The purpose of this study is to determine whether the incidence of tourniquet pain is decreased if infraclavicular nerve block is administered, compared to axillary brachial plexus block, for surgical interventions at the level or distal to the elbow.

Pneumatic tourniquets are often used in orthopedic surgery to ensure bloodless surgical field. Besides their obvious positive effects, arterial tourniquets have some unfavorable properties. One of these is tourniquet pain, which can manifest in the presence of an otherwise adequate neuraxial or peripheral nerve block. If it develops, it is usually difficult to manage, and can be severe enough to necessitate conversion to general anaesthesia.

In the past the incidence of tourniquet pain, associated with different nerve blocks has been estimated in clinical trials for which it was a secondary outcome measure. One recent meta-analysis addressed the question: is infraclavicular block (ICB) associated with a lesser incidence of tourniquet pain compared to other brachial plexus blocks. The studies selected by this meta-analysis used different types of nerve block. However it did not address the clinically relevant question: using standard techniques for ultrasound guided brachial plexus block (USgBPB) is the infraclavicular approach associated with a lesser incidence of tourniquet pain than the axillary approach? The following nerves contribute to the perception of tourniquet pain: musculocutaneous, radial, medial cutaneous brachial (MCBN) and intercostobrachial (ICBN). The potential advantage of the ICB over the axillary brachial plexus block (ABPB) in regards to tourniquet pain comes from anatomical reasons. In the pyramid shaped infraclavicular space the cords are much closer to each other; thus the likelihood of achieving effective MCBN and ICBN block is greater. The infraclavicular route has proven to result in an equally effective, reliable and safe block of the brachial plexus, compared to the axillary approach. We hypothesize that the incidence of tourniquet pain is less with infraclavicular block compared to axillary brachial plexus block.

The aim of the study is, to compare the incidence and severity of tourniquet pain associated with ultrasound guided ICB and ABPB in patients undergoing orthopedic surgery at the level or distal to the elbow, with a tourniquet time longer than 45 minutes.

Inclusion Criteria:

• ASA I-III
• Orthopedic surgery at the level or distal to the elbow
• Expected tourniquet time > 45 min (K-wiring not suitable)

Exclusion Criteria:

• Contraindication of regional anaesthesia, patient is allergic to local anesthetics
• Clinically significant cognitive impairment (Minimental state score < 24)
• Chronic pain syndrome
• Preexisting nerve damage in the operated arm (sensory or motor deficit)
• Axillary clearance in the past
• History of peripheral neuropathy)
• Pregnancy