title: Ability of pulse contour and esophageal Doppler to estimate rapid changes in stroke volume.
abstract: OBJECTIVE
  Two technologies to acquire beat-to-beat stroke volume values exist, pulse contour analysis and esophageal Doppler monitoring. Pulse contour analysis assumes fixed aortic impedance. Esophageal Doppler assumes a constant proportional descending aortic flow and diameter. These assumptions may not be correct as arterial tone or myocardial contractility vary. We tested these relationships in the setting of rapidly changing stroke volumes and different cardiovascular states over a period of 10-15 cardiac cycles.
  
  
  METHODS
  In a university research facility we compared beat-to-beat changes in stroke volume as measure by aortic root flow probe or conductance catheter to pulse contour analysis and stroke distance as measured by esophageal Doppler.
  
  
  METHODS
  Five purpose-bred research hounds.
  
  
  METHODS
  To obtain a wide range of rapidly changing stroke volumes measurements were made during transient inferior vena cava occlusion. Data were gathered under baseline conditions and during norepinephrine, nitroprusside, and dobutamine infusions.
  
  
  RESULTS
  The pulse contour stroke volumes and esophageal Doppler stroke distance paralleled flow probe stroke volumes under all conditions (R(2)=0.89 for all measures). However, the absolute changes and proportional changes and the absolute values for both surrogate measures differed from absolute stroke volumes. Bland-Altman analysis showed no consistent bias or degree of precision across all animals under any given cardiovascular state.
  
  
  CONCLUSIONS
  Both pulse contour stroke volumes and esophageal Doppler derived stroke distance estimates yield significant correlations with aortic root flow probe. However, the absolute values, absolute changes, or proportional changes may not reflect actual stroke volumes as cardiovascular state varies, making their use in estimating absolute changes in stroke volume potentially inaccurate.
authors.affiliation: Medical Center, Department of Critical Care Medicine, University of Pittsburgh, 3550 Terrace Street, Pittsburgh, PA 15261, USA. gunnsr@ccm.upmc.edu
authors.forename: Scott R
authors.initials: SR
authors.lastname: Gunn
authors.forename: Hyung Kook
authors.initials: HK
authors.lastname: Kim
authors.forename: Peter W J
authors.initials: PW
authors.lastname: Harrigan
authors.forename: Michael R
authors.initials: MR
authors.lastname: Pinsky
mesh_terms: D000818:Animals; D001011:Aorta / Q000000981:diagnostic imaging* / Q000502:physiology; D006328:Cardiac Catheterization; D002302:Cardiac Output; D004280:Dobutamine / Q000494:pharmacology; D004285:Dogs; D015150:Echocardiography, Doppler; D017548:Echocardiography, Transesophageal; D008991:Monitoring, Physiologic; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011674:Pulse; D012044:Regression Analysis; D013318:Stroke Volume / Q000502:physiology*
chemical_list: D009599:Nitroprusside; D004280:Dobutamine; D009638:Norepinephrine