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Prevention of systemic hyperlactatemia during splanchnic ischemia
S M Jakob1, M Merasto-Minkkinen, J J Tenhunen
1Department of Anesthesiology and Intensive Care, Kuopio University Hospital, Finland.
Shock (Augusta, Ga.)
|August 18, 2000
Summary
Fluid resuscitation can mask splanchnic ischemia by preventing systemic hyperlactatemia. Hepatic lactate uptake increases with mesenteric hypoperfusion, but arterial lactate levels may not reflect true splanchnic lactate kinetics.
Area of Science:
- Physiology
- Gastroenterology
- Critical Care Medicine
Background:
- Arterial blood lactate is a marker of poor tissue perfusion.
- Splanchnic hypoperfusion can lead to increased hepatic lactate uptake, potentially masking systemic hyperlactatemia.
- Fluid resuscitation aims to maintain systemic blood volume and flow.
Purpose of the Study:
- To investigate if fluid resuscitation prevents systemic hyperlactatemia during isolated mesenteric hypoperfusion.
- To determine if systemic lactate levels accurately reflect splanchnic ischemia under these conditions.
- To analyze the relationship between mesenteric blood flow, hepatic lactate uptake, and systemic lactate levels.
Main Methods:
- A randomized study involving 7 pigs subjected to 4 hours of splanchnic hypoperfusion via superior mesenteric artery flow reduction.
- Control group of 7 pigs.
- Fluid administration to maintain pulmonary artery occlusion pressure between 5-8 mm Hg.
- Continuous monitoring of hemodynamic parameters (cardiac output, blood flows) and lactate concentrations in various blood vessels.
- Measurement of jejunal mucosal-arterial pCO2 gradients.
Main Results:
- Ischemic pigs showed decreased portal vein flow, but increased hepatic arterial flow.
- Jejunal mucosal-arterial and mesenteric vein-arterial pCO2 gradients significantly increased, indicating ischemia.
- Mesenteric and portal venous lactate levels rose significantly in the ischemic group.
- Hepatic lactate uptake increased in response to increased hepatic lactate influx.
- Arterial lactate and net splanchnic lactate uptake did not significantly change, masking the severity of ischemia.
Conclusions:
- Fluid resuscitation can prevent systemic hyperlactatemia and mask splanchnic ischemia.
- Increased hepatic lactate uptake compensates for splanchnic hypoperfusion but does not elevate systemic arterial lactate.
- Net splanchnic lactate exchange is an unreliable indicator of intestinal hypoperfusion when hepatic lactate kinetics are altered.