Is it feasible to monitor total hepatic blood flow by use of transesophageal echography? An experimental study in pigs.
OBJECTIVE
Total hepatic venous blood flow is determined by the common hepatic arterial blood flow and the venous outflow from stomach, spleen, pancreas, small intestine, and bowel, collected by the portal vein, and thus represents overall splanchnic perfusion. We investigated whether transesophageal echography (TEE) can provide a method for bedside assessment of hepatic venous blood flow useful as a noninvasive method for measuring splanchnic perfusion in clinical practice.


METHODS
Experimental study in 15 anesthetized and ventilated pigs in an animal research laboratory.


METHODS
TEE-derived calculations of hepatic venous blood flow were compared with liver blood flow measurements using perivascular ultrasound flow probes surgically positioned on portal vein and common hepatic artery. Parameters were determined at baseline and after modulating splanchnic perfusion by either PEEP maneuver (15 cmH2O) or intravenous epinephrine (0.1 microgram kg-1 min-1).


RESULTS
Diameter (d) and velocity time integral (VTI) of all 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 flow probe values showed a significant linear relationship (r2 = 0.698). Bias analysis revealed a systematic underestimation of liver blood flow by TEE, possibly due to use of 0.57 as correction factor for mean velocity, while changes in liver blood flow were reliably detected.


CONCLUSIONS
TEE offers a noninvasive approach for monitoring hepatic perfusion and may be used in patients.
Schütz
W
W
Universitätsklinik für Anästhesiologie, Universitätsklinikum Ulm, Steinhövelstrasse 9, 89075 Ulm, Germany. wolfram.schuetz@medizin.uni-ulm.de
Meierhenrich
R
R
Träger
K
K
Gauss
A
A
Radermacher
P
P
Georgieff
M
M
D000818:Animals; D015982:Bias; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D004195:Disease Models, Animal; D017548:Echocardiography, Transesophageal / Q000379:methods* / Q000592:standards; D004562:Electrocardiography; D004837:Epinephrine / Q000494:pharmacology; D005240:Feasibility Studies; D006499:Hepatic Artery / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D006503:Hepatic Veins / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D016014:Linear Models; D008099:Liver / Q000098:blood supply*; D008102:Liver Circulation / Q000187:drug effects / Q000502:physiology*; D008991:Monitoring, Physiologic / Q000379:methods* / Q000592:standards*; D019095:Point-of-Care Systems / Q000592:standards*; D011175:Positive-Pressure Respiration; D013552:Swine
D004837:Epinephrine