Monitoreo de la volemia y el agua pulmonar extravascular en UCI / Monitoring of blood volume and the extravascular lung water in intensive care units

ABSTRACT

Traditionally Pulmonary wedge pressure (PWP) determination with Swan-Ganz catheter has been the gold standard to estimate ventricular preload in critically ill patients. However, the correlation between PWP and left ventricular telediastolic volume is poor, and the tecnique does not allow any estimation of extravascular lung water (EVLW). In the last years, several techniques have been developed to improve assessment of intra and extravascular volumes. Two tracers transcardiopulmonary dilution method was developed by Pearce et al in the early 60ïs. It used a thermal tracer to estimate intrathoracic total volumen (ITTV), and a colorimetric tracer for estimting intrathoracic blood volume (ITBV). The difference between ITTV and ITBV is called EVLW. Recently, the technique has been simplified to use just the thermal tracer. The Pulse Contour Cardiac Output computer (PiCCO, Pulsion Medizintechnik, Germany), allows a continous measurement of cardiac output and an intermittent measurement of ITTV, ITBV and EVLW. The use of this new technique could improve patient management, allowing optimal fluids administration without producing lung edema. Besides the PiCCO computer, both a standard central venous line in an upper body vein and a specially designed femoral artery line to measure thermal tracer dissipation are required. Preliminary experience has shown that it is a reliable method, with low morbidity and easy implementation, and may be a promising and useful tool in critical care patients