title: [Intrathoracic blood volume versus pulmonary artery occlusion pressure as estimators of cardiac preload in critically ill patients].
abstract: BACKGROUND
  Monitoring of cardiac preload by determination of pulmonary artery occlusion pressure (PAOP) has been traditionally used to guide fluid therapy to optimize cardiac output (CO). Since factors such as intrathoracic pressure and ventricular compliance may modify PAOP, volumetric estimators of preload have been developed. The PiCCO system is able to measure CO and intrathoracic blood volume (ITBV) by transpulmonary thermodilution.
  
  
  OBJECTIVE
  To compare a volumetric (ITBV) versus a pressure (PAOP) determination to accurately estimate cardiac preload in severely ill patients.
  
  
  METHODS
  From June 2001 to October 2003, 22 mechanically ventilated patients with hemodynamic instability underwent hemodynamic monitoring with pulmonary artery catheter (PAC) and PiCCO system. ITBV index (ITBVI), PAOP and CI were measured simultaneously by both methods. One hundred thirty eight deltas (D) were obtained from the difference of ITBVI, PAOP, CI-PAC and CI-PiCCO between 6-12 am and 6-12 pm. Linear regression analysis of DITBVI versus Eth CI-PiCCO and Eth PAOP versus DCI-PAC were made.
  
  
  RESULTS
  Mean age of patients was 60.8 +/- 19.4 years. APACHE II was 23.9 +/- 7. Fifteen patients met criteria for acute respiratory distress syndrome (ARDS). Delta ITBVI significantly correlated with DCI-PiCCO (r=0.54; 95% confidence interval = 0.41-0.65; p <0.01). There was no correlation between DPAOP and DCI-PAC.
  
  
  CONCLUSIONS
  ITBVI correlated better with CI than PAOP, and therefore it seems to be a more accurate estimator of preload in unstable, mechanically ventilated patients.
authors.affiliation: Departamento de Paciente Crítico, Facultad de Medicina, Clínica Alemana-Universidad del Desarrollo, Santiago, Chile. vinkotomicic@udd.cl
authors.forename: Vinko
authors.initials: V
authors.lastname: Tomicic
authors.forename: Jerónimo
authors.initials: J
authors.lastname: Graf
authors.forename: Ghislaine
authors.initials: G
authors.lastname: Echevarría
authors.forename: Mauricio
authors.initials: M
authors.lastname: Espinoza
authors.forename: Juan
authors.initials: J
authors.lastname: Abarca
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Montes
authors.forename: Javier
authors.initials: J
authors.lastname: Torres
authors.forename: Gastón
authors.initials: G
authors.lastname: Núñez
authors.forename: Julia
authors.initials: J
authors.lastname: Guerrero
authors.forename: Mario
authors.initials: M
authors.lastname: Luppi
authors.forename: Claudio
authors.initials: C
authors.lastname: Canals
mesh_terms: D000328:Adult; D001810:Blood Volume / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology*; D016638:Critical Illness; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D011446:Prospective Studies; D011669:Pulmonary Wedge Pressure / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology