A. Aneman et al., Splanchnic circulation and regional sympathetic outflow, during peroperative PEEP ventilation in humans, BR J ANAEST, 82(6), 1999, pp. 838-842
Citations number
23
Categorie Soggetti
Aneshtesia & Intensive Care","Medical Research Diagnosis & Treatment
The splanchnic organs represent a major target for sympathetic outflow and
an important region for haemodynamic effects on cardiovascular homeostasis,
We have studied regional haemodynamic and sympathetic changes in the splan
chnic bed during standardized circulatory stress from positive end-expirato
ry pressure ventilation (PEEP). We investigated eight patients undergoing m
ajor upper abdominal surgery using a radiotracer method to measure plasma s
pillover of norepinephrine as an index of sympathetic nerve activity using
arterial, portal and hepatic venous blood sampling. Mesenteric and hepatic
perfusion were measured by ultrasound transit time flowmetry and blood-gas
analyses. Steady state measurements were performed before and during PEEP v
entilation at 10 cm H2O. Plasma spillover of norepinephrine in the mesenter
ic and hepatic organs represented mean 49 (SEM 8)% and 7 (2)% respectively,
of systemic norepinephrine spillover at baseline, and PEEP ventilation did
not cause any significant changes. However, PEEP ventilation significantly
decreased portal venous blood flow while hepatic blood flow was preserved
by a compensatory increase in hepatic arterial blood flaw. Mesenteric and h
epatic oxygen delivery changed according to blood flow, and there were no c
hanges in regional oxygen consumption. Thus PEEP ventilation altered mesent
eric and hepatic perfusion, independent of any change in corresponding symp
athetic nerve activity. Regulation of hepatic blood supply, not related to
sympathetic activity, maintained liver oxygenation during PEEP ventilation
despite a simultaneous decrease in mesenteric perfusion.