Sympathetic blockade does not enhance tissue warming during isolated heated limb perfusion

Area of Science:

• Oncology
• Anesthesiology
• Thermoregulation

Background:

• Isolated, heated limb perfusion is a treatment for advanced melanoma.
• Sympathetic blockade via spinal anesthesia was previously used to enhance vasodilation for perfusion.
• Mild systemic hyperthermia is a newer method to induce vasodilation.

Purpose of the Study:

• To investigate if spinal anesthesia provides additional benefit for tissue warming during isolated limb perfusion when mild systemic hyperthermia is employed.
• To determine if sympathetic blockade is necessary when active thermoregulatory vasodilation is induced.

Main Methods:

• Twenty patients undergoing lower extremity perfusion were randomized to receive either general anesthesia with spinal anesthesia or general anesthesia alone.
• All patients received aggressive warming via forced air and circulating water.
• Tissue temperatures, pump flow, and time to reach target temperature were recorded.

Main Results:

• No significant differences in limb tissue temperatures were observed between the spinal and no-spinal anesthesia groups.
• Pump flow rates and the time to reach an average tissue temperature of 39°C did not differ significantly between groups.
• Sweating, indicating active vasodilation, occurred in most patients regardless of spinal anesthesia use.

Conclusions:

• Sympathetic blockade does not enhance tissue warming during isolated limb perfusion when mild systemic hyperthermia is used.
• Mild systemic hyperthermia may be sufficient to induce vasodilation, potentially negating the need for sympathetic blockade.
• Neuraxial blockade offers no added benefit for convective tissue warming in this specific clinical scenario.