ENSURING THE SUCCESS OF REGIONAL BLOCKS

Dr P Narasimha Reddy, MD,DA

Professor & HODDept of Anesthesiology & Critical Care

NRI Medical College & General HospitalChinakakani, Guntur Dist, A.P.

Introduction

Regional anesthesia was popular

Tragic incident in Britain.

It was an art

Now it is a scientific and business like

Answerable to patient’s problems

Continuous search to improve safety and surety

Inventions like PNS and imaging techniques

History

1884- Karl Koller –cocaine

1889- Karl Ludwig- infiltration

1884-William Halstead-LA directly into nerves

1885-L.Corning-accidental-epidural

1898-August Bier-spinal anesthesia

1912-Kulen Kampff-supra.cl.block on himself

1912-Von Perthes-PNS

1944-AP Winni-perivascular technique

1978-La-Grange-doppler u/s to locate nerves

1992-Fried &Fritz- axillary block with u/s

Regional Blocks - Advantages

Simple Economical Complete analgesia Reduced stress response Good relaxation Less blood loss Less blood transfusions

Contd…

Good operating field

Conscious patient

Less action on immune system

Post –op analgesia

Minimal stay in hospital

Less incidence of DVT

Early bowel recovery

Early ambulation

Disadvantages

Failures

Neurological problems

Anxious patients

Action on free radicals – more

Anatomy

Pharmacology

Complications and side effects

Technique of blocks

Pre-requisites

Select your patientPatient – Exclude- Over anxious Needle phobia Anti psychotic therapy Language barrier Morbid obesity Severe arthritis Degenerative nerve disorders & Adolescent group

Success depends on your patient

Select Your Surgeon

Good sympathetic, understanding

Delicate hands and movements

No pulling

No pressure on the patient &

Not much of retraction

Select Your Block

Logical selection

Depends on site, duration & speed of surgeon

Eg., ISB for shoulder surgeries

AXB for fore arm and hand surgery

Missing nerves can be blocked separately

Select Your Drug

Depending on duration of surgery

Post – op analgesia

Use enantiomers than racemic mixtures

Use less toxic drugs

Ropivacaine is more sensory blocker

Bupivacaine not used in Biers block

Contd…

Adjuvants :

Sedatives –

Titration

Verbal contact

No drug prevents toxicity of LA

Vaso constrictors –

Epinephrine 1 in 2-2.5 lakhs

Freshly prepared solution

Prolongs block

Reduced toxicity

Used as a marker

Use full also with Bupivacaine

Contd…

Soda - bicarb –

1 ml for 10 ml of Xylocaine

0.1ml for 10ml of Bupivacaine

Hyaluronidase –

Used in ophthalmic practice & field blocks

Contd…

Additives :

Many drugs are being added to local anaesthetics –

Tramadol

Buprenorphine

Clonidine

Neostigmine

Contd…

Ketamine

Fentanyl

Epinethrine

They prolong the block, prevent patchy Analgesia, depth of block quick onset of

sensory & motor block

Contd…

Select Your Equipment

Glass syringes are better than disposable

Short bevelled needles are better

Disposable kits are more useful

Select Your Technique

By facial clicks :

Nerves will be in fascial sheath

Anesthetist must feel the click when he enters the sheath

Well appreciated with short bevel needles

Success rate is 60-65%

By Paresthesias :

Moore said “no paresthesia – No anesthesia”

It is an abnormal sensation

It indicates needle tip near the nerve or nerve injury

Exaggerated paresthesias are undesirable & dangerous

Success rate is 70-90%

Contd…

By Trans arterial injection :

Good indication that needle is in the sheath

Stan et al – safe with minimal complications & high success rate

Complications :

- Intra arterial injection

- Haematoma

- Needle can be deep into muscles

Contd…

By peri-vascular injection : Suggested by Winni Ronie & Thomson opposed Patridge, Katz and Bernischke

demonstrated septae but they are thin Anatomical land marks are very

important All these techniques depend on normal

anatomy, but there are many anatomical variations

Skill & experience of anaesthesist will not work here

Success rate is 60-65%

Contd…

Anatomical variations :

Tuffiers line crosses between L3-L4 or L5-S1

Termination of cord

Root size

Volume of CSF

7 major configurations of B plexus

61% defer from right to left

Contd…

Peripheral Nerve Stimulator :

It is better than blind injection

Popularized by Dr. P. Raj

Success Rate 93%

Contd…

Advantages :

Less latency

Less nerve injury

Less quantity of LA

Getting motor response with less than 0.5 mA

Contd…

Pitfalls of PNS :

Correct polarity of the stimulating needle

Positive electrode – secured to the patient

Loose connections and flat batteries must be avoided

Motor response must be in the distal group of muscles

Contd…

Disadvantages :

Nerve stimulator settings have no consisting relationship to the proximity of the nerve

Neuropathies, diabetes, toxic neuropathy, chemotherapy, radiation, demyelinating disorders, multiple sclerosis, peripheral vascular disease, old age can mute the response

Contd…

Amputees

Difficult to locate the nerves

Nerve damage can occur

Parasthesias after the block

Compartmental syndrome

Contd…

Single Vs Multiple injections :

It is not clear weather single Vs multiple stimulation & injection are superior to single injection

AXB – 2, 3, 4 injections have high success rate

Neuroproxia is 1-7%

Contd…

Continuous Catheter Technique :

Very exciting & developing area

Nerve is located with PNS using conductive needles

Catheter is passed 2 to 3 cm beyond the needle

STIMUCATH are used to locate the nerves & to find epidural space

This technique is used in particular places

Contd…

Percutaneous Electrical Guidance (PEG):

New technique developed by W.Urmey

Noninvasive

Indentation of skin with cylindrical smooth tipped probe

The needle is passed through the channel in the probe

GROSSI proposed a new concept of anesthetic line

Contd…

Imaging Technology

In 1978 Doppler U/s was used to locate the nerves

Fluoroscopy & U/s was used to locate the vessels

Software is available to image the nerves

Modern machines are affordable, portable with better resolution and penetration

Advantages :

Direct visualization of nerves

Direct visualization of other structures

Direct & indirect visualization of LA spread

Re-position of needle in case of misdistribution of LA

Avoidance of side effect

Contd…

Avoidance of painful muscle contractions due to PNS

Faster onset

Longer duration of blocks

Improved quality

Blocks under GA

Neuropathies & Amputees

Contd…

Ultrasound scanned image obtained in the infragluteal fossa midway between the greater trochanter and ischial tuberosity with the probe oriented along the long axis of the sciatic nerve. The sciatic nerve is

seen as a long tubular structure located deep to the muscles

Ultrasound scanned image of the femoral nerve surrounded byHypoechoic (dark) local anesthetic (L) creating a “doughnut” sign

Basic Views :

Nerves can be imaged in short or long axis

Short Axis (SAX) – when probe is aligned perpendicular to the axis of the nerve, the nerve is seen in cross section

Long Axis (LAX) – when probe is aligned parallel to the axis of the nerve

Short Axis View is preferred due to easy identification of nerves, more stable view & allows to visualise circumferential spread of LA. This is called “Doughnut” sign

Contd…

Schematic representation of the views and needle approaches for nerve blocks with ultrasound imaging. A. Short axis view of a nerve with an out-of-plane needle approach. B. Short axis view of a nerve with an in-plane needle approach. C. Long axis view of a nerve with an out-of-plane needle approach. D. Long axis view of a nerve with

an in-plane needle approach. Modified6.

Needle Approaches :

In plane (IP) – long axis of the needle is oriented to the long axis of the probe

Entire needle can be seen

Out of plane (OOP) – the long axis of the needle is the oriented perpendicular to long axis of the probe

Only part of the needle is seen

Contd…

Successful imaging of nerves :

Use lot of gel

Adjust gain, frequency and focus on U/s machine so that muscles appear fairly dim and nerves will be denser

Nerves run along the borders of other structures i.e., muscles

When scanning transversely slide change in angle of U/s probe along any axis results in better quality image

Contd…

Interscalene groove trunks appear hallow like vessels without flow. But they appear mottled when followed peripherally

U/s cross section of nerve looks like a bundle of straws viewed end on

Follow a survey pattern using land marks are border of tissues

Using orientation on the screen

Contd…

Many potential targets on screen move with U/s probe back and forth and get oriented to tissues i.e., nerves

Tendons & ligaments can move with nerves – when move the limb

Vessels - color Doppler, press

Repeated views of nerves on U/s machine

Contd…

Equipment :

U/s machine (high resolution U/s) with compound imaging multi-frequency linear array probes and recording capabilities

22G insulated needles are various lengths – 2” to 6”

High frequency and high resolution – low penetration 10-14 MHz

Broadband transducers 5-12, 8-14 MHz offers excellent resolution

Contd…

Linear array transducers parallel sound beam HRUS software

Peripheral nerves – Hypo or hyper echoic, depending on size, sonographic frequency & angle of U/s bean

Longitudinal view – relatively hyper echoic band, multiple discontinuous, hypo echoic stripes separated by hyper echoic continuous lines

Contd…

Failures in U/s :

Injection of LA into adjacent compartments

Injection can enter the muscles

Contd…

Avoiding failures :

Your attention must be on the target on the screen

Never inject all the drug at a time

Reposition the needle at least twice or thrice during the injection

Contd…

Picture showing the orientation of the ultrasound probe and the needle for placement of an interscalene block with

the in-plane needle approach

Ultrasound scanned image in the interscalene region showing a cross-sectional view of the brachial plexus

located between the anterior scalene (ASM) and middle scalene muscles (MSM), underneath the lateral border of

the sternocleidomastoid (SCM) muscle. The internal jugular vein (IJ) lies deep to the SCM muscle

Ultrasound scanned image of the brachial plexus in the supraclavicular region showing the subclavian artery (A) in its cross-section. The nerve structures of the brachial

plexus are located superolateral to the artery.

Ultrasound scanned image of the brachial plexus in the axiallary region showing a cross-sectional view of axiallry artery (A) and vein (V). The

nerves are located around the artery, with the ulnar nerve medial, between the artery and the vein, radial nerve posterior & median nerve adjacent & superficial to the artery. Also seen is the musculocutaneous

nerve between the coracobrachialis & biceps muscles

Ultrasound scanned image in the popliteal fossa approximately 7 cm proximal to the popliteal crease showing a cross-sectional view of the popliteal (sciatic) nerve. The nerve lies superficial

and lateral to the popliteal artery and vein

• Should anesthetist use ultrasound guided nerve blocks?

• What about training?

- Learning curve

- first with PNS and later ultra sounding of the nerve ( dream ticket) afterwards directly with ultrasound.

Conclusion

Not as a first case

Centralize your equipment

Select proper block

Good knowledge of anatomy

No about potential complications on treatment

Select right patient

Pick the right surgeon

Be confident about your block

But still if you fail

Failures are the stepping stones for success

Contd…

• What about the future of regional anesthesia?