Tourniquet timing alters foot surgery pain outcomes

By Lynda Williams, Senior medwireNews Reporter

The timing of thigh tourniquet application may affect pain control in patients undergoing forefoot surgery, research published in Foot and Ankle Surgery suggests.

The findings show that patients given ankle bock after tourniquet inflation had significantly better pain control 24 hours after surgery on a visual analog scale (VAS) than patients whose tourniquet was inflated before ankle block, at 4.5 versus 6.3 points.

Pain scores were also better in the post- than pretourniquet group 4 hours after surgery, at 2.5 versus 3.9 points, but this difference was not significant, report Vinay Kumar Singh and co-workers from Epsom and St Helier Hospital in Carshalton, UK.

"These results could be explained by our hypothesis that local concentration of anaesthetic falls due to systemic absorption in patients who had the block before tourniquet application leading to early wearing of block," they say.

This appears to counteract the predicted benefit of applying block before tourniquet - allowing the use of peripheral pulses to improve location of peripheral nerves over use of bony landmarks alone, the team explains.

Sing et al randomly assigned 60 patients undergoing Hallux Valgus reconstruction using Chevron or Scarf osteotomy to receive ankle block with 20 ml of 0.5% bupivacaine before (n=30) tourniquet application or after application, a delay of approximately 5 minutes. Patients were operated on by a single surgeon.

As well as improved VAS scores, patients given ankle block after tourniquet were less likely to require oral analgesia than pretourniquet patients both 4 hours (5 vs 30%) and 24 hours (65 vs 85%) after surgery.

The researchers say their findings show that "ankle block can be effective even when its application is solely based on anatomical land marks in absence of pulses showing that the anatomical knowledge and experience of the operating surgeon is of great importance."

They also note that their results indicate that "timing of block to tourniquet may not be as relevant in early hours but is crucial in later postoperative hours."

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