONCLUSIONS
  The pulse wave transit time method had good concordance but fairly wide limits of agreement with regard to trending in patients with changes in preload and systemic vascular resistance. There are potential inaccuracies when vasopressors are used to treat hypotension associated with decreased systemic vascular resistance. The study limitations are that the cardiac output data were collected in a nonblinded fashion, and an existing intraarterial catheter was used, although the system requires only routine, noninvasive cardiovascular monitors. This is a promising technique that currently has limitations and will require further improvements and clinical assessment.
authors.affiliation: From the *Department of Anesthesiology, National Defense Medical College, Saitama †Vital Sign Sensor Department, Monitoring Technology Center, Nihon Kohden Corporation, Tokyo, Japan; and ‡Department of Anesthesiology, University California, San Diego Medical Center, San Diego, California.
authors.forename: Masato
authors.initials: M
authors.lastname: Tsutsui
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Araki
authors.forename: Kenichi
authors.initials: K
authors.lastname: Masui
authors.forename: Tomiei
authors.initials: T
authors.lastname: Kazama
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sugo
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Archer
authors.forename: Gerard R
authors.initials: GR
authors.lastname: Manecke
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D062186:Arterial Pressure; D002302:Cardiac Output; D005260:Female; D006339:Heart Rate; D006498:Hepatectomy / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D056888:Patient Positioning; D011237:Predictive Value of Tests; D063177:Pulse Wave Analysis / Q000295:instrumentation; D015203:Reproducibility of Results; D013815:Thermodilution; D013997:Time Factors; D014655:Vascular Resistance