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Research consistently shows that children receive less analgesia for similar conditions than adults. Remember: children cannot verbalise their pain like adults – if you think it would hurt an older patient (or you!) it will hurt a baby. Anaesthetic and analgesic agents can be used safely in children and infants.
Local anaesthetic should be used wherever possible for painful procedures such as venepuncture, cannula insertion, lumbar puncture and laceration repair.
It has been traditional to use local anaesthesia (LA) much less frequently for lumbar puncture than venepuncture – this is illogical.
Infiltration of lignocaine is painful but there are simple ways to diminish this (see below).
Always consider tissue adhesive / steristrips as an alternative to suturing for simple lacerations.
All local anaesthetics (including topical preparations) can cause serious toxicity – know the safe maximum doses for any preparations you prescribe.
Topical Anaesthetics é
These can provide effective anaesthesia for venepuncture and cannula insertion, and reduce the pain of lumbar puncture/bladder aspiration.
Apply to intact skin under an occlusive plastic film dressing (e.g Opsite/Tegaderm).
Ametop probably provides superior pain reduction for IV insertion compared with EMLA, but IV insertion success rate is equivalent.
Emulsified eutectic mixture of 2.5% lignocaine and 2.5% prilocaine. Leave in place for 90 minutes prior to the procedure. Provides anaesthesia down to 3-5mm tissue depth and for up to 2 hours.
Methaemaglobinaemia is a rare life threatening complication of EMLA use (haem Fe2+ is oxidised to Fe3+) caused principally by excess prilocaine absorption. Hence application to areas where absorption will be more rapid e.g. broken skin (burns, lacerations), mucous membranes or diseased skin (eczema/dermatitis) should be avoided. The thinner skin of infants can also result in higher absorption – note safe age and dose recommendations. EMLA can be applied safely to small, superficial lacerations to aid cleaning / gluing.
Recommended maximum daily doses of EMLA1 (1 tube = 5 grams).
EMLA can cause local oedema or vasoconstriction making the procedure harder, removing dressing 10 minutes prior will allow this to resolve.
Suitable for use above 1 month of age.
Leave on for 30 to 45 minutes. Anaesthesia will last for up to 4 hours after removal.
Often causes erythema but this does not necessitate removal or indicate allergy.
Good idea to apply the cream at two sites in case the first attempt at venous access fails (!) and on the back if an LP is likely to be performed.
Available in CED as “Topicaine” - liquid preparation of 4% lignocaine, 0.5% amethocaine and 0.18% adrenaline.
Used as a topical local anaesthetic specifically for application to open wounds or mucous membranes.
Can allow cleaning of wounds that don’t require suturing, suturing of small wounds without injected LA or to reduce the discomfort of injected LA in larger wounds. It can be used in any age of child.
Prior to application warm the ALA to room temperature to reduce stinging (warn patient that it can sting) and gently irrigate the wound to remove excess clot so the ALA is able to contact the wound edges.
Soak a cotton-wool ball and place in the wound if there is a cavity or on the wound if not. Cover with an occlusive plastic film dressing (e.g. Opsite/Tegaderm) and leave for 20 minutes prior to the procedure. Blanching of the area will confirm adequate effect.
Maximum dose is 0.1ml/kg (hence impractical for wounds larger than ~ 5cm).
Contraindicated on distal extremities (e.g. finger, toe) as with all adrenaline containing anaesthetics.
As with EMLA systemic absorption can occur (see lignocaine side effects below) so prolonged or repeated applications should be avoided.
Infiltration of Lignocaine é
Local infiltration is more appropriate when the procedure involves deeper or larger cuts, topical anaesthesia has had only a partial effect or it is not possible to wait before performing the procedure.
Lignocaine without adrenaline is the standard agent and is available in 0.5% and 1% strengths. Bupivicaine 0.5% is used in special situations where a prolonged action is desired (e.g. nerve blocks: see below) but must be used with care as it is markedly cardiotoxic compared with lignocaine.
Use of adrenaline
The addition of adrenaline to local anaesthetic has two useful effects:
Increases the duration of effect by 50 – 100%
Helps provide haemostasis
It is contraindicated for perivascular infiltration at peripheral end arteries e.g. fingers, toes, ears, nose, penis, wrist or ankle.
It should be viewed as something to add when required, rather than omit when contraindicated
The pain of local infiltration is greatly diminished by:
Onset of local anaesthesia after local infiltration or for block of small nerves (e.g. digital n.) is rapid, however it is best to wait 3-5 minutes before starting the procedure for full effect. Reliable duration of action is 30-40 minutes for plain lignocaine, and 2-3 hours for bupivicaine. For large nerves (e.g. femoral n.) time to maximal effect is slower (5-10 mins for lignocaine, 10-15 for bupivicaine) and duration longer (1-2 hours for lignocaine, 4-6 hours for bupivicaine)
It is important to be aware of the maximum safe dose of local anaesthetics, since it is possible to exceed this in small children with local infiltration. It is equally important to avoid direct injection into blood vessels (aspirate before and during infiltration).
*Maximum safe dose can be increased by 50% when used with adrenaline
Signs of local anaesthetic toxicity
Local anaesthetics are neurotoxic and cardiotoxic.
Early symptoms: Perioral tingling, perioral/tongue numbness, tinnitus, agitation/anxiety, dizziness, flushing
Progresses to: Muscle twitches, nystagmus, hypertonia, seizures, CNS depression, coma, bradycardia, hypotension, widened QRS preceding arrhythmias (VT with bupivicaine)
Nerve Blocks in Children's Emergency Dept é
Local anaesthetic blocks are a valuable part of the procedural repertoire for pain relief and wound management. The use of these simple and effective techniques in CED is encouraged, however unless you are familiar with the process guidance of senior staff should be sought.
These techniques can be used independently or, in younger children, in conjunction with sedation allowing lighter sedation.
Advantages over local infiltration
General practical issues
Digital Nerve Blocks
This is a very safe and simple technique. It is the 1st line analgesic for all painful finger or toe injuries/procedures.
Technique: Use the smallest needle that will reach the palmar subcutaneous tissue from the dorsal side of the finger.
Approach from the dorsum (back) of the hand as close to the MCP joint (knuckle) as possible. Inject as you slowly pass the needle down BOTH sides of the proximal phalanx (2 injections only required).
The volume injected should produce obvious swelling, which will rapidly dissipate with gentle massage. ~ 0.05 mls/kg (max 2mls) each side of 1% lignocaine or 0.5% bupivicaine.
Note: big toes (and to a lesser extent thumbs) may require a complete ring block, with additional infiltration along dorsal and palmar/plantar surface of proximal phalanx.
Femoral Nerve Blocks
Supplies femur, anterior and medial thigh and majority of knee joint.
Indicated as 1st line analgesia for femoral shaft fractures. Often useful for fractures of femoral neck and condyles.
The femoral nerve emerges beneath the inguinal ligament lateral to the femoral artery. It lies in a pyramidal shaped potential space which has 2 implications: 1) the nerve does not need to be closely approximated as the LA can spread widely 2) a major reason for failure is inadequate volume injected as dissipation is too wide. With a good volume the obturator and lateral cutaneous nerve of the thigh are also often involved giving effective analgesia to the hip and knee (3-in-1 block).
Technique: Establish IV access and cardiac monitoring. Monitor for 30mins post injection.
Use a 2.5cm 25G needle with a 10 or 20 ml syringe. The nerve lies 1-2 cm lateral to the femoral pulse depending on size. Mentally note landmarks.
Starting just lateral to where the nerve lies enter the skin at ~25o from perpendicular and aim as if toward the umbilicus. Inject and aspirate slowly as you advance.
2 distinct ‘pops’ should be felt, first the fascia lata then the iliopectineal fascia. After the second ‘pop’ there should be a loss of resistance to injection. Fix the needle at this point and inject the entire volume aspirating every few mls. If there is resistance or swelling the needle is likely to superficial. Stop injecting and advance as before.
0.5% bupivicaine is preferred for its long duration of action. Dilution may be required to make an adequate volume. Aim to inject a volume of 0.4 mls/kg (max 25mls) for one femoral nerve block.
Particularly useful for exploration and repair of palm lacerations.
Anatomical variations - block both nerves when lesion is near territory boundaries.
Standard Equipment: 25G or 26G needle with 3-5 ml syringe. Aim to infiltrate ~0.05mls/kg (max 2.5mls) for median and ulnar blocks and ~0.1ml/kg (max 5mls) for radial.
Identify flexor carpii radialis (flex wrist against resistance) and palmaris longus (clench fist). Inject between these two, approximately 1-2 cm proximal to main wrist crease and advancing needle perpendicularly. Nerve is superficial, maximum of 0.5-1 cm deep depending on patient size.
The tendon of flexor carpii ulnaris can be easily felt on a gently flexed wrist. The ‘lateral‘ approach is easiest, starting 1-2 cm proximal to the main wrist crease advance the needle under the tendon aiming to infiltrate just medial to the ulnar artery pulse.
The radial nerve is branching and superficial at the level of the wrist. Using the base of the anatomical snuff box as a landmark fan 2 bands of subcutaneous LA such that they cover the lateral side of the wrist at the level of the main wrist crease. Massage to diffuse the LA helps success.
Excellent for exploration and repair of sole lacerations.
The sural nerve supplies a variable part of the heel and lateral border of the sole, the tibial nerve the rest. Three other nerves supply the dorsum of the foot.
The landmark is the midpoint between the most prominent point of the medial malleolus and the Achilles tendon. The tibial artery pulse may be felt and the nerve wraps around this. Advance the needle such that it feels it would just slide behind the tibia ~0.5-2 cm depending on patient size. If you hit bone you are to anterior or too deep.
Infiltrate ~0.1mls/kg (max 5mls) of LA and massage. Entering the artery is not a disaster, simply withdraw until negative aspiration then infiltrate as above.
Superficial subcutaneous nerve running between the lateral malleolus and Achilles tendon. Fanning ~0.05-0.1 mls/kg (max 5mls) of LA subcutaneously between these points should catch it.
Facial Nerve Blocks
Vital for accurate repairs of the vermillion border of the lip.
In younger children used in conjunction with sedative agent. Blocking nerves bilaterally is necessary for central lacerations.
Standard technique is ~0.05 mls/kg (max 2.5mls) 1% lignocaine using 25G needle and 3 ml syringe for both.
Supplies medial cheek and upper lip. Does not cover gums, teeth or nose. Exits through the infraorbital foramen. This is a large foramen that can be located medial to the zygomatic arch in a line between the pupil and upper canine. It is most easily accessed from the intraoral route. One hand lifts lip then insert needle at reflection of the oral mucosa above canine. Advance ~0.5-1cm towards foramen, do not attempt to enter foramen as retrograde spread of LA can produce very extensive facial blocks. Infiltrate gently and massage as with usual technique.
Supplies chin and lower lip (not gums or teeth). Exits mandible through the mental foramen, a small foramen located in the middle of the mandible just posterior to the lower canine. The intraoral route is again easier. Evert the lip, insert the needle ~0.5-1cm at the reflection of the oral mucosa just posterior to the canine. Inject gently and massage.
Lander JA, Weltman BJ, So SS EMLA and amethocaine for reduction of children's pain associated with needle insertion. Cochrane Database Syst Rev 2006.:CD004236
Lillieorg S, Otterman I et al. Topical anaesthesia in neonates, infants and children. Br J Anaesth 2004; 92: 450-451
Taddio A, Ohlsson A et al. A systematic review of lidocaine-prilocaine cream (EMLA) in the treatment of pain in neonates. Pediatrics 1998; 101: E1-E9
Brisman M, Ljung B et al. Methaemaglobin formation after the use of EMLA cream in neonates. Acta Paediatr 1998; 87: 1191-1194
Simpson S. Regional nerve blocks Part 3 – Regional nerve blocks of the hand. Aust Fam Phys 2001; 30: 669-671
Simpson S. Regional nerve blocks Part 4 – Regional nerve blocks of the foot and ankle. Aust Fam Phys 2001; 30: 771-773
Simpson S. Regional nerve blocks Part 6 – Femoral nerve blocks. Aust Fam Phys 2001; 30: 970-972
Jankovic D, Wells C. Regional nerve blocks, 2nd edn. Blackwell Science 2000; Ch 3
The excellent anatomical diagrams are from the series of articles by Dr Scott Simpson published in Australian Family Physician referenced above (used with permission of the author).