Spinal Anesthesia Procedure – A Step-by-Step Guide

Mastering Spinal Anesthesia: From Preparation to Completion

Spinal anesthesia, also known as subarachnoid block, is a widely used technique in modern medical practice to provide regional anesthesia and pain relief for various surgical procedures. It involves injecting a local anesthetic into the subarachnoid space of the spinal canal, leading to temporary loss of sensation and motor function in the lower half of the body.

Being a delicate procedure requiring precision and attention to detail, this step-by-step guide will walk you through the entire process of spinal anesthesia, from pre-procedure assessment to post-procedure care.

Step 1: Preparation (The Critical 10 Minutes)

  1. Patient Assessment:
    • Review coagulation status (platelets, INR, anticoagulants)
    • Assess airway and cardiorespiratory status
    • Verify NPO status
    • Obtain informed consent
  2. Equipment Setup:
    • Spinal tray with 25-27G pencil-point needle
    • Local anesthetic (bupivacaine 0.5% hyperbaric/isobaric)
    • Chlorhexidine or povidone-iodine solution
    • Sterile gloves, drapes, gauze
    • Monitoring equipment (ECG, NIBP, SpO₂)
  3. Positioning:
    • Lateral decubitus: Knees drawn to chest, neck flexed
    • Sitting position: Feet on stool, leaning forward
    • Ensure spine is parallel to floor and perpendicular to needle path

Step 2: The Procedure (The 5-Minute Window)Spinal Anaesthesia Procedure

  1. Landmark Identification:
    • Palpate iliac crests → Tuffier's line (L4 spinous process)
    • Mark L3-L4 or L4-L5 interspace
  2. Sterile Preparation:
    • Wide area prep with antiseptic solution
    • Drape with fenestrated sterile sheet
  3. Local Anesthesia:
    • Inject 1-2 mL lidocaine 1% at skin entry site
    • Aspirate before injection to avoid IV injection
  4. Spinal Needle Insertion:
    • Midline approach: 90° to skin in all planes
    • Paramedian approach: 10-15° medial angle
    • Advance through ligaments → "pop" at ligamentum flavum
    • Stylet removal → CSF flow confirmation
  5. Drug Injection:
    • Attach syringe with local anesthetic
    • Aspirate to confirm free flow of clear CSF
    • Inject drug slowly (0.2 mL/sec)
    • Note: No resistance should be felt
  6. Needle Removal:
    • Replace stylet before withdrawal
    • Apply pressure at puncture site

Step 3: Patient Monitoring and Management

  1. Vital Signs: Continuously monitor the patient's vital signs, including heart rate, blood pressure, oxygen saturation, and respiratory rate.
  2. Sensory and Motor Block Assessment: Assess the level of sensory and motor block by asking the patient to report sensations and perform simple movements.

Step 4: Post-Procedure Management

  1. Positioning:
    • Hyperbaric: Position to achieve desired level
    • Isobaric: Supine position
  2. Monitoring:
    • Vital signs every 2-5 minutes initially
    • Sensory level testing (pinprick/cold)
    • Motor blockade assessment (Bromage scale)
  3. Documentation:
    • Needle type and size
    • Local anesthetic dose and volume
    • Level of sensory blockade
    • Complications (if any)

Pro Tips for Success

  • Use ultrasound for difficult anatomy
  • Preload with 500-1000 mL crystalloid for hypotension prevention
  • Have vasopressors (phenylephrine/ephedrine) drawn up
  • Always have general anesthesia equipment available

Related Content

Need to refresh your anatomy? Review our Anatomy and Physiology guide for spinal anesthesia. And be prepared for any situation with our Complications and Management resource.

In conclusion, spinal anesthesia is a valuable technique used for a range of surgeries. This step-by-step guide emphasizes the importance of careful patient selection, precise needle placement, vigilant monitoring, and post-operative care to ensure the safety and effectiveness of the procedure.

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