Pathophysiologic effects distal to a tourniquet in the dog

Area of Science:

• Physiology
• Surgical Research

Background:

• Pneumatic tourniquets are used in surgery to reduce bleeding.
• Prolonged tourniquet application can lead to ischemia and tissue damage.

Purpose of the Study:

• To quantitate the effects of tourniquet ischemia on intramuscular tissue gases and pH.
• To determine the critical duration of tourniquet application to avoid significant pathophysiologic changes.

Main Methods:

• Monitoring of intramuscular partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), and pH in a canine hindleg model.
• Assessment of creatine phosphokinase (c.p.k.) and lactic acid levels.
• Histologic examination of muscle tissue.

Main Results:

• Severe tissue hypoxia, hypercarbia, and acidosis were observed distal to the tourniquet.
• Recovery time for tissue gases increased with tourniquet duration.
• Elevated c.p.k. and lactic acid, along with early signs of muscle degeneration, were noted after 1-2 hours of ischemia.

Conclusions:

• Tourniquet-induced ischemia exceeding 1 to 1.5 hours leads to significant pathophysiologic tissue changes.
• Intermittent tourniquet release (10 minutes per hour) can mitigate complications during prolonged ischemia.