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Spinal anaesthesia involves a single injection into the cerebrospinal fluid with rapid onset and is typically used for shorter procedures. Epidural anaesthesia involves placing a catheter into the epidural space for continuous or repeated dosing, suitable for longer procedures or extended pain relief.

Anatomy

Information

• Spinal and epidural anaesthesia are both regional anaesthetics used to block pain in a specific area of the body, most commonly during childbirth or certain types of surgery. However, there are key differences between the two:

Spinal Anaesthesia

• Injection Site: Spinal anaesthesia is injected into the cerebrospinal fluid (CSF) in the subarachnoid space, which is within the spinal cord.
• Onset and Duration: It has a rapid onset of action, usually within a few minutes, and typically lasts for about 1-2 hours. Needle Size: The needle used for spinal anaesthesia is finer and smaller compared to that used for epidural anaesthesia.
• Effect: Spinal anaesthesia provides a more profound and complete block, affecting both sensory and motor functions. Single Injection: It is usually administered as a single injection, without the need for a catheter.

Epidural Anaesthesia

• Injection Site: Epidural anaesthesia is injected into the epidural space, which is outside the dura mater, the outermost membrane covering the spinal cord.
• Onset and Duration: It has a slower onset of action, taking about 10-20 minutes to take full effect. It can be used for longer durations, sometimes maintained for several days.
• Needle Size: The needle used for epidural anaesthesia is larger because it needs to accommodate a catheter.
• Effect: Epidural anaesthesia provides a more controlled block, often affecting sensory functions more than motor functions. This can be adjusted by varying the dosage of anaesthetic.
• Catheter Use: A catheter is typically placed in the epidural space, allowing for continuous or repeated administration of the anaesthetic, making it suitable for prolonged procedures or pain management.

Applications

• Spinal Anaesthesia: Commonly used for surgeries below the umbilicus, such as lower limb surgeries, caesarean sections, and some types of abdominal surgery.
• Epidural Anaesthesia: Frequently used for labour and delivery, as it allows for pain relief during childbirth while maintaining the ability to push. It is also used for surgeries and procedures requiring longer pain management.