LOCAL ANAESTHETIC TECHNIQUES

Central Block: Spinal and Epidural Anaesthesia

Procedure including Anatomy

Spinal and epidural anaesthesia are regional anaesthetic techniques that involve the injection of local anaesthetics into the spinal canal or epidural space, respectively. Understanding the anatomy is crucial for performing these procedures safely and effectively.

1. Anatomy:
   • Spinal Column: The spinal column consists of vertebrae, intervertebral discs, and surrounding structures. It houses the spinal cord, which extends from the brainstem to the lumbar region.
   • Epidural Space: This is the outermost space surrounding the spinal cord, located between the dura mater (the outermost meningeal layer) and the bony vertebrae. It contains fat, blood vessels, and nerve roots.
   • Subarachnoid Space: Located beneath the arachnoid mater, this space contains cerebrospinal fluid (CSF) and is where spinal anaesthesia is administered. The needle must penetrate through the skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, ligamentum flavum, and finally into the subarachnoid space.
2. Procedure Steps:
   • Preparation: The patient should be positioned appropriately (sitting or lying down), with aseptic technique maintained.
   • Identification of Landmarks: Palpation of spinous processes to identify appropriate intervertebral spaces (commonly L3-L4 or L4-L5).
   • Needle Insertion: A spinal needle is inserted through the skin into the subarachnoid space for spinal anaesthesia or an epidural needle for epidural anaesthesia.
   • Injection of Anaesthetic: Local anaesthetic is injected; in spinal anaesthesia, it enters CSF directly; in epidural anaesthesia, it diffuses through the dura mater into the CSF.

Indications and Contraindications

1. Indications:
   • Surgical procedures below the umbilicus (e.g., lower limb surgery).
   • Pain management during labor and delivery.
   • Certain diagnostic procedures (e.g., lumbar puncture).
2. Contraindications:
   • Infection at injection site or systemic infection.
   • Coagulopathy or anticoagulant therapy increasing bleeding risk.
   • Severe hypovolemia or hemodynamic instability.
   • Pre-existing neurological disorders affecting safety.

Complications (Prevention and Treatment)

1. Complications of Spinal Anaesthesia:
   • Hypotension: Due to sympathetic blockade; managed with IV fluids and vasopressors if necessary.
   • Post-Dural Puncture Headache (PDPH): Caused by CSF leakage; treated with hydration, caffeine intake, or an epidural blood patch if severe.
   • Neurological Injury: Rare but can occur due to direct trauma or hematoma formation; prevention involves careful technique.
2. Complications of Epidural Anaesthesia:
   • Inadequate Analgesia/Anesthesia: May require repositioning or additional doses; assess placement via test dose.
   • Epidural Hematoma/Abscess Formation: Risk factors include anticoagulation; immediate surgical intervention may be required if symptoms develop.
   • Transient Neurological Symptoms (TNS): Characterized by pain in buttocks/legs post-procedure; usually self-limiting.
3. Prevention Strategies:
   • Maintain strict aseptic technique to prevent infections.
   • Use ultrasound guidance when necessary to improve accuracy in needle placement.
   • Monitor vital signs closely during and after administration to detect complications early.

In summary, both spinal and epidural anaesthesia are valuable techniques for managing pain during surgical procedures and labor. A thorough understanding of anatomy, indications/contraindications, potential complications along with their prevention strategies ensures safe practice.

I.V.R.A. (BIER BLOCK)

Intravenous Regional Anesthesia (IVRA), commonly known as Bier block, is a technique that involves the injection of local anesthetic into the venous system of an isolated extremity, which has been exsanguinated and occluded from central circulation using a tourniquet. This method provides localized anesthesia for surgical procedures on the upper or lower limbs, typically lasting up to two hours.

Procedure: Intravenous Regional Anesthesia (IVRA), commonly known as the Bier block, is performed using the following steps:

1. Preparation:
   • Ensure monitoring equipment is attached and resuscitation equipment is ready.
   • Insert two intravenous (IV) lines: one in the forearm close to the surgical site and another in the opposite arm for fluid resuscitation and systemic medications if needed.
2. Exsanguination:
   • Elevate the extremity for 2-3 minutes to facilitate passive drainage.
   • Apply a roll of gauze in the patient’s hand to reduce discomfort from the Esmarch bandage.
   • Use an Esmarch bandage to actively exsanguinate the extremity.
3. Tourniquet Application:
   • After ensuring a double-cuffed tourniquet is in place, inflate the distal cuff to 250 mmHg or 100 mmHg above systolic blood pressure, followed by inflation of the proximal cuff.
   • The tourniquet should remain inflated for at least 30 minutes but no longer than 60 minutes.
4. Anesthetic Injection:
   • Confirm that brachial and radial pulses are not palpable before injecting local anesthetic.
   • Slowly inject local anesthetic into the IV line to avoid spread past the tourniquet. Typical dosing includes approximately 40 mL of 0.5% lidocaine if placed above the elbow, or about 30 mL if below.
5. Post-Procedure:
   • Release the distal cuff and remove the Esmarch bandage after allowing sufficient time for anesthesia to take effect.

Indications and Contraindications:

• Indications:
  • IVRA is indicated for brief surgical procedures on the upper extremities such as ganglionectomy, carpal tunnel release, Dupuytren’s contracture surgery, or fracture reduction.
• Contraindications:
  • Contraindications include:
    • Allergy to local anesthetics
    • Known deep vein thrombosis (DVT)
    • Open wounds
    • Severe hypertension (>175 mmHg systolic)
    • Raynaud’s phenomenon
    • Sickle cell disease
    • Crush injuries
    • Unreliable tourniquet
    • Young children due to difficulty managing pain and anxiety during exsanguination.

Complications (Prevention and Treatment):

• Local Anesthetic Systemic Toxicity (LAST): LAST is uncommon but can occur with symptoms including cardiac arrest, seizures, hypotension, arrhythmias, and even death. Prevention strategies include:
  • Careful patient selection considering risk factors such as renal/hepatic dysfunction, ischemic heart disease, age extremes (<4 months or >79 years), pregnancy.
• Management of LAST: In case of LAST symptoms:
  • Provide supportive care including airway management and cardiovascular support.
  • Administer lipid emulsion therapy if severe toxicity occurs.
• Tourniquet Pain: If tourniquet pain develops during the procedure:
  • Inflate the distal tourniquet while deflating the proximal one to alleviate discomfort.

Overall, practitioners performing IVRA should be well-trained in recognizing and managing complications associated with this technique.