Systemic reactions to tourniquet ischaemia

Area of Science:

• Orthopedic Surgery
• Anesthesiology
• Physiology

Background:

• Tourniquet use is common in knee arthroplasty.
• Systemic effects of tourniquet ischemia are not fully understood, especially in elderly patients.

Purpose of the Study:

• To investigate the systemic physiological changes following tourniquet release after knee arthroplasty.
• To assess the impact of tourniquet ischemia duration on patient hemodynamics and metabolic status.

Main Methods:

• Studied 15 patients undergoing knee arthroplasty with lumbar epidural analgesia.
• Monitored ECG, blood pressure, blood gases, serum potassium, acid-base status, and creatine-phosphokinase.
• Measured skin temperature of the operated leg during and after tourniquet application (70-135 min).

Main Results:

• Significant decrease in blood pressure post-tourniquet release due to reduced peripheral resistance.
• Significant increase in serum potassium peaking at 3 minutes after release.
• Tendency towards metabolic acidosis, linked to local lactate production.
• Progressive fall in ischemic leg skin temperature, indicating low metabolic rate.
• No evidence of myocardial, pulmonary, or local muscular injury.

Conclusions:

• Systemic changes after up to 2 hours of tourniquet ischemia are moderate and reversible.
• Elderly patients tolerate tourniquet ischemia well with no significant adverse cardiac or pulmonary events.
• Findings suggest tourniquet use is safe in this patient population.