brachial plexus block new

P.N.REDDY-HYCOME 2004

BRACHIAL PLEXUS BLOCKA REVIEW

Dr.P.NARASIMHA REDDY M.D D.APROFESSOR & H.O.DDEPT. OF ANAESTHESIOLOGYKURNOOL MEDICAL COLLEGEKURNOOL


Brachial plexus- a review

• 1)Introduction • 2)Brief history• 3)Applied anatomy• 4)Approaches to brachial plexus• 5)Techniques of brachial plexus block• 6)Some relevant facts• 7)Complications• 8)Future research


Introduction• The word plexus means to twine. It implies a

network of nerves or vessels.• “Man uses his arms and hands constantly.. As a result he exposes his arms and hands to

injury constantly.. Man also eats constantly… Man’s stomach is never really empty.. The combination of man’s prehensibility and

his unflagging appetite keeps a steady flow of patients with injured hands and full stomachs streaming into hospital emergency rooms.

DAVID LITTLE 1963.


Introduction

• To give a successful block One must have

1) Perfect anatomical knowledge of nerves and dermatomal distribution.

2) Perfect knowledge about local anaesthetic agents, complications and side effects.

3) Perfect technical skill which is gained by experience.


HISTORY

• 1884 – Karl koller used cocaine in clinical practice.• 1859 – 1922 – Karl ludwig used infiltration

anaesthesia.• 1884 – Halstead

Matas

Crile injected local anaesthetic directly into the nerves.

- Hirschel injected brachial plexus blindly.• 1912 – Kulen Kampff after experimenting on

himself used supraclavicular technique.


History

• 1922 – Gaston Labott used axillary block.

• 1940 – MacIntosh and Mushin modified Kulen Kampff block and wrote a monogram on supraclavicular block.

• 1964 – Alon P Winnie described pervascular sheath and block.


APPLIED ANATOMY

• Except for cutaneous supply to upper medial aspect of the arm and uppermost aspect of shoulder entire supply to the arm is by brachial plexus.

• Anterior primary divisions(or roots) of C5-8 to T1(C4- prefixed, T2 – postfixed).

• Roots unite to form three trunks.• Trunks converge on to the first rib and divide into

anterior and posterior divisions.• These divisions unite in the axilla to form cords.• The plexus gives rise to 21 nerves, 9 above the

clavicle.


Applied Anatomy Name peripheral S.branches Axillary upper lat. Cut. N. of arm lower lat. cut. N. of arm Radial post. Cut N. of arm

Post. Cut. N. of forearm Cut. To dorsum of hand

Ulnar Cut. To dorsum of hand and palm

Median Cut. To dorsum of hand and palm

Musculo cut. Nerve Lat. Cut. N. of forearm Medial cutaneous nerve of arm and forearm araise directly from

medial cord. with interscalene approach c8 and t1 are likely to be missed

and in axillary block musc. Cut. And radial nerves are likely to be missed.

In such situations brachial block with selective nerve blocks will give good results and prolonged post operative pain relief.


Applied Anatomy

Rule of 3 and 5 roots 5 C5-TI

Trunks 3 superior(C5-C6) Middle (C7) Inferior (C8-T1)DIVISONS 3 Anterior

3 PosteriorCords 3 Lateral medial

posteriorTerminal nerves 5 Median(lat and med. Cords) Musculo c.N. (Lat. Cord) ulnar (Med. Cord)

Axillary (Post. Cord) Radial(Post. Cord)


Applied Anatomy

• Peripheral nerves:

Both sensory and motor supply of upper limb from infraclavicular part of B.P.

Because of interconnection of 5 nerve roots there is overlapping and difference between dermatomal, myotomal and sclerotomal distribution of individual nerves.

Seven major configurations of B.P are noted.in 61% there is left to right asymmetry.


Applied Anatomy

• Relationships:

vertebral A. travels cephalaud and enters bony canal ar C6.

Cervical roots are just post. To vertebral A.

Ext. Jugular vein overlies the interscalene groove at C6.

Over the first rib the divisions of B.P lie post., cephalaud and lat. To subclavain A.

Axillary A. lies ant. To radial N., Postero medial to median nerve, Posterolateral to ulnar N.


Applied Anatomy

Non brachial plexus anatomy: 1) supraclavicular nerve (c3-4) provides

sensory supply to ‘cape area’ 2)suprascapular nerves (C5-6) sensory

fibers to the posterior aspect of the shoulder capsule, acro. Cla. Jt., cut. Supply to proximal third of arm in the axilla.

3) Intercostobrachial nerve (T2) with medial cut. N. innervates upper half of the post. And medial side of skin of the arm.


Applied Anatomy

Sensory innervation of the arm: It is to determine

which cut. N. distribution is with in the surgical field,

which terminal nerves require supplementation in partial block and

Determine pre and post operative neurological deficits.


Applied Anatomy

Motor innervation of the arm: It is important when we are using PNS to elicit end point.

Sup. Trunk stimulation at ISC groove- shoulder elevation.

Median nerve stimulation – forearm pronation, wrist flexion and thumb opposition.

Ulnar nerve stimulation – ulnar deviation of wrist, finger flexion and thumb adduction.

Radial nerve stimulation – extension of wrist and fingers.

Assessment of efficiency of block can be done by evaluating the function of each individual nerve.


Applied Anatomy

• Rule of 4 P’s:1) Patient is asked to push the arm by

extending the forearm at the elbow (radial nerve).

2) To pull the forearm at the elbow(Musc. Cut.N.).

3) Ability to distinguish a Pinch at the palmar base of index finger (Medain N).

4) Ability to distinguish a pinch at the palmar base of little finger(Ulnar N).

.


Choice of approach

• Depends on

1) site of surgery

2) duration of surgery

3) surgeon

4) anaesthetist

5) Patient.


Approaches to brachial plexus

• Inter scalene block(ISB):

Surgery on the shoulder

can spare C8-T1(ulnar in 50%)

Poor for arm and hand surgery

10-15ml of L.A

Central neuraxial blockade

vagal or phrenic nerve blockade

Pneumothorax rare

Intravascular injection a possibility


INTERSCALENE BLOCK


Approaches- contd.

• Supraclavicular block:

Provides anaesthesia for entire extremity

“No parasthesia- No Anaesthesia” an aphorism by- Dr. Moore is more appropriate

BID success rate is more than 95%

It is modified by Macintosch

Vertical method “Plumb-Bob” method

P.N.REDDY-HYCOME 2004 SUPRACLAVICULAR BLOCK


Approaches contd.

Inter sternocledomastoid block:

For hand and arm surgery

Needle is directed laterally placed in between the two heads of the sterno-mastoid muscle

Catheter insertion is easy and safe

Less risk of pneumothorax

15% failure in ulnar distribution


CONTINOUS INTERSCALENE BLOCK


Approaches contd.

• Infraclavicular block (coracoid approach):

For surgery on arm and hand

More consistent anaesthesia for axillary and MUSC. Cut.N.

Latency more

No changes in pulmonary function

Catheter fixation is easy


INFRACLAVICULAR BLOCK


Approaches contd.

Axillary block(AXB):

• For hand surgery

• All techniques work at terminal branches level

• Success rate 60-100%

• Anaesthesia of MCN is done by a separate injection into the belly of coracobrachialis


AXILLARY BLOCK


Approaches contd.

• Mid humeral block 1994 By Dupre

Each individual nerve is located at the junction of upper one third to the lower two thirds of the humerus in the humeral canal.

Success rate is very high

Latency less

Low volume of L.A.

Time consuming


TECHNIQUES FOR BP BLOCK

Fascial clicks: Mostly we depend on fascial clicksWell appreciated with short beveled needlesMany studies gave mixed results• Paraesthesias:An abnormal sensationIndicate that the needle tip is near the nerveThey also indicate nerve injuryRepeated or exaggerated parasthesias are

undiserable Success rate – 70 to 90%


Techniques Cont…. PNS:

Is popularised by Raj. P in peripheral nerve blocks

Success rates are high

Latency is very less

Nerve injuries are less

Motor response with ≤ 0.5mA gives successful blocks

Pitfalls are: Correct polarity of the needle


Techniques Cont….• PNS Cont… Pitfalls are: Correct polarity of the needle is

important Positive electrode should be secured to

the patient Loose connections and flat batteries to be

avoidedMotor response should be in the distal

group of musclesNerve damage can occurCompartmental syndrome can occur


Techniques Cont..• Transarterial:Penetration of artery is a good indication of

needle in the axillary sheathStan et al. – showed that it is very safe with

minimal complications and high success rateCocking’s – A single injection of large volume.

Success rate – 99%• Perivascular:BP is enveloped by fibrous sheath from cervical

spine to midportion of forearmA.P Winnie suggested large volume of single

injection into the sheath will suffice


TRANSARTERIAL TECHNIQUE

AXILLARY BLOCK


Techniques Cont….

• Perivascular Cont

It was challenged by Thompson. He said each nerve is in separate sheath

Rorie described septae in neurovascular bundle, demonstrated compartmentalization of dye. This explains profound/partial block

Patridge, Katz and Benirschke demonstrated septae but they are very thin and incomplete

Communication exist in between septae

Touch and feel is the main guiding principle


Techniques Cont….

• Imaging techniques:

Fluroscopy and ultrasound

U /s of blood vessels used to assist BP Block

Recently u /s nerves described

This is the future promise for the

Anaesthetists

Drawbacks: 1.Interpretation 2.Size of the probe 3.2/3 dimensional views 4.No functional end point


Techniques Cont…..

• P.E.G (Percutaneous Electrical Guidance):

By W. Urmey. F

This is a new technique

Involves indentation of skin and transcutaneous stimulation with cylindrical smooth tipped electrode probe to locate desired and later to guide a block needle to the nerve

Grossi proposed concept of anaesthetic line.

P.E.G. concept works well with anaesthetic line



• Single versus multiple injections:

Still it is not clear which one superior

AXB using 2,3 and 4 injections reported high success rate

More complete block, less anaesthetic agent and shorter latency

Incidence of neuropraxia is 1.7%

Time consuming



• Continuous techniques:

Exiting and evolving areas of block

Particular approaches are useful

Catheter fixation is difficult

Migration of catheter

Use of large bore needles and prolong searching for nerves

Injection any solution


SOME GUIDING PRINCIPLES FOR BP BLOCK

• SEDATIVE DRUGS:Titration is very importantNo drug absolutely prevents drug toxicityPatient should not be unconcious• LOCAL ANAESTHETIC AGENTS:Higher concentrations not necessaryMixing is not very usefulAlkalnization gives useful resultsRate of convulsions per 1000 blocks:

(A)1.2-epidural (B)1-2.8 axillary (C)7-8 interscelene/supraclavicular


Guiding principles cont…..

• LA Cont……

Drugs Duration

(hrs)

Concentr-- ation (%)

Dose

(mg / kg)

Lidocaine 4-7 0.5-1 7mg with adrenaline

Bupivacaine 8-12 0.25-0.5 2-3

Ropivacaine 8-10 0.25-0.5 2-4


Guiding principles cont….

• Vasoconstrictors:

Epinephrine is the drug. 1:2,00,000 is appropriate

Freshly made solution

• Equipment and needles:

Nondisposable syringes

Sterility

Short bevel needles are best



• Additives:

Many drugs to LA to potentiate and to prolong the block

Ketamine BuprenorphineClonidine Tramadol Neostigmine



• Measuring success of block:

Difficult to measure

Always some legal, political, social, educational and personal reasons to use additive drugs

Not an excuse for sloppy technique or inappropriate dosing


COMPLICATIONS• Incidence: Extremely rare• France study of 21,278 blocks cardiac

arrest – 0.01%

death – 0.005%

seizures – 0.8%

radiculopathy – 0.02%• ARNI(Anaesthesia Related Nerve Injuries)

16% of ASA claims

Out of these 8% ulnar, 20%BP

RA did not increase the risk of neuropathy in patients with preexisting neuropathy


Complications cont…

• Peripheral nerve injuries:

Residual paraesthesia, hypoasthesia and rarely permanent paresis

Early onset indicates extra or intra neural haematoma or injection or edema

Late onset suggests tissue reaction or scar formation


Complications cont….

• Factors contributing to nerve injuries:

Categories Pre op. risk factors

Patient factors Preexisting neurological disorders

Male, old age,extemes of body habitus, DM

Surgical factors Surgical trauma, strech of nerves, tourniquet ischemia, vascular compromise, peri op. imflamation, post op. infection, hematoma, cast compression, pt. position

Anaesthesia factors

Needle or catheter trauma, vasoconstrictors, perineural edema, LA toxicity



• Factors that contribute directly to ARNI include:

1. Mechanical trauma

2. Ischemic injury and

3. Chemical injury


Complications • MECHANICAL TRAUMA:

Needle:

Trauma depends on type of needle and elicitation of parasthesias

Selander et al. examined 24hr histological changes in rabbit sciatic nerve

injury more with long bevel needles(14° vs 45°short bevel)

severity of injury more with short bevel needles

Rice Mc Mahan – observed parallel insertion of needle – less injury than transverse insertion


Complications cont….• Mechanical trauma cont….

Parasthesias:

Whether elicitation of parasthesias cause

direct needle trauma there by increasing the risk of nerve injury is unknown

Selander reported higher incidence of ARNI when parasthesias are sought in AXB with perivascular technique (2.8% vs 0.8%)

Auroy et al. noted cases of radiculopathy associated with parasthesias are pain during injections



• Parasthesias cont…

Winchell and Wolfe reported 0.36% of ARNI despite 98% of patients experiencing parasthesias.

Moore’s contension was mechanical parasthesias during RA are persae not an indication of nerve injury

Pain during injection increases the risk

Supplimental injection after a failed block or under GA increases the risk


• ISCHEMIC INJURYFunctional integrity of nerve depends on its

micro circulationIntrinsic supply of exchange vessels within the

endoneuriniumExtrinsic supply of larger nutritive vessels

which are under control of sympathetic system and responds with epinephrine containing solutions

NBF(Neural Blood Flow): Plain 2% lidocaine reduces NBF by 39%. By adding adrenaline 1:2,00,000 NBF reduced by 78%.

complications


Complication cont….

• Ischemic injury cont…Epinephrine: Adrenaline is safe when added

to nerve bundles in appropriate concentrations with intact barrier mechanisms (blood neural barrier)

Epinephrine may increase the risk with disrupted barrier mechanism or by decreasing the NBF as in intraneural injection or chemotherapy related neurotoxicity, DM neuropathy or atherosclerosis


Complications cont…• Ischemic injury cont…

Neural edema: Can occur after intraneural injection of LA

Intraneural pressure may go upto 100mm of Hg for up to 15min after injection

Increased pressure interferes with microcirculation or alter the permeability of BNB

Results in degeneration and dystrophy of axons. Fibroblasts proliferation causes late changes, increasing perineural thickening and endoneural fibrosis


Complications .

• CHEMICAL INJURY

In clinical concentrations LA are safe to the nerves

Higher concentrations, prolonged exposure and intraneural injection cause damage

Both long acting, short acting with or without adrenaline can cause changes depending on the concentration

Continuous catheters – more incidence of injuries

Most of the time the injury may be single or combined.


Complications cont…• VASCULAR INJURIES: Rare but potentially dangerousIn anticoagulated patients definite guidelines not

available. Benefits must be weighed against the risks

Transient vascular insufficiency: Reported in AXB, may be due to intra-arterial puncture. Incidence 1%

Hematoma: 0.001-0.02%. May or may not be associated with post operative nerve problems

Pseudo-aneurysm and axillary artery dissection is reported



• MUSCLE INJURIES:

Necrosis can occur at the site of injection

More so with bupivacaine

Depends on dose, time of exposure and calcium levels in muscles

Hemidiaphramatic paralysis(HDP):

ISB – 90 to 100%, mild dyspnoea, 25 – 30% reduction in RS function, ropivacaine is not protective, abnormal RS function persists for 24hrs in 50% of patients


Complications

• PNEUMOTHORAX:

Common in SCB

Also occurs in ISB and ISCB

Plumb-bob technique reduces the incidence

Careful with tall, thin and emphysematous patients

Symptoms occur after 6 – 12hrs after injection

Immediate symptoms if patients is on IPPV


Complications • LA REACHING UNINTENDED PLACES:

Intravascular injection: 0.2% in transarterial Can occur in ISB and SCB Direct injection or retrograde flow via subclavian

artery Convulsive dose of bupivacaine is 3.6mg,

lidocaine is 14.4mg Safety margin

bupivacaine:l-bupivacaine/ropivacaine:lidocaine

1 : 2 : 9


Complications

• LA Reaching unintended places cont…Subarachnoid/epidural space: Common in ISB Needle enters directly or via dural cuff Avoided by shorter needles and directing the

needle cauded Slow, fractionated dosesCervical sympathetic chain: Horner’s syndrome – common in ISB, SCB 20 to 90%, no harmRecurrent laryngeal nerve block: Common in ISB and SCB – 1.3%. Hoarseness

of voice. Treatment: Reassurance


Complications

• HYPOTENSIVE / BRADYCARDIAC EVENTS(HBE):

13 – 24% patients develop HBE in shoulder arthroscopy under ISB

Mechanisms could be1. β-agonistic effects of epinephrine or

activation of Bezold-Jarisch reflex HBE is reduced by prophylactic

metaprolol but not glycopyrrolate Metaprolol 2.5mg increments upto 10mg

or to get HR about 60/min


Complications

• TOURNIQUET EFFECTS:Ischemic injury under the compressed area

occurs with in 2-4hrsIn non compressed area occurs at about 6hr40min needed re-establish normal status after

deflationPain of tourniquet by complex mechanism –

neural ischemia transmitted by nonmyelinated C fibres

Pain disappears immediately after deflation


Complications • LIMB PROTECTON AND DISCHARGE

CRITERIA: No RCT data Prolonged blocks can increase the risk of

nerve injury Can be discharged with partial sensory block

with instructions to avoid thermal or pressure injuries

Fitted with a sling or protective device Mid Humeral block is best Blocking the individual nerves with different

agents

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