Increased spillover of norepinephrine to the portal vein during CO-pneumoperitoneum in pigs.
BACKGROUND
Elevated intra abdominal pressure (IAP) during CO2-insufflation has been associated with increased catecholamine concentrations in plasma. We have previously indicated that this may be due to a regional increased spillover from the abdominal region. In this experimental study we investigated catecholamine spillover from the drainage area of the portal vein during CO2-pneumoperitoneum.


METHODS
Eight pigs under general anesthesia were investigated before and after CO2-pneumoperitoneum with an IAP of 15 mmHg. Regional spillover of catecholamines was determined by measuring plasma catecholamine concentrations and flow simultaneously. Plasma concentrations of catecholamines were measured from the portal and femoral veins, the pulmonary and carotid arteries. Flow data were collected with laser-Doppler transit time flow probes around the portal and femoral veins. Cardiac output was measured by the thermo-dilution technique. Estimated spillover was calculated by the veno-arterial difference multiplied by flow.


RESULTS
We found a significant increase in estimated spillover of norepinephrine from the drainage area of the portal vein from 10 (-1.2, 78) ng x min(-1) to 27 (1.8, 475) ng x min(-1)[median (range)] (P = 0.05), but no change in estimated spillover of norepinephrine from the drainage area of the femoral vein. Plasma concentrations of norepinephrine increased in central venous and arterial blood. There was no significant change in epinephrine concentrations in arterial blood.


CONCLUSIONS
Estimated norepinephrine spillover from the drainage area of the portal vein increased during CO2-pneumoperitoneum in pigs. This may indicate that the increased norepinephrine concentrations found in arterial plasma reflects a local activation of sympathetic nerves in the region of the portal drainage area.
Myre
K
K
Department of Anesthesiology, Ullevaal University Hospital, Oslo, Norway. kirsti.myre@ioks.uio.no
Rostrup
M
M
Eriksen
M
M
Buanes
T
T
Raeder
J
J
Stokland
O
O
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D002245:Carbon Dioxide / Q000008:administration & dosage*; D002302:Cardiac Output / Q000502:physiology; D002339:Carotid Arteries / Q000502:physiology; D004195:Disease Models, Animal; D004837:Epinephrine / Q000097:blood; D005260:Female; D005268:Femoral Vein / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D008297:Male; D009638:Norepinephrine / Q000097:blood*; D011028:Pneumoperitoneum, Artificial / Q000009:adverse effects / Q000379:methods*; D011169:Portal Vein / Q000503:physiopathology*; D011651:Pulmonary Artery / Q000502:physiology; D018709:Statistics, Nonparametric; D013552:Swine; D013815:Thermodilution
D002245:Carbon Dioxide; D009638:Norepinephrine; D004837:Epinephrine