title: Hemodynamic Effect of Different Doses of Fluids for a Fluid Challenge: A Quasi-Randomized Controlled Study.
abstract: OBJECTIVE
  The objectives of this study are to determine what is the minimal volume required to perform an effective fluid challenge and to investigate how different doses of IV fluids in an fluid challenge affect the changes in cardiac output and the proportion of responders and nonresponders.
  
  
  METHODS
  Quasi-randomized controlled trial.
  
  
  METHODS
  Cardiothoracic ICU, tertiary university hospital.
  
  
  METHODS
  Eighty postcardiac surgery patients.
  
  
  METHODS
  IV infusion of 1, 2, 3, or 4 mL/Kg (body weight) of crystalloid over 5 minutes.
  
  
  RESULTS
  Mean systemic filling pressure measured using the transient stop-flow arm arterial-venous equilibrium pressure, arterial and central venous pressure, cardiac output (LiDCOplus; LiDCO, Cambridge, United Kingdom), and heart rate. The groups were well matched with respect to demographic and baseline physiologic variables. The proportion of responders increased from 20% in the group of 1 mL/kg to 65% in the group of 4 mL/kg (p = 0.04). The predicted minimal volume required for an fluid challenge was between 321 and 509 mL. Only 4 mL/Kg increases transient stop-flow arm arterial-venous equilibrium pressure beyond the limits of precision and was significantly associated with a positive response (odds ratio, 7.73; 95% CI, 1.78-31.04).
  
  
  CONCLUSIONS
  The doses of fluids used for an fluid challenge modify the proportions of responders in postoperative patients. A dose of 4 mL/Kg increases transient stop-flow arm arterial-venous equilibrium pressure and reliably detects responders and nonresponders.
authors.affiliation: 1Adult Critical Care Directorate, St George's University Hospitals NHS Foundation Trust and St George's University of London, London, United Kingdom. 2Institute of Infection and Immunity, St George's University of London, London, United Kingdom.
authors.forename: Hollmann D
authors.initials: HD
authors.lastname: Aya
authors.forename: Andrew
authors.initials: A
authors.lastname: Rhodes
authors.forename: Irina
authors.initials: I
authors.lastname: Chis Ster
authors.forename: Nick
authors.initials: N
authors.lastname: Fletcher
authors.forename: R Michael
authors.initials: RM
authors.lastname: Grounds
authors.forename: Maurizio
authors.initials: M
authors.lastname: Cecconi
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D000077324:Crystalloid Solutions; D004305:Dose-Response Relationship, Drug; D005260:Female; D005440:Fluid Therapy / Q000379:methods*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007262:Infusions, Intravenous; D007552:Isotonic Solutions / Q000008:administration & dosage* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015532:Rehydration Solutions / Q000008:administration & dosage* / Q000627:therapeutic use; D016037:Single-Blind Method
chemical_list: D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D015532:Rehydration Solutions