Describe the use of the tourniquet in a total knee arthroplasty and its hemodynamic consequences

Describe the use of the tourniquet in a total knee arthroplasty and its hemodynamic consequences.

The use of a tourniquet in a total knee arthroplasty is standard and is used to minimize blood loss. Inflation of the tourniquet can be quite painful and therefore, needs to be considered in the anesthetic plan. General, neuraxial, and regional anesthesia provide excellent relief from tourniquet pain. The tourniquet is usually set to an infla-tion pressure above the patient’s blood pressure, com-monly 350 mmHg for the lower extremity. The inflation time is usually limited to 2 hours of continuous use. Longer tourniquet times can result in a metabolic acidosis and ischemic changes in the operative limb.

The release of the tourniquet results in a transient sys-temic metabolic acidosis and increase in arterial carbon dioxide. A small increase in heart rate, drop in blood pres-sure, and rise in serum potassium may also be noted. It is prudent to administer a fluid bolus prior to tourniquet release. Usually these changes result in no adverse effects to the patient.