Assessment of graded intestinal hypoperfusion and reperfusion using continuous saline tonometry in a porcine model.
OBJECTIVE
To evaluate effects of graded intestinal hypoperfusion and reperfusion on intestinal metabolic parameters as assessed by a modified continuous saline tonometry technique.


METHODS
Twelve barbiturate-anaesthetized female pigs.


METHODS
Measurements were performed prior to and during three predefined levels of superior mesenteric mean arterial blood pressure (P(SMA) 70, 50 and 30 mmHg, respectively, each 80 min long), obtained by an adjustable clamp around the origin of the superior mesenteric artery, and during reperfusion. We continuously measured jejunal mucosal perfusion (laser Doppler flowmetry), jejunal tissue oxygen tension (PO(2TISSUE); microoximetry) and intramucosal PCO(2) (continuous saline tonometry) and calculated net intestinal lactate production, mesenteric oxygenation, PCO(2) gap (jejunal mucosal PCO(2)-arterial PCO(2)) and pHi.


RESULTS
At P(SMA) 70 and 50 mmHg mesenteric oxygen uptake and net lactate production remained unaltered, in spite of decreased oxygen delivery. At these P(SMA) levels PCO(2) gap increased, while pHi and PO(2TISSUE) decreased. At P(SMA) 30 mmHg pronounced increases in PCO(2) gap and mesenteric net lactate production as well as marked decreases in PO(2TISSUE) and pHi were demonstrated. Data indicate absence of anaerobic conditions at an intestinal perfusion pressure (IPP)> or =41 mmHg, a pHi> or =7.22 or PCO(2) gap< or =15.8 mmHg.


CONCLUSIONS
Continuous saline tonometry detected intestinal ischemia as induced by graded reductions in IPP. A threshold could be defined above which intestinal ischemia does not occur.
Fröjse
R
R
Department of Surgical and Perioperative Sciences, Anesthesiology and Intensive Care, Umeå, University Hospital, Umeå, Sweden.
Lehtipalo
S
S
Winsö
O
O
Johansson
G
G
Biber
B
B
Arnerlöv
C
C
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000098:blood supply; D008365:Manometry; D017538:Mesenteric Artery, Superior / Q000378:metabolism; D023421:Models, Animal; D008955:Models, Cardiovascular; D010101:Oxygen Consumption / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D015424:Reperfusion; D012720:Severity of Illness Index; D012965:Sodium Chloride / Q000494:pharmacology*; D013552:Swine; D014655:Vascular Resistance / Q000502:physiology
D012965:Sodium Chloride