Ensuring the success of regional blocks
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Transcript of Ensuring the success of regional blocks
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?