Epidural basics

What an epidural is (and why we use it)

• An epidural delivers local anaesthetic (often with an opioid) into the epidural space via a catheter to reduce pain.
• Common uses: labour analgesia, post-op analgesia (e.g. major abdominal/thoracic/orthopaedic surgery), rib fracture pain.
• Aims: good pain relief, minimise systemic opioids, enable breathing/physio/mobilisation (when appropriate).
• Effect: blocks nerve roots as they pass through the epidural space → reduced pain; may also cause numbness and weakness depending on dose/spread.

Key anatomy and landmarks (starter level)

• Epidural space lies outside the dura (the membrane around the spinal cord/CSF).
• Typical approach: midline or paramedian between spinous processes.
• Landmarks: iliac crests roughly at L4; common labour levels L2–3 or L3–4; thoracic epidurals are higher and more technically demanding.
• Loss of resistance (LOR) technique identifies epidural space; most UK practice uses saline.
• Depth varies widely (body habitus, level). Never advance needles without control and incremental steps.

Indications (common first-time scenarios)

• Labour: maternal request, prolonged labour, instrumental/operative delivery planning, high opioid sensitivity, some high-risk cardiac/respiratory situations (individualised).
• Post-op: major open abdominal surgery, thoracotomy, oesophagectomy, major vascular surgery (local policy dependent).
• Acute pain: multiple rib fractures (consider alongside regional alternatives).
• Facilitates conversion to surgical anaesthesia in labour (top-up), but always plan for failure and escalation.

Contraindications and ‘stop and think’ checks

• Absolute: patient refusal, infection at insertion site, uncorrected severe coagulopathy/unsafe anticoagulation timing, true allergy to intended drugs (rare).
• Relative: systemic sepsis, significant hypovolaemia/shock, raised intracranial pressure from a mass lesion, severe spinal deformity/previous surgery, fixed cardiac output states (needs senior input).
• Always check: platelet count if indicated, anticoagulant/antiplatelet history and timing, baseline neuro exam (leg strength/sensation), haemodynamics, and ability to cooperate/position.
• If unsure about anticoagulation safety: pause and check local neuraxial guideline (ASRA/ESAIC-informed) or call a senior.

Consent and communication (what to cover simply)

• Explain: what it is, expected benefits, what it feels like (pressure, not sharp pain), and that it may not be perfect.
• Common side effects: low blood pressure, itch (if opioid used), shivering, urinary retention, leg heaviness/weakness.
• Important risks to mention: accidental dural puncture/headache, inadequate block, infection, bleeding/epidural haematoma (rare), nerve injury (very rare).
• Set expectations: pain should improve significantly but may need adjustments; ask them to report one-sided pain, severe back pain, new weakness, or numbness.

Equipment and preparation (safe setup)

• Standard monitoring: BP, ECG, SpO2; ensure IV access is working.
• Resuscitation readiness: vasopressor available (e.g. metaraminol/phenylephrine as per local practice), fluids available, oxygen and suction ready.
• Asepsis: hat/mask, sterile gown/gloves, skin prep with appropriate antiseptic, sterile drapes; minimise talking over the field.
• Epidural kit: Tuohy needle, LOR syringe (saline), catheter, filter, sterile dressing, labels; infusion pump and prescribed solution ready.
• Positioning: sitting or lateral; maximise flexion while maintaining comfort and safety; ensure stable support to prevent sudden movement.

Technique overview (high-level, stepwise)

• Identify level and midline; infiltrate skin with local anaesthetic.
• Advance Tuohy needle carefully to ligamentum flavum region; use LOR to saline to identify epidural space.
• Thread catheter (typical 3–6 cm in epidural space; follow local policy). Avoid excessive threading (higher risk of unilateral/vascular placement).
• Aspirate gently (blood/CSF check). Apply filter and secure with a clear dressing; label clearly.
• Document: level, approach, depth to space, catheter length at skin, aspiration findings, test dose (if used), initial dose, and patient response.

Test dose and initial dosing (principles)

• Purpose: reduce risk of unrecognised intrathecal or intravascular placement (no test is perfect).
• Common approach: small incremental doses with frequent checks (BP, HR, symptoms, sensory level). Some settings use a formal test dose (e.g. lidocaine with adrenaline) depending on local policy.
• Dose slowly and reassess: pain relief, sensory level, leg strength, haemodynamics.
• If signs of high/total spinal (rapid dense block, hypotension, difficulty breathing): stop dosing, call for help, support airway/breathing/circulation immediately.

Ongoing management (ward/labour ward basics)

• Analgesia delivery: infusion, programmed intermittent bolus, and/or patient-controlled epidural analgesia (PCEA) depending on local practice.
• Regular observations: pain score, sensory level, motor block (e.g. Bromage), BP/HR, sedation/respiratory rate if opioid used, catheter site and dressing.
• Escalate early if: increasing pain despite boluses, unilateral block, dense motor block, hypotension, fever/back pain, or neurological symptoms.
• Ensure clear plan for anticoagulation around catheter removal and post-removal monitoring (follow local neuraxial guideline).

Troubleshooting: common ‘first on-call’ problems

• Unilateral block: reposition patient to painful side down, give a cautious top-up, consider withdrawing catheter 1 cm (with asepsis) if too deep; seek senior help if persistent.
• Patchy/inadequate block: check catheter connections, pump function, and filter; give incremental bolus; consider re-siting if repeated failure.
• Hypotension: left uterine displacement in pregnancy, fluids as appropriate, vasopressor per local protocol, reduce/stop dosing if needed; reassess block height.
• Itch/nausea: consider opioid-related; treat symptomatically (antiemetic, low-dose naloxone infusion in selected cases per local policy).
• Leg weakness: assess motor block; if unexpectedly dense or progressive, stop infusion and urgently review for high block or neuraxial complication.

Complications you must not miss

• Accidental dural puncture: may cause post-dural puncture headache (worse upright, better lying flat) 24–72 h later; inform patient, document, and refer to anaesthetics for follow-up.
• Epidural haematoma (rare, time-critical): severe back pain, new/progressive weakness or numbness, bladder/bowel dysfunction—urgent MRI and neurosurgical input.
• Epidural abscess (rare): fever, back pain, neurological symptoms—urgent imaging and specialist review.
• Local anaesthetic systemic toxicity (LAST): tinnitus, metallic taste, agitation, seizures, arrhythmias—stop drug, call for help, follow intralipid protocol.
• High/total spinal (usually from intrathecal dosing): hypotension, bradycardia, difficulty breathing, loss of consciousness—immediate airway support and vasopressors; call for senior help.

Removal and aftercare (basics)

• Remove with aseptic technique; check catheter tip is intact and document removal time/date and condition of site.
• Coordinate with anticoagulation timing (both insertion and removal carry bleeding risk). If timings are not clearly safe, do not remove—seek advice.
• After removal: continue neuro observations as per local policy; instruct patient to report new back pain, weakness, numbness, or bladder issues.
• Ensure alternative analgesia is prescribed before stopping/removing the epidural (avoid rebound pain).