Clinical Pearl for a Successful and Safe PNS Guided Peripheral Nerve Block

Vol 2 | Issue 2 | July-December 2021 | Page 143-144  | Ritesh Roy, Himjyoti Das, Neha Singh, Surajit Giri, Hetal Vadera, Vrushali Ponde

DOI: 10.13107/ijra.2021.v02i02.044

Authors: Ritesh Roy [1], Himjyoti Das [2], Neha Singh [3], Surajit Giri [4], Hetal Vadera [5], Vrushali Ponde [6]

[1] Department of Anaesthesia and Pain management Care Hospitals, Bhubaneswar, Odisha, India.
[2] Anesthesia and Critical care, Nazareth Hospital, Shillong, Assam, India.
[3] Department of Anesthesiology and Critical care, AIIMS, Bhubaneswar, Odisha, India.
[4] Department of Anesthesia, Pragati Hospital, Sivasagar, Assam, India.
[5] Department of Anaesthesia, Sterling Hospital, Rajkot, Gujarat, India.
[6] Department Anesthesiology, Surya Children Hospital, Mumbai, Maharashtra, India.

Address of Correspondence
Dr. Vrushali Ponde,
Consultant Paediatric Anaesthesiologist, Surya Children Anaesthesia Services, Mumbai, Maharashtra, India.

Clinical Pearl for a Successful and Safe PNS Guided Peripheral Nerve Block

 Pre-procedural evaluation with history of antiplatelet or antithrombotic drug use
 Assess neurological status in patient with trauma and neuropathy
 Explain the procedure and complications
 Possibilities of failure of the procedure, multiple injections and conversion to GA must be explained
 Obtain informed written consent

 Perform the block in a dedicated block room or in OT
 Confirm the site before starting the procedure
 Block room must be equipped with monitoring devices and equipment
 Ensure all resuscitative emergency drugs, equipment and Intralipid present in the cart
 Secure venous access before performing the procedure
 Connect monitor for ECG, Non-invasive blood pressure (NIBP), and peripheral oxygen saturation

 STOP BEFORE YOU BLOCK: Confirm again about patient and site of block
 Calculate and keep drugs needed for block in labelled syringes ready before the procedure
 Maintain asepsis throughout the procedure
 A small dose of sedative / anxiolytic may be necessary for anxious patients. Infiltrate the injection site with lignocaine.
 Positive electrode is Red, and negative is Black (Positive is attached to patient, negative end is attached to the Needle). Machines may have different colour coding for the electrodes
 PNS stimulation is not possible in patient receiving neuromuscular blocking agent
 Presence of neuraxial anaesthesia doesn’t affect the stimulation of intact motor unit by PNS

 Always use insulated needle
 For superficial blocks: Use 50 mm needle, current at 1.0 mA.
 For deeper blocks: Use 100 mm needle, current at 1.5 mA
 Set PNS in 0.2ms current duration & frequency at 2 Hz.
 End motor response (EMR) between 0.3mA to 0.5mA is considered safe and ideal (except lumbar plexus block where below 0.5mA is unsafe).
 For children 25mm needle is preferred.
 Repeated aspiration before injection of drug at 3-5ml aliquot is a safe practice.
 Never try to inject against high resistance, use of injection pressure monitoring device is advisable.
 Keep talking to the patient while injecting the drug for early detection of the signs of the toxicity.
 Injection of Dextrose solution is preferred over sodium chloride for hydro dissection as saline will abolish muscle twitches.


Nerve Block Response
Interscalene Brachial plexus block Any two contractions of pectoralis major, deltoid, triceps or biceps.
Supraclavicular Brachial plexus block Finger or wrist twitches (flexion or extension)
Infraclavicular Brachial Plexus Block Posterior cord response is desirable (Extension of wrist and fingers)
Axillary Brachial Plexus Block Median nerve- Flexion of first three fingers

Musculocutaneous nerve- Elbow flexion Radial nerve- Fingers extension

Ulnar nerve- Flexion of fourth &little finger along with apposition of thumb towards little finger

Femoral Nerve Block Dancing of patella (Twitches of quadriceps muscle)
Sciatic Nerve Block Planter flexion or dorsi flexion
Lumbar Plexus Block Quadriceps contraction
Ilioinguinal & Iliohypogastric Nerve Block Lower Abdominal muscle & Inguinal region Twitches (T10-L1 territory)
Thoracic Paravertebral Block Corresponding intercostal muscles twitches
Serratus Anterior Plane (SAP) Block Serratus anterior muscle twitches/ Dancing of Scapula.
PEC1 Block Pectoralis Major muscle twitches


 Document the procedure. Date, Time, Needle type, size, disappearance of EMR at what current, setting of the PNS before injection of the drug, injection resistance or ease of injection, tingling or numbness during or immediately after injection, vitals etc.
 Assessment of Dermatome, Myotome and osteotome at 30minute. If all are blocked, then only we can proceed for incision and surgery


How to Cite this Article: Roy R, Das H, Singh N, Giri S, Vadera H, Ponde V | Clinical Pearl For A Successful And Safe PNS Guided Peripheral Nerve Block | July-December 2021; 2(2): 143-144.


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A Quick Guide: Ultrasound Guided Nerve Blocks

Vol 2 | Issue 1 | January-June 2021 | Page 02-03 | Vrushali Ponde, Kapil Gupta, Neha Singh

DOI: 10.13107/ijra.2021.v02i01.016

Authors: Vrushali Ponde [1], Kapil Gupta [2], Neha Singh [3]

[1] National President and Ex founder secretary, Academy of Regional Anaesthesia, India.
[2] Department of Anaesthesia, V.M.M.C & Safdarjung Hospital, New Delhi, India.
[3] Department of Anaesthesia, AIIMS, Bhubaneshwar, Odisha, India.

Address of Correspondence
Dr. Vrushali Ponde,
National President and Ex founder secretary, Academy of Regional Anaesthesia, India.

Ultrasound Machine and Image Acquisition Scanning Preparation
1. Obtain written informed consent for the block- AORA Written Consent Form
2. Re-examine the patient before administering the block
3. Checklist ticked before the block –(anaesthesiologist and nurse to be present)

AORA Checklist
– Ensure we have correct patient/block and marked site/side of block
– Check Documents and Equipment before initiating the procedure
– I.V cannula secured before performing the block
-Minimum ASA standard monitoring (pulse oxymeter, NIBP, ECG) started

4. Ergonomics- Ultrasound machine should be in direct line of sight of the anaesthesiologist performing the block
5. Selection of Pre-Set in certain machines to better visualize that structure (eg: Nerves/ Musculoskeletal/Vascular)
6. Probe selection – High frequency probe (13-6 MHz) for superficial nerves/structures and Low frequency probe (5-2 MHz) for deeper nerves/structures and neuraxial blocks
7. Tegaderm, Cling Wrap or Camera Cover wrapped around the probe for sterility
8. Oxygen administration via ventimask /nasal prongs
9. I.V. sedation like Midazolam /Fentanyl I.V. before initiating the block, but after finishing timeout/checklist
10. Maintenance of strict asepsis during the block procedure- AORA Sterility Precautions
11. Skin infiltration with 1% Lignocaine 1 min before inserting the needle; at the site of needle entry
12. Probe holding: Pen holding method is preferable for most blocks
13. At end of procedure- probe should be cleaned with Soap and water

Image Optimisation
The following movements of the probe can be utilized for optimization of image:
Transducer Movements:
1. Sliding
2. Tilting
3. Rocking
4. Rotation
5. Compression

Needle Approaches
In Plane- Whole length of the needle is visualized
Out of Plane- Only needle tip is visualized

Clinical Pearls
1. Optimize the image by setting the appropriate focus, depth and gain
2. Focus the target in centre of the screen
3. Ensure that the skin sterilizing solution has dried, before inserting the needle for block, as contact of sterilizing solution with the nerve can lead to nerve injury (neuropraxia /neurotemesis /axonotemesis)
4. Incremental injection of Local Anaesthetic in 2-3 ml aliquots after repeated aspiration
5. Stop administration of perineural drug, if the patient complains of pain during injection; as it can be a feature of intraneural injection of drug and lead to nerve injury
6. When using peripheral nerve stimulator, never inject the drug, if muscle contraction occurs at current less than 0.3 MA; as it can be a feature of intraneural (intrafascicular) administration of drug and cause nerve injury
7. Scan with the Colour Doppler while doing Brachial Plexus Block (especially Interscalene and Infraclavicular blocks); to avoid inadvertent intravascular injection
These practical tips decrease the potential complications, making ultrasound guided regional anaesthesia a safer technique. Acquisition of a better image improves the success rate of the block.

From the protocols and guidelines committee of AORA

Dr. Kapil Gupta
Professor, Anesthesiology,
V.M.M.C & Safdarjung Hospital, New Delhi, India.

Dr. Neha Singh
Additional Professor, Anesthesiology,
AIIMS, Bhubaneshwar, Odisha, India.

How to Cite this Article: Ponde V, Gupta K, Singh N | A Quick Guide: Ultrasound-Guided Nerve Blocks | International Journal of Regional Anaesthesia | January-April 2021; 2(1): 02-03.

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