Paraneural Sheath & Fascial Compartments Surround Brachial Plexus at Supraclavicular Fossa During Selective Trunk Block
Condition: Musculoskeletal Diseases or Conditions
MeSH terms: Musculoskeletal Diseases
Study type: Observational

Summary: 
      The aim of this retrospective study is to define the paraneural (fascial) sheath and fascial
      compartments that surround the brachial plexus at the supraclavicular fossa by reviewing
      previous ultrasound images from cases that have undergone ultrasound guided selective trunk
      brachial plexus block.
    

Detailed description: 
      The optimal anatomical plane (relative to the nerve) or the "goal" for local anesthetic (LA)
      injection during an ultrasound guided (USG) brachial plexus blockade (BPB) at the
      supraclavicular fossa is currently not known. USG BPB is often described as a "subfascial",
      "extra fascial", "intracluster", "interfascial", sub-perineural", "intraneural", "corner
      pocket" or "periplexus" injection. Although this suggests that the local anesthetic is
      injected into different tissue planes or fascial compartments, even if such planes do exist,
      as seen in other regions such as popliteal sciatic nerve are not clearly defined at the
      supraclavicular fossa. However, recently with the use of high definition ultrasound imaging
      for USG Selective trunk block (SeTB) and principal investigator has often observed distinct
      paraneural (fascial) sheath and fascial compartments surrounding the brachial plexus at the
      supraclavicular fossa. These connective tissue layers are also better delineated after the
      local anesthetic injection. The principal investigator believes these may be the connective
      tissue layers that previous researchers have referred to in different reports. Currently
      there are no published data demonstrating the paraneural sheath and fascial compartment
      surrounding the brachial plexus in-vivo. Principal investigator believes that this fascial
      layer and compartment influence the spread of LA during USG BPB around the individual
      elements of the brachial plexus at the supraclavicular fossa and therefore, these anatomical
      structures have to be delineated so as to improve the safety, success and quality of USG BPB.
      This study will involve reviewing archived high definition ultrasound images in audio video
      interleave format from all adult patients who had undergone USG SeTB for surgical anesthesia
      during upper extremity surgery from January 1, 2020 to June 30, 2021 to define the paraneural
      sheath and fascial compartments that surround the brachial plexus at the supraclavicular
      fossa.
    

Intervention name(s): Ultrasound guided Selective trunk block
Intervention type(s): Procedure
Intervention description(s): High definition ultrasound images that were acquired during USG SeTB are routinely stored in the hard disk of ultrasound machine in DICOM (Digital Imaging and Communications in Medicine) format will be used for this review. The images of principal investigator's previous research studies with Clinical trial registration: NCT04752410 and NCT04773405 will also be retrieved. The ultrasound imaging was performed before (scout scan), during and immediately after the USG SeTB. As is the principal investigator's standard practice, all ultrasound scan was performed in a sequential manner (SUIT: Sequential Ultrasound Imaging Technique) with the orientation marker of the transducer directed laterally so as to obtain a transverse oblique view of the brachial plexus block at the supraclavicular fossa. Approximate 50 cases who had undergone USG SeTB for surgical anesthesia during upper extremity surgery since January 1 2020 to June 30, 2021 will be evaluated by two anesthesiologists.
Other intervention name(s): Ultrasound imaging
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Dataset of previous research titled "Selective Trunk Block: A Prospective Non-Randomized
        Study of Intervention" (approved by the Joint CUHK-NTEC CREC; CREC Ref no: 2020.687-T;
        Clinical trial registration: NCT04752410) and " Minimum Effective Local Anaesthetic Volume
        of a 1:1 Mixture of 2% Lidocaine with 5 µg/ml of Epinephrine and 0.5% Levobupivacaine
        Required for Ultrasound Guided Selective Trunk Block: A Dose Finding Study" (approved by
        the Joint CUHK-NTEC CREC; CREC Ref no:2020.680-T; Clinical trial registration: NCT04773405)
        will also be retrieved.
      
Keywords: Selective Trunk block