title: Radial artery pulse pressure variation correlates with brachial artery peak velocity variation in ventilated subjects when measured by internal medicine residents using hand-carried ultrasound devices.
abstract: BACKGROUND
  Rapid prediction of the effect of volume expansion is crucial in unstable patients receiving mechanical ventilation. Both radial artery pulse pressure variation (DeltaPP) and change of aortic blood flow peak velocity are accurate predictors but may be impractical point-of-care tools.
  
  
  OBJECTIVE
  We sought to determine whether respiratory changes in the brachial artery blood flow velocity (DeltaVpeak-BA) as measured by internal medicine residents using a hand-carried ultrasound (HCU) device could provide an accurate corollary to DeltaPP in patients receiving mechanical ventilation.
  
  
  METHODS
  Thirty patients passively receiving volume-control ventilation with preexisting radial artery catheters were enrolled. The brachial artery Doppler signal was recorded and analyzed by blinded internal medicine residents using a HCU device. Simultaneous radial artery pulse wave and central venous pressure recordings (when available) were analyzed by a blinded critical care physician.
  
  
  RESULTS
  A Doppler signal was obtained in all 30 subjects. The DeltaVpeak-BA correlated well with DeltaPP (r = 0.84) with excellent agreement (weighted kappa, 0.82) and limited intraobserver variability (2.8 +/- 2.8%) [mean +/- SD]. A DeltaVpeak-BA cutoff of 16% was highly predictive of DeltaPP > or = 13% (sensitivity, 91%; specificity, 95%). A poor correlation existed between the CVP and both DeltaVpeak-BA (r = - 0.21) and DeltaPP (r = - 0.16).
  
  
  CONCLUSIONS
  The HCU Doppler assessment of the DeltaVpeak-BA as performed by internal medicine residents is a rapid, noninvasive bedside correlate to DeltaPP, and a DeltaVpeak-BA cutoff of 16% may prove useful as a point-of-care tool for the prediction of volume responsiveness in patients receiving mechanical ventilation.
authors.affiliation: Division of Cardiovascular Diseases, Duke University Medical Center, 2300-2399 Erwin Road, Durham, NC 27710, USA. j.matthew.brennan.98@alum.dartmouth.org
authors.forename: J Matthew
authors.initials: JM
authors.lastname: Brennan
authors.forename: John E A
authors.initials: JE
authors.lastname: Blair
authors.forename: Chetan
authors.initials: C
authors.lastname: Hampole
authors.forename: Sascha
authors.initials: S
authors.lastname: Goonewardena
authors.forename: Samip
authors.initials: S
authors.lastname: Vasaiwala
authors.forename: Dipak
authors.initials: D
authors.lastname: Shah
authors.forename: Kirk T
authors.initials: KT
authors.lastname: Spencer
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Schmidt
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001916:Brachial Artery / Q000000981:diagnostic imaging* / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D005260:Female; D006801:Humans; D007396:Internship and Residency; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D019095:Point-of-Care Systems / Q000706:statistics & numerical data*; D011175:Positive-Pressure Respiration; D017534:Radial Artery / Q000000981:diagnostic imaging* / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D012121:Respiration, Artificial / Q000009:adverse effects; D015656:Respiratory Mechanics; D013318:Stroke Volume / Q000502:physiology*; D018608:Ultrasonography, Doppler / Q000295:instrumentation; D016277:Ventricular Function, Left / Q000502:physiology