Patterns of free-radical production after tourniquet ischemia: implications for the hand surgeon.

Since use of the pneumatic tourniquet is standard procedure for the hand surgeon, ischemic and reperfusion injury is a risk. To determine optimal periods of ischemia, 100 rabbit hindlimbs were subjected to various ischemic insults and analyzed for malondialdehyde (an indicator of free-radical production). Group 1 (3 hours of continuous ischemia) had 12.5 percent more reperfusion damage than controls (p less than 0.05). Group 2 (three 1-hour ischemic insults) had 10 percent more damage than controls (p less than 0.05). Group 3 (two 90-minute ischemic episodes) had 21 percent more damage than controls (p = 0.0001). Group 4 (4 1/2 hours of continuous ischemia) had 14.5 percent more damage than controls (p less than 0.01). Group 5 (three 90-minute ischemic episodes) had 10.8 percent more damage than controls (p less than 0.01). Group 6 (6 hours of continuous ischemia) had 17.5 percent more damage than controls (p less than 0.002). Group 7 (four 90-minute ischemic episodes) had 14 percent more damage than controls (p less than 0.01). Group 8 (three 2-hour ischemic episodes) had 22.5 percent more damage than controls (p less than 0.003). And group 9 (two 3-hour ischemic episodes) had 42 percent more damage than controls (p less than 0.0001). These results suggest a direct correlation in reperfusion injury with duration of tourniquet ischemia. Additionally, allowing specific reperfusion periods in some groups ultimately increased the amount of reperfusion injury.