The Effects of a Tourniquet on Serum Catecholamine Levels for General and Spinal Anesthesia in Total Knee Replacement / 대한마취과학회지

ABSTRACT

BACKGROUND: Pneumatic tourniquets are most frequently used during operations on the lower extremities, especially during knee operations, and provide a bloodless surgical field and prevent excessive blood loss. But tourniquets increase blood pressure, though the cause has not been identified. We thought that plasma catecholamine is increased by pneumatic tourniquet inflation. Troponin I is specific cardiac marker in myocardiac injury. So we measured plasma catecholamine and Troponin I under general and spinal anesthesia in patients undergoing total knee replacement. METHODS: We divided the patients into two groups, the first group (Group I, n = 25) was the general anesthesia group and second group (Group II, n = 26) the spinal anesthesia group. All patients underwent an operation for total knee replacement. Serum enzyme levels are instable so we tried to keep changes at a minimal level. Thus all operations were carried out by the same group of surgeons, in the same operating room, at the same time (AM 800 start operation). The same tourniquet was applied for all subjects (tourniquet pressure 350 mmHg, 9 cm width). Group I patients had general anesthesia with N2O - O2 - Enflurane. Group II patients had spinal anesthesia with 0.5% tetracaine the dermatomal level of sensory blockade to pin-prick was T6 - T4. We measured blood pressure, heart rate, SpO2, ECG, serum catecolamine and trophonine I. Blood sampling were performed preoperation, 50 minutes after tourniquet application, and 30 minutes after operation to obtained serum catecholamine and trophonine I levesl. Result: Mean arterial pressure increased in group I during tourniquet inflation. The serum catecholamine level was higher in group I than in group II. The serum troponin I level was statistically significance in the general anesthesia groups (Group I). CONCLUSIONS: It might be suggested that an increased level of serum catecholamine causes tourniquet induced hypertension. Myocardial injury due to tourniquet induced hypertension was not affected by anesthesia type