Aeh. El-desoky et al., Measurement of hepatic tissue hypoxia using near infrared spectroscopy: Comparison with hepatic vein oxygen partial pressure, EUR SURG RE, 32(4), 2000, pp. 207-214
Hepatic hypoxia occurs during liver surgery and transplantation. The critic
al level associated with irreversible hepatocellular damage is unknown. Mea
surement of hepatic tissue oxygenation and hepatic vein oxygen partial pres
sure (HVPO2) reflects oxygen supply and consumption. Near infrared spectros
copy (NIRS) can be used to monitor hepatic oxyhaemoglobin (HbO(2)), deoxyha
emoglobin (Hb) and cytochrome oxidase (Cyt Ox) oxidation. This study compar
ed regional hepatic tissue oxygenation (HbO2, Hb and Cyt Ox) using NIRS wit
h HVPO2. The use of tissue oxygenation measured by NIRS and HVPO2 as indica
tors of hepatic tissue hypoxia was also investigated. Large Landrace pigs (
n = 5) underwent laparotomy and liver exposure. Systemic and hepatic haemod
ynamics were monitored continuously. NIRS probes were placed on the liver t
o record continuously HbO(2), Hb and Cyt Ox. Graded hypoxaemia was achieved
by stepwise reduction of the fraction of inspired oxygen (FiO(2)) from 30%
(baseline) to 4%, A significant decrease in hepatic arterial blood flow an
d total hepatic blood flow was seen with severe hypoxaemia while there was
no significant change to portal vein blood flow. Oxygen partial pressures i
n the hepatic artery, portal vein and hepatic vein decreased progressively
with all grades of hypoxaemia. There was an immediate reduction of hepatic
HbO(2) and simultaneous increase in hepatic Hb with all grades of hypoxaemi
a. Hepatic Cyt Ox was reduced significantly only with FiO(2) less than or e
qual to 10%. A significant correlation (p < 0.001) was found between the ch
anges in hepatic oxygenation parameters measured by NIRS and HVPO2. HVPO2 m
easurement did not predict the reduction in intracellular tissue oxygenatio
n demonstrated by NIRS with a decrease of Cyt Ox oxidation. In conclusion t
here was a good correlation between the tissue oxygenation parameters measu
red by NIRS and HVPO2. However, the reduction of intracellular oxygenation
found with severe hypoxaemia was demonstrated only by NIRS. Copyright (C) 2
000 S. Karger AG, Basel.