[Intrathoracic blood volume versus pulmonary artery occlusion pressure as estimators of cardiac preload in critically ill patients].
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.
Tomicic
Vinko
V
Departamento de Paciente Crítico, Facultad de Medicina, Clínica Alemana-Universidad del Desarrollo, Santiago, Chile. vinkotomicic@udd.cl
Graf
Jerónimo
J
Echevarría
Ghislaine
G
Espinoza
Mauricio
M
Abarca
Juan
J
Montes
José Miguel
JM
Torres
Javier
J
Núñez
Gastón
G
Guerrero
Julia
J
Luppi
Mario
M
Canals
Claudio
C
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