This study evaluates the influences of the status of sympathovagal balance before tourniquet deflation on a decrease in arterial blood pressure following the deflation during total knee replacement arthroplasty

Patients present with different hemodynamic profiles after intraoperative tourniquet deflation during total knee replacement arthroplasty.

Sympathovagal balance can be measured before tourniquet deflation and might determine the hemodynamic response to tourniquet deflation.

Inclusion Criteria:

1. American Society of Anesthesiologists physical status I - II
2. Body mass index < 35 kg/m2

Exclusion Criteria:

1. Coagulation deficiencies
2. Known allergies to local anesthetics
3. Neurologic deficit on the side being operated on
4. Inflammation at the lumbar puncture site
5. Cardiac conduction disorders or arrhythmias
6. Congestive heart failure
7. Serum electrolyte abnormalities
8. Psychiatric disorders
9. Patient's refusal
10. Difficulty communicating with medical personnel
11. Severe hypovolemia
12. Increased intracranial pressure
13. Severe aortic stenosis
14. Severe mitral stenosis

Patients undergoing total knee replacement arthroplasty in a tertiary university hospital