THE PROVIDER

• Strong knowledge of anatomy
• Appropriate training
• Appropriate assistance

PATIENT FACTORS: ELIGIBLE FOR BLOCK?

• Type of surgery  
  • Choose the appropriate block (+/- catheter or additives)
• Contra-indications for LRA techniques
• Relevant comorbidities which can make regional techniques more difficult
• Conditions that make US imaging difficult: e.g. cerebral palsy – contractures, long-term wheelchair dependence, muscle atrophy (poor muscular structures on US)
• Conditions that make central blocks difficult: Scoliosis
• Conditions that make peripheral nerve block (PNS) techniques difficult: myotonia, use of neuromuscular blocking agents, Ehlers Danlos (a block can also cause skin damage), hereditary sensory and motor neuropathy (HSMN) 1 and 2 (may require higher mA when using PNS technique with a nerve stimulator)
• Previous LRA experience 
• Neuromuscular conditions (assess and document before performing the block) 
• History of chronic pain in area to be operated on; consider LA catheter /additives
• Patient on baclofen: increased risk of muscle spasm postoperatively: consider LA catheter/additives
• Sometimes longer analgesia is desired to facilitate physiotherapy: consider LA catheter/additives

NB: Before placing a catheter, consider where they will be nursed postoperatively. Consider use of spica/casts when considering catheter exit site.

The extent of surgery is not always known beforehand. Sometimes it is better to provide  intraoperative intravenous analgesia/do a single shot block and perform/repeat the appropriate block at the end of the surgery.

PREOPERATIVE CONSULTATION

NB: Generally, the more peripheral a block is, the better the risk-benefit balance,  and thus more acceptable to the patient and parents/carers.

In older children having minor surgery the operation may be done awake; have EMLA applied to the block injection site (you may wish to scan the patient on the ward prior to this). If a parent/carer is going to attend, ensure they know what their job is in the anaesthetic room i.e., distracting their child during the proceedings. Ensure a nurse will be attending the procedure to support the patient and the parent/carer.

IN ANAESTHETIC ROOM

• Full and appropriate (AAGBI) monitoring, secured airway and IV access
• If prophylactic antibiotics indicated for surgery, then administer prior to the block
• Position patient safely in block position
• Consider ergonomics:
  • Position yourself and the ultrasound machine to align your needle, ultrasound probe,  the targeted area on the patient and the ultrasound image in a single straight line
  • The comfort of the operator will increase the likelihood of a successful block: consider whether to sit or stand, the appropriate bed height and the position of the patient. Ensure you stand square, keep shoulders perpendicular to the needle, elbows close to your sides; this all reduces the tendency to drift out of alignment
• Assess surface anatomy
• Choose appropriate ultrasound probe and block needle
• For all blocks: wear sterile gloves and use a probe cover
• For continuous catheter techniques and more central blocks: full aseptic technique is required (hat, mask, gown, gloves), sterile probe cover

GETTING READY

• Clean a large area around the desired injection site (e.g., a 2% chloroprep stick) and drape the patient exposing a large enough area to allow scanning up and down the nerves
• Allow the area to dry completely
• Choose appropriate % LA. Do NOT draw up more than the maximum dose
• Connect the extension to the needle, ensure all the kit is flushed through – air bubbles distort the ultrasound image. If using a catheter, flush to ensure patency
• Consider the use of adjuvants

NB: usually 0.25% levobupivacaine (or 0.2% ropivacaine) is used, 0.5% is appropriate for ring blocks, penile blocks and for lower limb surgery where  there is  high risk of postoperative muscle spasm.

Use a lower concentration (e.g., 0.125% levobupivacaine or 0.1% ropivacaine) if there is high risk of compartment syndrome or local anaesthetic toxicity (e.g., neonates)

If concerned about the volume of LA available due to the small size of patient (< 10kg), draw up a separate syringe with saline to use as a ‘seeker solution’ to ensure needle tip position before injecting LA. This will avoid wasting LA due to incorrect needle position.

When performing a central block or inserting a regional catheter, a full surgical scrub is necessary (gown, gloves, mask, …)

ULTRASOUND IMAGING

• Choose appropriate probe (usually high frequency linear, though a curvilinear is preferred for deeper blocks in larger patients e.g., Anterior Quadratus Lumborum block). Choose the highest frequency appropriate for the estimated depth of the block
• Orientate probe and image, set the depth greater than the expected target depth
• Optimise the gain (vessels must be black and the rest uniform grey) 
• Use sterile US gel to provide an air free interface (remove gel prior to needling)
• Perform a mapping or scout scan to assess the anatomy and identify the target

NB when sliding up and down with the probe, allow the ulnar side of you hand to maintain contact with the patient. This will give you more control over your scanning and prevents the probe from slipping off. Tilting the US probe cranially or caudally can make the nerve easier to visualise (this allows for the anisotropic behaviour of the nerve)

NEEDLING

• Perform a “Prep Stop Block” or “STOP BEFORE YOU BLOCK”
• For in-plane techniques (IP): Place the target in the lower corner opposite to the needle entry point, ensure your needle tip is always visible when advancing the needle towards the nerve. Aim for the 6 o’clock position (= deep to the nerve), aspirate, then slowly inject LA. The LA will show as darker spread around the nerve. If, when half of the LA is injected, the nerve does not look surrounded, it may be necessary to withdraw the needle and inject the 2nd part of the LA at the 12 o’clock position (superficial to the nerve).
• For out-of-plane techniques (OOP): place the target in the middle of the screen. The targets will be 3 o’clock and/or 9 o’clock (either side of the nerve). Follow your needle tip. Always aspirate before injecting.
• For large nerves (e.g. the sciatic) a “doughnut sign” is desirable. This is not necessary for smaller nerves
• Insert the needle with bevel facing towards the ultrasound probe

Where possible try not to contact the nerve with the needle, this can often be achieved by getting into a fascial plane close by, then allowing the injectate to actively be pushed towards the nerve.

If you lose the view of the needle, stop immediately and check your probe and needle orientation. Use your probe to find your needle tip while keeping your needle immobile. Do NOT try to move your needle towards the ultrasound beam.

INTRAOPERATIVELY

• Assess any deficiencies in the block: observe changes in HR, BP and RR; avoid using anaesthetic agents (e.g., opioids) that may obscure assessment (especially true in children with special needs where pain will be very hard to assess in recovery - you need to know your block works/doesn’t work)
• Ensure systemic analgesia is provided for procedures where the block does not cover visceral pain (e.g., rectus sheath block for pyloromyotomy)
• Consider systemic analgesic adjuvants (e.g., MgSO4, dexamethasone, NSAIDS, alpha-2-agonists)