title: Pulse pressure variation and volume responsiveness during acutely increased pulmonary artery pressure: an experimental study.
abstract: BACKGROUND
  We found that pulse pressure variation (PPV) did not predict volume responsiveness in patients with increased pulmonary artery pressure. This study tests the hypothesis that PPV does not predict fluid responsiveness during an endotoxin-induced acute increase in pulmonary artery pressure and right ventricular loading.
  
  
  METHODS
  Pigs were subjected to endotoxemia (0.4 microg/kg/hour lipopolysaccharide), followed by volume expansion, subsequent hemorrhage (20% of estimated blood volume), retransfusion, and additional stepwise volume loading until cardiac output did not increase further (n = 5). A separate control group (n = 7) was subjected to bleeding, retransfusion, and volume expansion without endotoxemia. Systemic hemodynamics were measured at baseline and after each intervention, and PPV was calculated offline. Prediction of fluid-challenge-induced stroke volume increase by PPV was analyzed using receiver operating characteristic (ROC) curves.
  
  
  RESULTS
  Sixty-eight volume challenges were performed in endotoxemic animals (22 before and 46 after hemorrhage), and 51 volume challenges in the controls. Endotoxin infusion resulted in an acute increase in pulmonary artery and central venous pressure and a decrease in stroke volume (all P < 0.05). In endotoxemia, 68% of volume challenges before hemorrhage increased the stroke volume by > 10%, but PPV did not predict fluid responsiveness (area under the ROC curve = 0.604, P = 0.461). After hemorrhage in endotoxemia, stroke volume increased in 48% and the predictive value of PPV improved (area under the ROC curve for PPV = 0.699, P = 0.021). In controls after hemorrhage, stroke volume increased in 67% of volume challenges and PPV was a predictor of fluid responsiveness (area under the ROC curve = 0.790, P = 0.001).
  
  
  CONCLUSIONS
  Fluid responsiveness cannot be predicted with PPV during acute pulmonary hypertension in porcine endotoxemia. Even following severe hemorrhage during endotoxemia, the predictive value of PPV is marginal.
authors.affiliation: Department of Intensive Care Medicine, University Hospital Inselspital and University of Bern, Freiburgstrasse, CH-3010 Bern, Switzerland. fritz.daudel@insel.ch
authors.forename: Fritz
authors.initials: F
authors.lastname: Daudel
authors.forename: David
authors.initials: D
authors.lastname: Tüller
authors.forename: Stefanie
authors.initials: S
authors.lastname: Krähenbühl
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Jakob
authors.forename: Jukka
authors.initials: J
authors.lastname: Takala
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D019446:Endotoxemia / Q000503:physiopathology; D005260:Female; D005440:Fluid Therapy; D006439:Hemodynamics / Q000502:physiology; D006973:Hypertension / Q000503:physiopathology*; D008070:Lipopolysaccharides; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D011651:Pulmonary Artery / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology*; D013552:Swine
chemical_list: D008070:Lipopolysaccharides