Flow redistribution in a hyperdynamic small animal burn: comparison to patterns in sepsis

Area of Science:

• Physiology
• Burn Medicine
• Sepsis Research

Background:

• Visceral hypoperfusion and lactate accumulation are observed in sepsis, contributing to multiple system organ failure (MSOF).
• Severe thermal injury also leads to MSOF, prompting investigation into similar circulatory derangements.

Purpose of the Study:

• To determine if severe thermal injury in rats causes a blood flow redistribution similar to that seen in sepsis.
• To assess for local lactate accumulation in visceral organs following thermal injury.

Main Methods:

• Resuscitated 50% scald burn (BURN) or sham (SHAM) procedures were performed on rats.
• Cardiac output (CO), effective hepatic blood flow (EHBF), and effective renal plasma flow (ERPF) were measured 24 hours post-injury.
• Pyruvate and lactate concentrations were analyzed in blood, liver, and skeletal muscle.

Main Results:

• Cardiac output significantly increased in BURN rats compared to SHAM (52% vs. 30.7 ml/min/100 g).
• Effective hepatic blood flow showed a smaller increase in BURN rats (18%), and effective renal plasma flow had an insignificant increase (24%).
• No significant lactate accumulation or derangement in pyruvate/lactate ratios was observed in blood, liver, or skeletal muscle of BURN rats.

Conclusions:

• Severe thermal injury induces a redistribution of blood flow, with increased cardiac output but disproportionately lower increases in hepatic and renal blood flow.
• Unlike sepsis, severe thermal injury in this model does not result in visceral organ lactate accumulation.
• The circulatory response to thermal injury differs from sepsis, suggesting distinct pathophysiological mechanisms beyond a generalized stress response.