Objectives: Total hepatic venous blood flow is determined by the common hep
atic arterial blood flow and the venous outflow from stomach, spleen, pancr
eas, small intestine, and bowel, collected by the portal vein, and thus rep
resents overall splanchnic perfusion. We investigated whether transesophage
al echography (TEE) can provide a method for bedside assessment of hepatic
venous blood flow useful as a noninvasive method for measuring splanchnic p
erfusion in clinical practice.
Design and setting Experimental study in 15 anesthetized and ventilated pig
s in an animal research laboratory.
Interventions: TEE-derived calculations of hepatic venous blood flow were c
ompared with liver blood now measurements using perivascular ultrasound flo
w probes surgically positioned on portal vein and common hepatic artery. Pa
rameters were determined at baseline and after modulating splanchnic perfus
ion by either PEEP maneuver (15 cmH(2)O) or intravenous epinephrine (0.1 mu
g kg(-1) min(-1)).
Measurements and results: Diameter (d) and velocity time integral (VTI) of
ail three hepatic veins were determined by TEE, heart rate (HR) was derived
from electrocardiography and flow subsequently calculated as Q = pi (.) (d
/2)(2 .) 0.57 (.) VTI HR. Regression analysis of matched TEE and now probe
values showed a significant linear relationship (r(2) = 0.698). Bias analys
is revealed a systematic underestimation of liver blood flow by TEE, possib
ly due to use of 0.57 as correction factor for mean velocity, while changes
in liver blood now were reliably detected.
Conclusion: TEE offers a noninvasive approach for monitoring hepatic perfus
ion and may be used in patients.