Systemic and regional effects of experimental gradual splanchnic ischemia.
OBJECTIVE
We evaluated the effects of gradual intestinal ischemia on systemic and regional haemodynamics and oxygen transport.


METHODS
Superior mesenteric artery (SMA) blood flow was decreased by 40%, 70%, and 100% for 60-minute periods and thereafter released in 12 pigs. Hemodynamic changes were monitored continuously, and the intestinal perfusion was evaluated by changes in portal vein-arterial lactate gradient, intramucosal pH, tonometric Pco2, tonometric-portal vein Pco2 gradient, and regional oxygen extraction.


RESULTS
Local signs of intestinal hypoperfusion developed during the SMA occlusion. Intramucosal pH and portal vein pH decreased from 7.18 +/- 0.04 to 6.81 +/- 0.04 (P < .01) and from 7.36 +/- 0.01 to 7.25 +/- 0.03 (P < .05), respectively. Intramucosal Pco2 and tonometric-portal vein Pco2 gradient increased from 12.4 +/- 1.3 to 21.2 +/- 1.8 kPa (P < .01) and from 6.0 +/ 1.3 to 14.0 +/- 1.9 kPa (P < .05), respectively. Portal vein-arterial lactate gradient and splanchnic oxygen extraction increased from 0.02 +/- 0.07 to 2.32 +/- 0.47 mmol/L (P < .01) and from 0.44 +/- 0.03 to 0.60 +/- 0.03 (P < .05), respectively. Systemic changes observed during the SMA occlusion were reduction of cardiac index (161 +/- 12 to 114 +/- 8 mL/min/kg, P < .01) and pulmonary capillary wedge pressure (4 +/- 1 to 3 +/- 1 mm Hg) and increase in heart rate (124 +/- 5 to 173 +/- 11 beats/ min, P < .01) and mean arterial pressure (79 +/- 3 to 104 +/- 5 mm Hg, P > .01). Systemic oxygen extraction increased (P > .05), arterial pH increased (P < .05), and arterial lactate decreased (P < .01) during the SMA occlusion. Splanchnic ischemia defined as an increase in portal vein-arterial lactate gradient above mean +2 SD of the baseline occurred at 93 +/- 15 minutes corresponding 70% SMA occlusion.


CONCLUSIONS
We conclude that signs of tissue hypoperfusion started to develop at 70% SMA occlusion and that regional tissue hypoperfusion in the splanchnic region may develop without any systemic signs of oxygen supply/demand mismatch.
Heino
A
A
Department of Surgery, Kuopio University Hospital, Finland.
Hartikainen
J
J
Merasto
M E
ME
Koski
E M
EM
Alhava
E
E
Takala
J
J
D006439:Hemodynamics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000737:chemistry / Q000378:metabolism; D007422:Intestines / Q000098:blood supply; D007511:Ischemia / Q000378:metabolism*; D019344:Lactic Acid / Q000097:blood; D008638:Mesenteric Arteries / Q000503:physiopathology*; D010101:Oxygen Consumption; D011169:Portal Vein / Q000737:chemistry / Q000378:metabolism; D013152:Splanchnic Circulation
D019344:Lactic Acid