Regional anesthesia
1. Brachial Plexus Block (for upper limb anesthesia)
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Injection site:
- Interscalene block: At the level of C6, between the anterior and middle scalene muscles.
- Supraclavicular block: Above the clavicle, near the brachial plexus trunks.
- Infraclavicular block: Below the clavicle near the cords of the brachial plexus.
- Axillary block: Near the axillary artery, at the level of the axilla.
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Clinical relevance: Used for surgeries of the shoulder, arm, forearm, and hand.
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Key point: Interscalene block can cause phrenic nerve paralysis (C3-C5), leading to diaphragmatic hemiparalysis.
2. Epidural Anesthesia
- Injection site:
- Into the epidural space, typically at lumbar levels (L3-L4, L4-L5), via the ligamentum flavum.
- Clinical relevance: Used for labor analgesia, lower limb and abdominal surgeries.
- Key point: Avoid dural puncture to prevent post-dural puncture headache.
3. Spinal Anesthesia
- Injection site:
- Into the subarachnoid space, usually at L3-L4 or L4-L5 interspace.
- Clinical relevance: Used for lower limb, pelvic, and lower abdomen surgeries.
- Key point: Fast onset and denser block; risk of hypotension due to sympathetic blockade.
| Feature | Epidural Anesthesia | Subarachnoid (Spinal) Anesthesia |
|---|---|---|
| Injection site | Epidural space | Subarachnoid space (CSF) |
| Onset | 10-20 min | 2-5 min |
| Duration | Variable, hours to days (infusion possible) | Limited to single shot duration (1.5-4 h) |
| Block density | Segmental; can be titrated | Dense and profound motor and sensory block |
| Sympathetic blockade | Variable, less profound | Usually marked hypotension |
| Use | Labor analgesia, postoperative pain control, major thoracoabdominal surgery | Lower limb, pelvic, lower abdominal surgery with rapid onset |
| Main complications | Epidural hematoma/abscess, accidental dural puncture, patchy block | Post-dural puncture headache, hypotension, total spinal |
4. Sciatic Nerve Block
- Injection site:
- Posteriorly in the gluteal region or mid-thigh.
- Clinical relevance: Used for anesthesia of the lower limb below the knee.
- Key point: Useful in foot and ankle surgeries.
5. Femoral Nerve Block
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Injection site:
- Just distal to the inguinal ligament, lateral to the femoral artery and vein. The nerve lies lateral to the femoral artery in the femoral triangle.
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Clinical relevance:
- Provides anesthesia to the anterior thigh, knee, and medial leg (via saphenous nerve branch).
- Frequently used in surgeries involving the anterior thigh, knee arthroscopy, or for pain control after femur fractures.
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Anatomical landmarks:
- Needle insertion usually at the level of the femoral triangle, found using the inguinal ligament superiorly, sartorius muscle laterally, and adductor longus muscle medially.
- Palpate femoral artery, insert needle just lateral to artery.
6. Digital Nerve Block
- Injection site:
- At the base of the fingers, near the digital nerves.
- Clinical relevance: For finger surgeries.
- Key point: Avoid intravascular injection to prevent systemic toxicity.