Spinal block

Spinal block

Diagram of spinal block procedure

Diagram of spinal block procedure

ICD-10	3E0U3BZ
ICD-9	03.31
MeSH	D013127

A spinal block, also known as spinal anesthesia, is a form of regional anesthesia involving the injection of a local anesthetic into the subarachnoid space of the spinal cord. This procedure results in a temporary loss of sensation and motor function in the lower part of the body, making it particularly useful for surgeries involving the lower abdomen, pelvis, and lower extremities.

Indications

Spinal blocks are commonly used for:

• Cesarean section
• Hernia repair
• Orthopedic surgery on the lower limbs
• Urological procedures

Procedure

The procedure for administering a spinal block involves several steps:

Preparation

1. Patient Positioning: The patient is typically positioned in a sitting or lateral decubitus position to allow access to the lumbar region. 2. Aseptic Technique: The skin over the lumbar spine is cleaned with an antiseptic solution to reduce the risk of infection.

Needle Insertion

1. Identification of the Injection Site: The anesthesiologist identifies the appropriate intervertebral space, usually between L3-L4 or L4-L5. 2. Needle Insertion: A spinal needle is inserted through the skin, subcutaneous tissue, and interspinous ligaments into the subarachnoid space. 3. Confirmation of Placement: The correct placement is confirmed by the free flow of cerebrospinal fluid (CSF) through the needle.

Injection

1. Injection of Anesthetic: A local anesthetic, such as bupivacaine or lidocaine, is injected into the subarachnoid space. 2. Onset of Anesthesia: The onset of anesthesia is rapid, typically within 5-10 minutes.

Mechanism of Action

The local anesthetic blocks nerve conduction by inhibiting sodium channels in the neuronal membrane, preventing the propagation of action potentials. This results in a loss of sensation and motor function in the areas innervated by the affected nerves.

Advantages

• Rapid onset of anesthesia
• Reduced risk of systemic toxicity compared to general anesthesia
• Preservation of consciousness
• Decreased postoperative nausea and vomiting

Complications

While generally safe, spinal blocks can have complications, including:

• Hypotension
• Post-dural puncture headache
• Infection
• Nerve damage

Contraindications

Spinal blocks are contraindicated in patients with:

• Coagulopathy
• Infection at the injection site
• Severe hypovolemia
• Increased intracranial pressure

Also see

• Epidural anesthesia
• General anesthesia
• Local anesthesia
• Regional anesthesia