Question

Segmental spinal anaesthesia.

Hint:

Segmental spinal anaesthesia provides effective regional analgesia, particularly for lower abdominal and lower limb surgeries, with fewer systemic effects compared to general anaesthesia.

Answer 1

Step 1: Introduction to Segmental Spinal Anaesthesia.
Segmental spinal anaesthesia (SS is a form of regional anaesthesia in which the anaesthetic is administered to specific segments of the spinal cord to provide targeted sensory and motor blockade. It is most commonly used in spinal blocks where the goal is to achieve pain relief and muscle relaxation in specific regions, usually for procedures involving the lower body. SSA is commonly used for lower limb surgeries, abdominal surgeries, or pelvic surgeries.
Step 2: Mechanism of Segmental Spinal Anaesthesia.
- Segmental spinal anaesthesia involves the injection of local anaesthetic (L into the subarachnoid space (spinal canal) to block nerve roots at specific spinal levels. The level of anaesthesia depends on the amount and concentration of the LA injected.
- The local anaesthetic used for SSA blocks the conduction of nerve impulses in the dorsal root ganglia and nerve roots. This leads to the desired motor and sensory blockade in a specific segment or region.
Step 3: Applications of SSA.
(1) Surgical Applications:
- SSA is particularly useful for lower abdominal, pelvic, and lower limb surgeries. It provides effective pain control during surgery while allowing for conscious sedation in some cases. Examples include:
- Caesarean sections.
- Hernia repairs.
- Hip or knee surgeries.
(2) Obstetric Anaesthesia:
- SSA is widely used in obstetric procedures for pain relief during labour or Caesarean section. It provides good segmental pain control, allowing the mother to be conscious during the delivery.
Step 4: Advantages of SSA.
(1) Targeted Blockade:
- Unlike general anaesthesia, SSA provides segmental control, allowing the surgeon to perform the procedure without affecting other parts of the body.
- The anaesthesia can be tailored to specific levels, depending on the surgery.
(2) Reduced Risk of Systemic Effects:
- The risk of systemic side effects (e.g., respiratory depression, nausea, vomiting) is reduced compared to general anaesthesia.
(3) Faster Recovery:
- Patients recover quickly from SSA, with a rapid return of motor and sensory function post-procedure.
Step 5: Technique and Considerations.
(1) Positioning:
- The patient is usually positioned sitting or lateral (on their side), with the back arched to facilitate access to the lumbar spine.
- Aseptic technique is crucial to prevent infection.
- Needle Placement: A fine needle is inserted between the lumbar vertebrae, typically at L3-L4 or L4-L5, into the subarachnoid space.
- Volume and Type of Anaesthetic: The volume and type of local anaesthetic (e.g., bupivacaine, lidocaine) are chosen based on the surgical site and duration of the procedure.
(2) Complications:
- Hypotension: A common complication, especially if the block spreads too high. It can be managed with fluids and vasopressors.
- Postdural puncture headache (PDPH): Caused by leakage of cerebrospinal fluid from the puncture site.