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See alsoÌýÌýÌýÌýÌýÌýÌý

Acute pain management
Communicating procedures to families
Local anaesthetic poisoning

Key points

1. Regional anaesthesia of the femoral nerve provides rapidly effective, medium duration anaesthesia for femoral fractures and superficial injuries to the anteromedial thigh
2. Fascia iliaca block targets the femoral nerve via the fascia iliaca compartment with reduced risk of direct injury of the femoral neurovascular bundle
3. Ultrasound-guided blocks are safer than using landmark anatomy if equipment and expertise are available
4. Intralipid should be readily available to any clinician performing regional anaesthetic blocks in case of local anaesthetic systemic toxicity

Background

• Femoral fractures cause severe pain which is exacerbated during necessary transfers and the application of skin traction
• The femoral nerve can be blocked by direct infiltration around the nerve or via the fascia iliaca compartment in which the nerve sits, allowing infiltration further away from the nerve and vessels
• Blockade of the femoral nerve by either method provides good analgesia for femoral fractures and wounds of the anteromedial thigh, reducing the need for opiates and allowing for pain-free transfers and application of traction
• The fascia iliaca block is as effective as the femoral nerve block, is simpler to perform, and has a lower risk profile, since the injection site is further away from the femoral neurovascular bundle
• This CPG describes the different methods of infra-inguinal fascia iliaca compartment block of the femoral nerve: the landmark and ultrasound-guided (in-plane and out-of-plane) techniques

Indications

• Femur fractures
• Anteromedial thigh wounds requiring exploration and washout or initial cleaning and dressing prior to theatre

Contraindications

• Local anaesthetic allergy/anaphylaxis
• Open wound or signs of infection at injection site
• Bleeding disorders or anticoagulant therapy (relative contraindication)

Potential complications

• Block failure
• Local anaesthetic allergy or anaphylaxis
• Femoral nerve trauma from needle or high-pressure infiltration of local anaesthetic
• Vascular injury resulting in a pseudoaneurysm
• Intravenous or intra-arterial infiltration resulting in local anaesthetic poisoning
• Pre-administered analgesics (especially opioids) may cause significant respiratory depression after removal of the painful stimulus by a successful nerve block

Equipment

Common to all techniques

• Monitoring:
• Pulse oximeter
• Continuous cardiac monitoring
• Cycling non-invasive blood pressure measurements
• Sterile drapes, dressing pack and gloves
• Chlorhexidine solution
• Minimum volume extension tubing
• Relevant splint/traction equipment, for application once the neural blockade has taken effect
• Resuscitation equipment including 20% lipid emulsion (Intralipid®) should be readily available in case of local anaesthetic systemic toxicity

Landmark technique

• Blunt needle (eg specific nerve block needle) to feel passage through fascial planes, but any needle may be used

Ultrasound guided technique

• Ultrasound machine with high frequency linear transducer (eg 10-15 MHz)
• Sterile probe cover
• Needle for injection
  • Specific nerve block needle, or
  • Any needle of sufficient length can be used since ultrasound-guidance should prevent the needle tip from causing direct damage to the femoral nerve/vessels, provided the needle tip is kept within view on ultrasound

Analgesia, sedation, anaesthesia

• Supplementary analgesia or sedation (eg topical local anaesthetic creams, fentanyl and/or nitrous oxide) may be required if the child is agitated or there is difficulty positioning the lower limb
• Short-acting local anaesthetic for skin infiltration and/or topical anaesthetic
  • Lignocaine with or without adrenaline (1-2 mL)
• Long-acting local anaesthetic for nerve block (duration varies widely by concentration, dose and site of injection; duration ranges below are therefore generalised)
  • Ropivacaine: onset 15-30 minutes, duration 3-10 hours
  • Levobupivacaine: onset 15-30 minutes, duration 3-10 hours
  • Bupivacaine: onset 15-30 minutes, duration 3-10 hours
• Levobupivacaine and ropivacaine are generally considered safer than bupivacaine if there is more than one option available. The Australian Medicines Handbook does not give doses for bupivacaine in paediatric patients
• Once the long-acting local anaesthetic is drawn up, it should be diluted with normal saline to double the volume, thereby increasing the spread of the anaesthetic agent.Ìý

Ìý>> Dilute with 0.9% sodium chloride to a volume of 0.8 mL/kgÌý

Procedure

• Fascia iliaca block can be performed using landmark or ultrasound-guided techniques
• Requires a good volume of anaesthetic to fully bathe the femoral nerve (see above table for recommended volumes)

Landmark technique

The femoral nerve lies in a compartment bounded anteriorly by the fascia of the iliacus muscle. It can be accessed rapidly using a landmark-based technique

1. Divide the distance between the (anterior superior iliac spine) ASIS and pubic tubercle into thirds
2. The needle entry point is 1-2 cm caudad to the estimated division between middle and lateral thirds
3. If using local anaesthetic for the skin, inject 1-2 mL and wait for effect
4. Insert the needle, taking care not to penetrate deeper than the dermal or subcutaneous layers initially
5. Once through the skin, turn the needle perpendicular to the skin surface and advance posteriorly, feeling for two separate ‘pops’ as the needle passes through the fascia lata and then the fascia iliaca
6. Aspirate to check for accidental vascular puncture
7. If no blood aspirated, slowly inject the calculated dose of local anaesthetic checking for early signs of toxicity (eg perioral tingling)

Tips:

• The pressure required to penetrate the skin is higher than that required to penetrate fascial planes, so care must be taken not to pass through fascial planes as well when entering the skin
• Holding the skin taught and inserting the needle at a 45-degree angle can help prevent accidental deep penetration
• If unsure, bring the needle tip back to just below the skin surface before advancing again, feeling for fascial ‘pops’
• The volume of anaesthetic needs to be injected completely underneath, but as close to the underside of the fascia iliaca as possible, to remain within the fascial compartment but not intramuscularly
• It is good practice to aspirate after every few mL infiltrated, checking for blood to ensure no intravascular injection

Ultrasound-guided techniques

• Ultrasound-guidance can be used to deliver the anaesthetic into the fascial compartment, away from the femoral nerve and vessels
• Ultrasound-guided techniques can be classified by anatomical relation to the inguinal ligament (supra-inguinal or infra-inguinal)
• Supra-inguinal techniques are closer to the pelvic cavity and its contents, such as bowel, are considered a more advanced technique and are not described here
• Infra-inguinal fascia iliaca blocks can be performed in-plane or out-of-plane
• In-plane describes ultrasound-guided blocks where the needle and transducer are in the same plane allowing visualisation of the whole needle under the transducer
• Out-of-plane describes ultrasound-guided blocks where the needle and transducer are in perpendicular planes and only a cross-section of the needle underneath

ÌýUltrasound-guided in-plane technique

1. Prime the needle and minimum volume extension tubing with the local anaesthetic, making sure there is no air in the needle tip
2. Hold the transducer with non-dominant hand and the needle with dominant hand
3. Find the ASIS and pubic tubercle and place the transducer over the inguinal ligament, with the lateral end of the transducer lying on the ASIS. The probe marker should be pointing to the patient’s right
4. Slide the probe towards the pubic tubercle and identify the key structures:
   • iliopsoas (iliacus and psoas major)
   • neurovascular structures (lateral to medial)
     1. femoral nerve
     2. femoral artery
     3. femoral vein
        Ìý
        
        
5. Once the key structures have been identified, slide the transducer back towards the ASIS until the femoral vessels are only just in view at the edge of the screen
   
   
   
   
6. Sweep the transducer 1-3 cm caudally, moving it distal/caudal from the inguinal ligament, keeping the femoral vessels visible at the side of the screen Ìý
   
   
   
   
7. Distal to the ASIS, sartorius becomes visible on-screen and should not be mistaken for iliopsoas
8. If using local anaesthetic for the skin, inject 1-2 mL at the lateral end of the transducer and wait for effect
9. Insert the needle under the lateral end of the transducer pointing medially and watch as the needle comes into view under the transducer
10. Advance the needle under direct vision as it passes beneath the fascia lata and fascia iliaca
11. Keep the needle within a few mL of the fascia iliaca
12. Maintain direct vision of the needle tip and ask an assistant to inject 0.5-2 mL of local anaesthetic to hydrodissect the space – you should see fascia iliaca momentarily ‘lift’ off the needle tip. If you see muscle tissue expanding, withdraw slightly until just under the fascia
13. Inject under direct vision the calculated dose and dilution of local anaesthetic

Tips:

• The pressure required to penetrate the skin is higher than that required to penetrate fascial planes, so care must be taken not to pass through fascial planes as well when entering the skin
• Holding the skin taught and inserting the needle at a 45-degree angle can help prevent accidental deep penetration
• If unsure, bring the needle tip back to just below the skin surface before advancing again, feeling for fascial ‘pops’
• The volume of anaesthetic needs to be injected completely underneath, but as close to the underside of the fascia iliaca as possible, to remain within the fascial compartment but not intramuscular
• It is good practice to aspirate after every few millilitres infiltrated, checking for blood to ensure no intravascular injection

Ultrasound-guided out-of-plane technique

1. Prime the needle and minimum volume extension tubing with the local anaesthetic, making sure there is no air in the needle tip
2. Hold the transducer with non-dominant hand and the needle with dominant hand
3. Find the ASIS and the pubic tubercle and place the transducer over the inguinal ligament, with the lateral end of the transducer lying on the ASIS. The probe marker should be pointing to the patient’s right
4. Slide the probe towards the pubic tubercle and identify the key structures:
   
   • iliopsoas (iliacus and psoas major)
   • neurovascular structures (lateral to medial)
     1. femoral nerveÌý
     2. femoral artery
     3. femoral vein
        
        
        
5. Once the key structures have been identified, slide the transducer back towards the ASIS until the femoral vessels are only just in view at the edge of the screen
   
   
6. Sweep the transducer 1-3 cm caudally, moving it distal/caudal from the inguinal ligament, keeping the femoral vessels visible at the side of the screen
7. Distal to the ASIS, sartorius becomes visible on-screen and should not be mistaken for iliopsoas
8. If using local anaesthetic for the skin, inject 1-2 mL at the centre marker of the transducer on the distal side, and wait for effect
9. Insert the needle under the centre marker of the transducer on the distal side, aiming under the transducer and watch as the needle tip comes into view under the transducer
10. Reposition the needle until the tip is visible just under the fascia iliaca (the ‘pops’ should be seen and felt as the needle passes through fascia lata and then fascia iliaca)
11. Keep the needle within a few mL of the fascia iliaca
12. Maintain direct vision of the needle tip and ask an assistant to inject 0.5-2 mL of local anaesthetic to hydrodissect the space – fascia iliaca will be seen to momentarily ‘lift’ off the needle tip. If muscle tissue is seen expanding, withdraw slightly until just under the fascia
13. Inject under direct vision the calculated dose and dilution of local anaesthetic
    
    
    

Tips:

• If unsure whether a muscle is iliopsoas or sartorius, follow it back to the ASIS where sartorius inserts and therefore disappears from view
• The pressure required to penetrate the skin is higher than that required to penetrate fascial planes, so care must be taken not to pass through fascial planes as well when entering the skin
• Holding the skin taught and inserting the needle at a 45-degree angle can help prevent accidental deep penetration
• If unsure, bring the needle tip back to just below the skin surface before advancing again, feeling for fascial ‘pops’
• The volume of anaesthetic needs to be injected completely underneath, but as close to the underside of the fascia iliaca as possible, to remain within the fascial compartment but not intramuscular
• It is good practice to aspirate after every few millilitres infiltrated, checking for blood to ensure no intravascular injection

Post-procedure care

• Simple dressing/band-aid for injection site
• Review of injection site for formation of pseudoaneurysm, usually within 2 hours of procedure
• Continue monitoring according to local protocols, mindful of the potential for both delayed local anaesthetic toxicity and oversedation with pre-administered analgesia as the block takes effect and the painful stimulus is removed

Alternatives in case of block failure

• The advised doses can be safely repeated once without reaching toxic levels
• May require ongoing opiate analgesia
• Traction of lower limb provides some analgesia
• Consider discussion with anaesthetics/local pain service

Consider transfer when

• If staff unable to safely perform the procedure
• Uncontrollable pain
• Fracture requiring surgical treatment not able to be performed at presenting hospital
• Signs of local anaesthetic poisoning – discuss with Poisons/toxicology

For 24 hour advice, contact the Poisons Information Centre 13 11 26

For emergency advice and paediatric or neonatal ICU transfers, seeÌýRetrieval ServicesÌý

Parent information

Last updated June 2024