Gut luminal lactate release during gradual intestinal ischemia.
OBJECTIVE
Gut ischemia induced by occlusion of the superior mesenteric artery (SMA) results in release of lactate into the gut lumen. We studied the threshold of SMA flow reduction that leads to increased gut luminal lactate during stepwise reduction in SMA blood flow.


METHODS
A randomized, controlled animal experiment in a university experimental research laboratory.


METHODS
Anesthetized, normoventilated, normovolemic domestic pigs were randomized to ischemia ( n=7) and sham groups ( n=7). SMA blood flow was reduced stepwise at 15-min intervals by 22%, 44%, 66%, and 88% and kept constant thereafter for 60 min.


RESULTS
Jejunal luminal microdialysate lactate and mucosal pCO(2) were measured every 15 min. The luminal lactate increased over the upper normal limit of 0.2 mmol/l at a median SMA blood flow of 9.6 ml kg(-1) min(-1) (range 7.5-23.7). In five of seven animals the increase in luminal lactate was preceded by or accompanied by an increase in the mucosal-arterial pCO(2) gradient.


CONCLUSIONS
There is a threshold of SMA blood flow below which gut luminal lactate increases, indicating mucosal anaerobic metabolism. Measurement of gut luminal lactate by microdialysis can be used to assess the adequacy of gut perfusion and the onset of anaerobic metabolism.
Tenhunen
J J
JJ
Critical Care Research Program, Division of Intensive Care, Department of Anesthesiology and Intensive Care, Kuopio University Hospital, P.O. Box 1777, 70211 Kuopio, Finland. jyrki.tenhunen@kuh.fi
Jakob
S M
SM
Takala
J A
JA
D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D005260:Female; D006439:Hemodynamics; D007413:Intestinal Mucosa / Q000098:blood supply*; D007511:Ischemia / Q000175:diagnosis / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism*; D008365:Manometry; D008641:Mesenteric Vascular Occlusion / Q000378:metabolism; D017551:Microdialysis; D010313:Partial Pressure; D011897:Random Allocation; D012044:Regression Analysis; D013152:Splanchnic Circulation; D018709:Statistics, Nonparametric; D013552:Swine
D002245:Carbon Dioxide; D019344:Lactic Acid