Bier's block - iv regional anaesthesia for LAMPs

see also:

• local anaesthetic agents
• fractured distal radius in children
• orthopaedics in the ED
• EDTeaching.com's video on Bier's blocks
• https://www.rch.org.au/clinicalguide/guideline_index/Bier_block/

• LAMP is an abbreviation (Local Anaesthesia Manipulation and Plaster) for a procedure performed on a fractured bone or dislocated joint, where it is manipulated with the aid of a local anaesthetic
  • anaesthesia options include:
    • iv regional anaesthetic agent “Bier's block” where the local anaesthetic (either lignocaine or prilocaine) is injected into a vein preferably distal to the fracture whilst a proximal tourniquet remains in place for at least 25-30min
    • haematoma block
    • brachial plexus regional block
• GAMP is a manipulation and plaster immobilisation performed under general anaesthetic rather than local anaesthetic
  • although usually performed in an operating theatre, the term may also be loosely applied to procedures performed in ED with procedural sedation such as with:
    • nitrous oxide 70% inhaled
    • iv ketamine
    • iv propofol

• this depends upon:
  • availability of experienced staff and resources to perform the procedure safely
  • impact on ED patient flow
  • age of patient - children under 5 yrs rarely tolerate a Bier's block
  • difficulty of fracture to manipulate vs experience of staff in manipulation
  • ability to gain iv access in both arms with the one on the side of the fracture placed distal to the fracture
    • some children are too needle-phobic, hysterical or difficult to cannulate twice to allow this
  • ability of patient to cope with Bier's block
    • tired children in pain do not tolerate prolonged tourniquets well and thus it is probably prudent to avoid Bier's blocks on children overnight - these children may be best placed in a plaster slab with strict immobilisation for delayed LAMP or GAMP in the morning.
  • factors which would mandate general aneasthesia such as:
    • open fractures requiring formal irrigation
    • fractures requiring internal fixation to stabilise:
      • displaced intra-articular fractures
      • multiple fractures eg. supracondylar fracture and distal radius fracture on the same limb
    • bilateral fractures requiring manipulation
  • Contra-indications to intravenous local anaesthetics:
    • allergy to LAs
    • unstable epilepsy
    • severe liver disease
    • sickle cell disease
    • 2nd or 3rd degree heart block
    • severe vascular disease
    • severe hypertension - systolic > 175mmHg
    • severe crush injury
    • supracondylar fractures are NOT suitable for Bier's block due to proximity to tourniquet and inability to assess neurovascular status after manipulation.

• record patient weight
• baseline vital observations
• patient or parental informed consent after explaining the procedure and its risks, and potential for failure and resultant need for GAMP, as well as the need for follow up Xrays and possible delayed GAMP in 1-2 weeks if the fracture should slip
• confirm patient fit for the procedure including fasting status (most prefer 4 hours fast prior), and need for adjunctive iv opiate analgesia.
• if a child, apply EMLA cream or similar topically 30-60min prior to allow less painful iv access
• insert iv cannulae in each arm with the one on the injured limb distal to the fracture
• check tourniquet system
• prepare drugs:
  • local anaesthetic agents:
    • prilocaine 0.5% - draw up 0.5ml/kg into syringe(s) max 40mL, or
    • lignocaine
  • consider adjunctive iv fentanyl as a pre-med 5 min prior to assist with discomfort of tourniquet as well as residual fracture site pain.
  • consider adjunctive 50-70% nitrous oxide for particularly distressed children
• check resuscitation equipment available (eg. oxygen, suction)
• preferably use oxygen saturation monitor, particularly if usinng adjunctive agents
• if planning on using an image intensifier:
  • ensure image intensifier is available and set up
  • ensure radiographer is available (or other licensed operator)
  • ensure lead gowns are available to cover patient as well as staff

• apply several layers of Webril or Velband around upper arm of the affected limb to provide padding under the tourniquet and reduce risk of tourniquet not transmitting the desired pressure to the arm.
• apply tourniquet cuff to upper arm of affected limb with the connection tubing facing proximally - away from the forearm so it doesn't interfere with plaster application.

• check cuffs for leakage and adequate tourniquet effect:
  • inflate cuff to desired pressure (usually at least 100mmHg higher than patient's systolic BP) but less than 300mmHg
  • check machine's manometer to ensure pressure is maintained and there is no leak
  • confirm absence of patient's radial pulse to ensure adequate tourniquet effect
• deflate cuff
• if using double cuffs, repeat above with each individual cuff

• consider giving a titrated dose of iv fentanyl (eg. 0.25-0.5mcg/kg) at this stage by slow iv injection in the contralateral arm

• exsanguinate arm as much as possible to improve effectiveness of LA block and decrease discomfort
  • elevate limb for 1-2 minutes whilst using your finger to compress brachial artery
• inflate cuff
  • if using double cuffs, inflate PROXIMAL cuff ONLY if you intend to possibly deflate it during procedure
    • then later if there is excessive tourniquet discomfort, one can inflate the distal cuff over the anaesthetised upper arm, and then deflate the more painful proximal cuff
    • however, there is a risk both cuffs will be deflated, and thus it may be safer to either only use single cuff or inflate BOTH proximal and distal cuffs of double cuff tourniquets and leave them inflated.
• re-check for leakage and adequate tourniquet effect
• optionally apply a normal venipuncture tourniquet just proximal to fracture to try to localise the LA to fracture site
• slowly inject local anaesthetic agent as determined above
  • warning: injections in cubital fossa veins are less likely to be effective and more likely to cause systemic toxicity and seizures.
• the limb will become mottled - this is normal

• remove iv cannula on the injured side and apply firm pressure over iv site for at least 5min until it stops oozing as it tends to ooze longer than normal
  • there is little advantage of leaving this cannula in situ as it is rare to need a second dose of iv local anaesthetic, and the prolonged oozing may compromise your timely plaster application.
  • NB. the contralateral iv cannula MUST be left in-situ until well after the Bier's block is finished to enable treatment of complications such as seizures and to provide adjunctive analgesia if needed.

• wait until LA block is satisfactory (usually 6-10min from injection) before allowing manipulation to be performed.
• perform image intensifier (II) radiologic confirmation of adequacy of reduction
• apply 1st rolls of below elbow plaster of paris ensuring:
  • appropriate forearm position (pronation vs supination)
  • metacarpals are not squashed together - have assistant hold 2nd and 5th fingers only whilst plastering takes place
  • adequate 3 point moulding of the plaster to minimise risk of fracture position slipping
  • plaster is not too proximal that it will impact on cubital fossa on flexion of elbow to 90deg
  • plaster does not extend too distally around base of thumb and across palm, particularly check the ulnar aspect as too distal plaster can cause digital nerve neuropraxia to the 5th finger.
• consider re-checking position using the II before completing the below elbow plaster if position satisfactory.
• if position inadequate and time allows and patient tolerant, remove plaster and re-manipulate.

• cuff should remain inflated for at least 20min after injection of prilocaine to minimise risk of systemic LA toxicity (eg. seizures) but becomes increasingly uncomfortable after 30min duration.
• deflate cuffs and carefully watch patient for systemic toxicity of LA (eg. neurologic features such as tinnitus, circum oral paraesthesiae which are signals to temporarily re-inflate cuffs to avoid seizure or cardiac toxicity, although these are rare).
• after 5-10min, if no complications, cuffs can be removed along with under-padding
• if patient is a child, complete the above elbow section of the plaster with elbow at 90deg and forearm in correct position (eg. pronated or supinated), ensuring plaster does not dig into cubital fossa
  • tip: apply plaster with elbow flexed slightly more than 90deg and then when bringing elbow to 90deg, the plaster is pulled away from the cubital fossa.
• patient should be closely observed for at least 30 minutes after cuff deflation
• arrange post-reduction Xray
• ensure patient is given plaster instructions including strict elevation for 24-48hrs after a LAMP and plaster check next day to ensure plaster does not need splitting.
• arrange follow up and Xray within 1 week