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Peripheral Nerve BlocksPeripheral Nerve Blocks

Useful in the ED.Useful in the ED. AdaptedAdapted fromfrom

source.source.

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ObjectivesObjectives

Why should we do them ?Why should we do them ?

How effective are they ?How effective are they ?

What are the limitations ?What are the limitations ?

What drugs are available ?What drugs are available ?

What are the risks ?What are the risks ?

The technique behind theThe technique behind the femoralfemoral,, ankleankle

and aand a wristwrist blocksblocks

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Peripheral nerve blocksPeripheral nerve blocks

are excellent for providing prolongedare excellent for providing prolongedanaesthesia and analgesiaanaesthesia and analgesia

are generally safe and easy to performare generally safe and easy to perform

require very little equipment or set up timerequire very little equipment or set up time

allow for minor procedures to be done outside ofallow for minor procedures to be done outside oftheatre without the need for general anaesthesiatheatre without the need for general anaesthesia

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Block dynamicsBlock dynamics

Speed + duration depends on the local anaesthetic used,Speed + duration depends on the local anaesthetic used,

the volume and concentration,the volume and concentration,

and whether any adjuncts usedand whether any adjuncts used

loss of sensation develops faster than motor blockadeloss of sensation develops faster than motor blockade

Onset ofOnset ofactionaction

Duration ofDuration ofanaesthesiaanaesthesia

Duration ofDuration ofanalgesiaanalgesia

Bupivacaine 0.5%Bupivacaine 0.5%

(Marcain(Marcain))1515--30 mins30 mins 55--15 hours15 hours 66--30 hours30 hours

Lignocaine 1.0%Lignocaine 1.0% 1010--20 mins20 mins 22--5 hours5 hours 33--8 hours8 hours

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LimitationsLimitations

AgeAge

Patient refusalPatient refusal

Allergy to local anaestheticAllergy to local anaesthetic

Superficial infectionSuperficial infection

Previous neurological deficitPrevious neurological deficit

Risk of compartment syndromeRisk of compartment syndrome

Ankle blocks in particular are painful and mayAnkle blocks in particular are painful and mayneed some iv sedation +/need some iv sedation +/-- short acting opiate analgesiashort acting opiate analgesia

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What drugs to use ?What drugs to use ?

Lignocaine 1% and marcainLignocaine 1% and marcain 0.5% plain are available0.5% plain are available

In theatres other drugs are used that are less cardiotoxicIn theatres other drugs are used that are less cardiotoxic

and adrenalin is often added to increase duration andand adrenalin is often added to increase duration and

speed of onsetspeed of onset

Bicarbonate can also increase speed of onset andBicarbonate can also increase speed of onset andtheoretically reduce pain of injectiontheoretically reduce pain of injection

Sometimes other drugs are added in the theatre settingSometimes other drugs are added in the theatre setting

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Avoiding toxicityAvoiding toxicity

MarcainMarcain is safe at dosage below 1 mg/kg plainis safe at dosage below 1 mg/kg plain

(1.5 mg/kg with adrenalin)(1.5 mg/kg with adrenalin)

MarcainMarcain 0.25% in 20mls = 50mg0.25% in 20mls = 50mg

MarcainMarcain

0.5% in 20mls = 100mg0.5% in 20mls = 100mg

This only important when large volumes injectedThis only important when large volumes injected

ie : femoral nerve blocksie : femoral nerve blocks

Lignocaine is safe at dosage below 3 mg/kg plainLignocaine is safe at dosage below 3 mg/kg plain

(5(5--7 mg/kg with adrenalin)7 mg/kg with adrenalin)

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Complications ?Complications ?

Related to drug and to injectionRelated to drug and to injection

HaematomaHaematoma -- ( minimum needle insertions )( minimum needle insertions )

InfectionInfection -- ( rare with aseptic technique )( rare with aseptic technique )

Nerve injuryNerve injury -- ( paraesthesia )( paraesthesia )

ToxicityToxicity -- ( aspiration / vigilance )( aspiration / vigilance )

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Nerve injuryNerve injury

Some debate over significance of elicitingSome debate over significance of elicitingparaesthesiaparaesthesia

Nerve injury is reduced by listening to the patientNerve injury is reduced by listening to the patient

andand notnot injecting if resistance encounteredinjecting if resistance encountered

Most accidental nerve block neuropathies resolveMost accidental nerve block neuropathies resolve

over time and patients need to warned about this possibleover time and patients need to warned about this possiblecomplicationcomplication

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Femoral Nerve BlockFemoral Nerve Block

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Ankle blockAnkle block

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Cutaneous innervationCutaneous innervation

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PreparationPreparation

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Deep peroneal blockDeep peroneal block

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Wrist blockWrist block

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Radial Nerve BlockRadial Nerve Block

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Median Nerve BlockMedian Nerve Block

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Ulnar nerve BlockUlnar nerve Block

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Any questions ?Any questions ?