title: Noninvasive optimization of left ventricular filling using esophageal Doppler.
abstract: OBJECTIVE
  To confirm whether the descending aortic blood flow velocity waveform variable of flow time corrected for heart rate, measured using an esophageal Doppler transducer, can be used for noninvasive optimization of left ventricular (LV) filling.
  
  
  METHODS
  ICU and operating theater.
  
  
  METHODS
  Forty-three mechanistically ventilated patients in the ICU or undergoing cardiothoracic surgery in whom a pulmonary arterial catheter was in situ.
  
  
  METHODS
  LV preload was a) increased from hypovolemic states (pulmonary arterial occlusion pressure [PAOP] less than 8 mm Hg) by fluid challenge, b) decreased from normovolemic states (PAOP 10 to 15 mm Hg) by either iv nitrates or intravascular fluid loss, and c) decreased from heart failure or fluid overload states (PAOP greater than 20 mm Hg) by iv nitrates. No other maneuver was performed concurrently.
  
  
  RESULTS
  Descending aortic blood flow was measured by an esophageal Doppler transducer. Corrected flow time was calculated by dividing systolic flow time by the square root of the cycle time. PAOP and corrected flow time increased after fluid challenges in hypovolemic states, and decreased when LV preload was decreased from normovolemic states. However, when preload was decreased from overload states, PAOP always decreased, but the corrected flow time usually increased before any subsequent decrease. The greatest value of corrected flow time corresponded with the maximal stroke volume seen.
  
  
  CONCLUSIONS
  Esophageal Doppler measurement of aortic blood flow can be used for rapid, noninvasive optimization of LV filling in mechanically ventilated patients.
authors.affiliation: Department of Medicine, St. George's Hospital Medical School, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Singer
authors.forename: E D
authors.initials: ED
authors.lastname: Bennett
mesh_terms: D001011:Aorta / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D015150:Echocardiography, Doppler / Q000295:instrumentation / Q000379:methods*; D004947:Esophagus; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D011669:Pulmonary Wedge Pressure / Q000502:physiology; D013815:Thermodilution; D013997:Time Factors; D014159:Transducers; D016277:Ventricular Function, Left / Q000502:physiology*