title: Use of pulse pressure variation to estimate changes in preload during experimental acute normovolemic hemodilution.
abstract: BACKGROUND
  Acute normovolemic hemodilution (ANH) is an alternative to blood transfusion in surgeries involving blood loss. This experimental study was designed to evaluate whether pulse pressure variation (PPV) would be an adequate tool for monitoring changes in preload during ANH, as assessed by transesophageal echocardiography.
  
  
  METHODS
  Twenty-one anesthetized and mechanically ventilated pigs were randomized into three groups: CTL (control), HES (hemodilution with 6% hydroxyethyl starch at a 1:1 ratio) or NS (hemodilution with saline 0.9% at a 3:1 ratio). Hemodilution was performed in animals of groups NS and HES in two stages, with target hematocrits 22% and 15%, achieved at 30-minute intervals. After two hours, 50% of the blood volume withdrawn was transfused and animals were monitored for another hour. Statistical analysis was based on ANOVA for repeated measures followed by multiple comparison test (P<0.05). Pearson's correlations were performed between changes in left ventricular end-diastolic volume (LVEDV) and PPV, central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP).
  
  
  RESULTS
  Group NS received a significantly greater amount of fluids during ANH (NS, 900 ± 168 mL vs. HES, 200 ± 50 mL, P<0.05) and presented greater urine output (NS, 2643 ± 1097 mL vs. HES, 641 ± 338 mL, P<0.001). Significant decreases in LVEDV were observed in group NS from completion of ANH until transfusion. In group HES, only increases in LVEDV were observed, at the end of ANH and at transfusion. Such changes in LVEDV (∆LVEDV) were better reflected by changes in PPV (∆PPV, R=-0.62) than changes in CVP (∆CVP, R=0.32) or in PAOP (∆PAOP, R=0.42, respectively).
  
  
  CONCLUSIONS
  Changes in preload during ANH were detected by changes in PPV. ∆PPV was superior to ∆PAOP and ∆CVP to this end.
authors.affiliation: Postgraduate Anesthesiology Program, Faculdade de Medicina da Universidade de São Paulo, Brazil.
authors.forename: A J
authors.initials: AJ
authors.lastname: Sant'Ana
authors.forename: D A
authors.initials: DA
authors.lastname: Otsuki
authors.forename: J
authors.initials: J
authors.lastname: Noel-Morgan
authors.forename: V F
authors.initials: VF
authors.lastname: Leite
authors.forename: D T
authors.initials: DT
authors.lastname: Fantoni
authors.forename: L
authors.initials: L
authors.lastname: Abrahao Hajjar
authors.forename: F R
authors.initials: FR
authors.lastname: Barbosa Gomes Galas
authors.forename: J
authors.initials: J
authors.lastname: Pinheiro De Almeida
authors.forename: J
authors.initials: J
authors.lastname: Fukushima
authors.forename: J O
authors.initials: JO
authors.lastname: Costa Auler
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D001810:Blood Volume / Q000502:physiology*; D001830:Body Surface Area; D001835:Body Weight / Q000502:physiology; D002496:Central Venous Pressure / Q000502:physiology; D003102:Colloids / Q000627:therapeutic use; D000077324:Crystalloid Solutions; D017548:Echocardiography, Transesophageal; D006321:Heart / Q000502:physiology; D006438:Hemodilution / Q000379:methods*; D006439:Hemodynamics / Q000502:physiology; D007552:Isotonic Solutions / Q000627:therapeutic use; D010952:Plasma Substitutes / Q000627:therapeutic use; D011651:Pulmonary Artery / Q000502:physiology; D013552:Swine
chemical_list: D003102:Colloids; D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D010952:Plasma Substitutes