Use of Ultrasound in Upper Extremity Blocks.
Condition: Regional Anesthesia
Study type: Interventional

Summary: 
      Many patients undergoing surgery on their hand receive a form of anesthetic called "axillary
      brachial plexus block". This involves the injection of local anesthetic (freezing medication)
      around the nerves that supply the upper limb, which are located in the arm pit. The technique
      currently used by physicians performing this procedure is far from perfect, and in up to 1 of
      every 5 patients it does not work well enough to allow surgery, and a different form of
      anesthetic may need to be used.

      In an attempt to improve these results, we have recently developed a new technique, using
      ultrasound imaging to "see" the nerves prior to giving the injection. Our initial results are
      very promising, implying that this may be a highly successful and safe approach. The purpose
      of this study is to determine if this technique is indeed more successful. In order to do
      that, we will ask 110 patients for their participation. They will be divided in two groups,
      at random. One group will receive the standard technique (transarterial, using a small needle
      to find the artery that is close to the nerves). The other group will receive the injection
      after identifying the nerves with ultrasound imaging. They will all receive the same type of
      medication, and they will be tested every 5 minutes for half an hour to determine if the
      block has been successful, according to pre-established criteria. Their pain control will be
      assessed after the surgery and they will be called 24 hours and 1 week after the surgery to
      assess their recovery and rule out any possible complications.
    

Detailed description: 
      Ultrasonography has been used successfully to define the anatomy of the brachial plexus in
      the interscalene, supraclavicular and axillary regions. This is a widely available
      technology, it is non-invasive, portable, less expensive than other imaging modalities and
      allows for real time imaging simultaneously with the block procedure.

      There are some recent case reports and small case series describing the use of ultrasound to
      image the brachial plexus and to guide brachial plexus blockade 16,17,18. We have used
      ultrasound imaging to succesfully identify the brachial plexus and guide needle localization
      and nerve stimulation in 15 volunteers 19. In these healthy volunteers, we were able to
      identify the brachial plexus in every subject, at four different anatomical levels :
      interscalene, supraclavicular, axillary and mid-humeral (see figures). Needle localization
      and nerve stimulation were also successful in every case. Moreover, preliminary data from an
      ongoing series at our institution, shows that when ultrasound guidance is used,
      supraclavicular brachial plexus block can be performed with a high success rate (97%)20.

      However, whether ultrasound guidance truly improves success rates when compared to more
      traditional techniques is still unknown. There has been no randomized controlled trial
      published to date addressing this question.
    

Intervention name(s): Ultrasound
Intervention type(s): Procedure
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double