title: Noninvasive cardiac output measurement in heart failure subjects on circulatory support.
abstract: BACKGROUND
  Pulmonary artery catheter (PAC) thermodilution is commonly used in the perioperative cardiac surgical intensive care unit for measurement and management of central hemodynamics despite questions about effectiveness, difficulty of use, and safety. USCOM is a noninvasive continuous wave Doppler device for direct measurement of cardiac output (CO) and is an alternative to PAC. USCOM validation has predominantly been in the cardiac surgical intensive care unit against PAC, despite the recognized limitations in reliability of the method. We compared USCOM CO measurements with the CardioWest, an orthotopic total artificial heart (TAH), in heart failure (HF) subjects during controlled interventions.
  
  
  METHODS
  CO, stroke volume (SV), and heart rate (HR) were measured in a blinded fashion using the CardioWest and the USCOM device in TAH HF patients. Five-hundred eight paired measures from 18 examinations of seven subjects were acquired as flow was varied by the CardioWest controller. Bland-Altman analysis was used to compare agreement.
  
  
  RESULTS
  Mean values and standard deviations (+/-SD) for CO, SV, and HR by CardioWest and USCOM were 7.33 +/- 0.46 and 7.34 +/- 0.51 L/min, 56.2 +/- 3.8 and 56.6 +/- 3.8 mL, and 131 +/- 3 and 130 +/- 4 bpm, respectively. CO ranged from 5.2 to 9.3 L/min. The mean differences between methods for CO, SV, and HR were -0.01 +/- 0.23 L/min, -0.34 +/- 1.97 mL, and 0.9 +/- 2.3 bpm, respectively, with mean percentage differences of -0.3%, -0.6%, and 0.7%. The percentage limits of agreement for CO, SV, and HR were 6.4%, 7.1%, and 3.6%.
  
  
  CONCLUSIONS
  USCOM is a feasible and accurate method for noninvasive measurement and monitoring of CO in TAH HF patients and may have a wider application in diagnosis and management of cardiovascular disease.
authors.affiliation: Department of Medicine, The University of Queensland, Brisbane, Australia. rap.echo@bigpond.com
authors.forename: Rob
authors.initials: R
authors.lastname: Phillips
authors.forename: Peter
authors.initials: P
authors.lastname: Lichtenthal
authors.forename: Julie
authors.initials: J
authors.lastname: Sloniger
authors.forename: Darryl
authors.initials: D
authors.lastname: Burstow
authors.forename: Malcolm
authors.initials: M
authors.lastname: West
authors.forename: Jack
authors.initials: J
authors.lastname: Copeland
mesh_terms: D000465:Algorithms; D002302:Cardiac Output / Q000502:physiology*; D016887:Cardiopulmonary Resuscitation; D017097:Electric Impedance; D004947:Esophagus / Q000000981:diagnostic imaging; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D007201:Indicator Dilution Techniques; D008168:Lung / Q000502:physiology; D016343:Monitoring, Intraoperative / Q000379:methods*; D013815:Thermodilution; D018608:Ultrasonography, Doppler