Ms. Dahn et al., The influence of hepatic venous oxygen saturation on the liver's syntheticresponse to metabolic stress, P SOC EXP M, 221(1), 1999, pp. 39-45
Citations number
34
Categorie Soggetti
Medical Research General Topics
Journal title
PROCEEDINGS OF THE SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE
Hepatic oxygen consumption (HVO2) and hepatic venous oxygen saturation (Shv
O2) were assessed in the isolated perfused rat liver under conditions that
mimic critical illness in an effort to assess their utility in predicting t
he functional status of the liver. Flow rates were adjusted over the physio
logic range of oxygen transport as indicated by the hepatic venous O-2 satu
ration range of 10%-75%. HVO2, was found to be transport (HDO2) dependent o
nly when perfusate conditions contained an increased counterregulatory horm
one (glucagon, epinephrine, dexamethasone) stimulus or a high lactate conce
ntration. In the absence of a metabolic load, (substrate and hormone-free p
erfusate), HVO2 was transport independent even at an ShvO2 as low as 10%, A
lthough transport dependency of HVO2 is frequently used to infer tissue isc
hemia, hepatic oxygen consumption was poorly correlated with synthetic func
tion under all conditions. In contrast, hepatic albumin production was dire
ctly related to ShvO2 at all levels of HDO2 and under all perfusion conditi
ons indicating that this metabolic process is particularly sensitive to red
uctions in oxygen availability, which is more reliably predicted by venous
saturation measurements. However, glucose and urea synthesis were almost in
dependent of ShvO2. These findings indicate that various hepatic processes
are affected differentially by stress conditions and flow alterations that
may exist during critical illness, and protein synthesis is particularly se
nsitive to oxygen deprivation. Additionally, hepatic venous oxygen saturati
on measurement, but not HVO2 serves as a useful surrogate marker for hepati
c albumin production suggesting that regional venous oximetry may play an i
mportant role in the detection of hepatic functional impairment.