Peripheral nerve block

• Peripheral Nerve Blocks (PNB)

  Injecting a Local Anaesthetic Agents near or around the nerve or nerve plexus that supplies the surgical area
• Peripheral Nerve Blocks

  • Versatile anaesthetic techniques which do not incur significant haemodynamic changes provided that precautions is taken to avoid complications
  • Inadvertent intravascular injections
  • Intrathecal injection (interscalene)
  • Pneumothorax (supraclavicular)
• General Indications for Peripheral Nerve Blocks

  • Poor/high risk patient for general anaesthesia and central neuraxial blockade
  • Patient with metabolic disorders
  • Respiratory diseases
  • Patient with full stomach
  • Patient's request
• Contraindications for Peripheral Nerve Blocks

  • Patient's refusal
  • Uncooperative patient
  • Patient with distorted anatomy
  • Pre-existing neurological diseases
  • Infection at the proposed site of block
• Advantages of Peripheral Nerve Blocks

  • Avoidance of GA in high risk patients
  • Stable haemodynamics
  • Effective & extended perioperative pain control
  • Avoidance of opioids especially in elderly
  • Reduced incidence of postoperative nausea & vomiting
  • Allows early mobilisation & physiotherapy of major joints
  • No effect on bowel & bladder function
  • Antithrombolytic, therefore reduced risk of DVT
• Specific Preparation for Peripheral Nerve Blocks

  • Explanation and consent
  • Instructions to Patients/Assistants
  • Choice of Local anesthetic Agents
  • Equipment for resuscitation
  • Positioning the patient
  • Preparation of area to be blocked
  • Choosing the nerves to block
  • Single or Multiple Injections
  • Possible failure/Plan B
• Techniques for Locating the Nerve

  • Landmarks/ Anatomy
  • Paresthesia
  • Nerve stimulator
  • Ultrasound Machine
• Brachial Plexus Block


  Injection of local anesthetic adjacent to brachial plexus
• Approaches for Brachial Plexus Block

  • Interscalene
  • Supraclavicular
  • Infraclavicular
  • Axillary
• Axillary Approach

  • Patient lies supine, head turned opposite the side to be blocked
  • The arm to be blocked is abducted to a right angle, externally rotated and flexed at the elbow
  • It is a sterile procedure
  • Axillary artery is identified, and needle is inserted laterally
  • Should blood be aspirated, the needle can be withdrawn and be re-inserted laterally to the artery
• Axillary Block

  • Indication for surgery involving the elbow, forearm and hand
  • Targets three of the four major terminal nerves of the brachial plexus: ulnar, radial, and median nerves
  • The axillary nerve itself is not blocked
  • Multiple injections are used to target these nerves
  • The patient lies in the supine position with abduction of the arm to be blocked
  • Excessive abduction is avoided since it stretches the brachial plexus increasing vulnerability to injury
  • Landmarks are the axillary artery, the biceps, coracobrachialis, and triceps muscle
• Brachial Plexus Block - Axillary

  • Most common approach to the brachial plexus
  • Provides an excellent block for procedures distal to the elbow
  • Low complication rate, provided intravascular injection is avoided
  • Repeated elicitation of paraesthesia at multiple sites may increase the incidence of postoperative neuropathies
  • Hematoma and infection are very rare
• Intravenous Regional Anaesthesia (IVRA) - Bier's block

  Injection of local anesthetic agents intravenously for anesthesia of an extremity
• Indications for IVRA (Bier's block)

  • Suitable for operations in the hand and forearm (e.g. excision of ganglion, manipulation of fractures, and suturing of lacerations)
  • May also be used for operation in the foot and leg, though it is not often used for this purpose because of the larger volume of local anaesthetic required
• Contraindications for IVRA (Bier's block)

  • Sickle cell anaemia
  • Raynaud's disease
• Drugs used for IVRA (Bier's block)

  • 0.5% prilocaine
  • 0.5% lignocaine
  • 0.25% bupivacaine
  • Plain solution without adrenaline is used
• Advantages of IVRA (Bier's block)

  • Relatively easy to perform
  • Rapid onset of action
  • Rapid recovery
• Disadvantages of IVRA (Bier's block)

  • Duration limited by tolerance of tourniquet pain
  • Risk of systemic toxicity
• Major nerves that supply the Lower Limb

  • Femoral nerve
  • Lateral femoral cutaneous nerve
  • Obturator nerve
  • Sciatic nerve
• Nerves that arise from the Lumbar plexus

  • Femoral nerve
  • Lateral femoral cutaneous nerve
  • Obturator nerve
• Sciatic nerve


  Arises from the Lumbosacral plexus and provides sensory & motor supply to part of pelvis, posterior thigh, most of the lower leg & entire foot
• Disadvantages of Lower Limb Blocks

  • Inadequate training of consultants & resident doctors
  • Takes time to be performed & for block to set – most FNB & Sciatic nerve block take 15-30 minutes to be effective
  • Failure rate is 5% even in the best of hands
• Sciatic Block

  • The sacral plexus provides motor and sensory innervation to the entire lower extremity including hip, ankle and knee
  • Landmarks are the greater trochanter, the posterior superior iliac spine, and the sacral hiatus
  • Twitch monitors may be used with the goal of visible or palpable twitches of the hamstrings, calf muscles, foot or toes
  • The patient needs adequate sedation; commonly painful
  • Onset of block usually occurs in 10-25 minutes
  • Provides for complete anesthesia of the leg except for the medial strip of skin innervated by the saphenous nerve
  • Combined with a femoral block, complete anesthesia of the leg may be achieved
• Indications for Sciatic Nerve Block

  • Ankle surgery
  • Foot surgery
  • Knee surgery (combined with femoral nerve block)
• Femoral Nerve Block

  • Femoral nerve is covered by fascia iliaca at femoral crease
  • Indications: Surgery of the anterior thigh, Knee arthroscopy/surgery, Analgesia for femoral shaft fracture
• Three-in-One Block

  • Femoral nerve is the only nerve consistently blocked through this approach
  • LA diffusion laterally blocks lateral femoral cutaneous nerve NOT proximal spread
  • Anterior diffusion blocks obturator nerve slightly
  • 3 in 1 block is achieved
• Popliteal Block

  • Indication: foot & ankle surgery
  • Popliteal block – entire leg below tibial plateau except medial calf & foot (saphenous)
  • Approaches: posterior or lateral
  • Landmark: 8 – 10cm from the base of popliteal triangle
• Nerves Blocked in Ankle Block

  • Posterior tibial
  • Superficial peroneal
  • Deep peroneal
  • Sural nerve
  • Femoral saphenous nerves
• Ankle Block

  • Indicated for surgery of the foot
  • The pertinent landmarks are the posterior tibial and dorsalis pedis arteries, tendon of the hallucis longus and medial malleolus
• A good knowledge of the anatomy of the nervous system and the pharmacology of Local Anaesthetics is indispensible to performing a good peripheral block
• It is also important to keep in mind the possible complications and take necessary preventive measure