Obstetric Debugging

1. Epidural Basics & Common Questions

  • Consent: Explain common risks (hypotension, catheter, nerve damage, infection)

    • Nerve damage: ~1:10,000-50,000

    • Infection: ~1:10,000-50,000

    • LAST: ~1:1,000-10,000

    • PDPH: 1:100 (more common with 16G)

    • Patchy/inadequate block: ~1:5-10

    • Hypotension: Very common (~1:2-3)

  • Needle size: 16G (better sensitivity, higher headache risk if dural puncture) vs. 18G (standard)

  • Loss of resistance: Saline (safer) vs. air (clearer feel but risk of air headache)

  • Test dose: 5 mL 0.2% ropivacaine or 0.25% bupivacaine to rule out intrathecal placement

  • Top-up doses: 5–12 mL increments (e.g., 5-10-5 regimen). Faster injection = wider spread

  • Epidural space depth: Usually 4-6 cm in average adult, deeper in obese patients

  • Drug onset: Bupivacaine 15-20 min, lidocaine 5-10 min, ropivacaine 10-15 min

  • Duration: Bupivacaine 2-4 hours, ropivacaine 2-3 hours, lidocaine 1-2 hours

  • Catheter insertion: Thread 3-5 cm into epidural space to prevent migration

2. Epidural Troubleshooting

  • Blood in catheter: Aspirate, retract catheter slightly, flush with saline. If persistent, replace

  • Patchy block: Retract catheter 1–2 cm (ensure ≥5 cm remains in space). Replace if ineffective

  • Dural puncture: Confirm CSF (check glucose). Options: Re-attempt at another level or thread catheter intrathecally

  • Disconnections: Secure filter-to-catheter connection to prevent contamination

  • Unilateral block: Patient positioning (affected side down), catheter manipulation, replace if persistent

  • Inadequate sacral spread: Higher volume, change patient position, consider caudal top-up

  • Motor block: Reduce concentration, increase volume, consider ropivacaine over bupivacaine

  • Catheter migration: Secure with transparent dressing, loop catheter to prevent tension

  • Failed insertion: Maximum 3 attempts, consider ultrasound guidance, senior help

3. Combined Spinal-Epidural (CSE)

  • CSE: Spinal + epidural in one procedure. Confirms midline placement, faster onset

  • DPE: Puncture dura with spinal needle (no drug), then thread epidural. Reduces patchy blocks

  • CSE advantages: Immediate analgesia, epidural backup, reduced drug requirement

  • CSE disadvantages: Two-needle technique, potential masking of epidural problems

  • Failure rates: CSE <1%

4. Spinal for Labour Analgesia

  • Indications: Late-stage labour, failed epidural, urgent pain relief

  • Dose: Low-dose (e.g., 1 mL 0.25% bupivacaine + fentanyl) to avoid high block

  • Positioning: Lateral decubitus reduces block height vs. sitting

  • Duration: 2-4 hours depending on drug choice and dose

  • Monitoring: Hourly BP, motor assessment, fetal monitoring

  • Complications: Hypotension (treat with ephedrine/phenylephrine), high block

  • Contraindications: Coagulopathy, infection, increased ICP, patient refusal

  • Drug combinations: Bupivacaine 2.5mg + fentanyl 25mcg is common

  • Repeat doses: Generally not recommended, consider epidural if analgesia wears off

5. Managing Epidural Contraindications

  • Platelets: ≥70k for epidural, ≥50k for spinal. Avoid if recent drop or bleeding disorder

  • IV PCA alternatives: Fentanyl 25-50mcg bolus, remifentanil 0.5-1mcg/kg bolus

  • Nitrous oxide: 50:50 mix with O₂, patient-controlled administration

  • Ketamine: 0.25-0.5mg/kg IV bolus, risk of hallucinations and hypertension

  • Coagulopathy assessment: PT/PTT, bleeding history, medication review

  • Anticoagulant timing: Warfarin (INR <1.5), heparin (stop 4-6h), LMWH (stop 12-24h)

  • Neurological contraindications: MS relapse, increased ICP, spinal cord lesions

  • Sepsis considerations: Avoid if bacteremia, local skin infection

  • Hypovolemia: Correct before neuraxial block to prevent severe hypotension

6. Epidural Top-Up for Cesarean Section

  • Drugs: 0.75% bupivacaine (slower onset, longer duration) or 2% lidocaine + adrenaline (faster, more hypotension)

  • Speed of injection: Slow for dense block without excessive spread

  • Failure rate: 1:5 epidurals fail vs. 1:15,000 spinals. Be prepared to convert to GA

  • Volume required: 15-25 mL depending on height and epidural space anatomy

  • Onset time: Lidocaine 5-10 min, bupivacaine 15-25 min

  • Block level required: T4-T6 for comfortable surgery

  • Additives: Fentanyl 50-100mcg, adrenaline 1:200,000 for lidocaine

  • Testing block: Ice, pinprick, loss of temperature sensation

  • Breakthrough pain: IV ketamine 0.5mg/kg, convert to GA if inadequate

7. General Anesthesia for Cesarean Section

  • Pre-op: Catheter, lateral tilt, antacids, ready drugs (thiopentone/propofol + suxamethonium +/- short acting opiate like Alfentanyl)

  • Airway: RSI with cricoid pressure. Secure tube before surgical start

  • Post-op: Ensure recovery protocols for pain/nausea (e.g., IV morphine PCA)

  • Failed intubation protocol: LMA, wake up if possible, emergency cricothyroidotomy

  • Aspiration prophylaxis: Ranitidine 150mg PO/IV, sodium citrate 30mL PO

  • Induction agents: Propofol 2-3mg/kg or thiopentone 5-7mg/kg

  • Muscle relaxation: Suxamethonium 1.5mg/kg, rocuronium 1.2mg/kg if contraindicated

  • Maintenance: Sevoflurane/isoflurane with 50% N₂O, avoid high concentrations (uterine relaxation)

  • Neonatal considerations: Minimise drug exposure, prepare for neonatal resuscitation

8. Ultrasound for Neuraxial Techniques

  • Use: Identify midline, depth, and interspace in obese/scoliotic patients

  • Technique: Curvilinear probe, mark skin before sterile prep

  • Practice: Train in elective cases before emergencies

  • Landmarks: Ligamentum flavum, dura mater, posterior complex

  • Imaging planes: Parasagittal oblique, transverse median

  • Depth measurement: Distance from skin to ligamentum flavum

  • Needle insertion: Real-time guidance or pre-procedural marking

  • Success rates: Improved first-pass success, reduced complications

  • Learning curve: 20-30 supervised procedures for competency

9. High-Risk Scenarios

  • Placenta accreta: Coordinate with blood bank, consider cell salvage, TXA

  • Cord prolapse: Immediate GA if spinal contraindicated

  • Manual placenta removal: Saddle block (S2–S5) or low spinal (T10)

  • Massive hemorrhage protocol: Activate early, O-negative blood, coagulation support

  • Eclampsia: Magnesium sulfate, antihypertensives, may need urgent delivery

  • Amniotic fluid embolism: Supportive care, early intubation, inotropic support

  • Uterine rupture: Immediate laparotomy, GA preferred for hemodynamic stability

  • Fetal compromise: Category 3 FHR, prepare for stat cesarean delivery

  • Maternal cardiac arrest: Perimortem cesarean within 4 minutes if >20 weeks

10. Post-Dural Puncture Headache (PDPH)

  • Prevention: 24-hour intrathecal catheter or epidural blood patch

  • Symptoms: Postural headache, neck stiffness, nausea, photophobia

  • Treatment: Bed rest, caffeine, blood patch if severe

  • Incidence: 16G needle 36%, 18G needle 6%, 25G pencil-point <1%

  • Timing: Usually within 48 hours, can be delayed up to 7 days

  • Blood patch technique: 15-20 mL autologous blood at same or adjacent level

  • Success rate: 85-90% after first blood patch, 95% after second

  • Conservative management: Adequate hydration, caffeine 300mg BD, simple analgesia

  • Differential diagnosis: Meningitis, subdural hematoma, cerebral venous thrombosis

11. Communication & Consent Challenges

  • Language barriers: Use translated resources (e.g., labourpains.org)

  • Emergencies: Clear, direct communication with surgeons (e.g., "Do not start until I confirm airway")

  • Informed consent elements: Risks, benefits, alternatives, failure rates

  • Documentation: Record consent process, patient understanding, questions answered

  • Capacity assessment: Especially important in labor, pain affects decision-making

  • Refusal management: Respect autonomy, document clearly, offer alternatives

  • Team communication: SBAR format, closed-loop communication

  • Handover protocols: Standardized format, include relevant contraindications

  • Cultural considerations: Religious beliefs, family involvement, modesty concerns

12. Paramedian Approach

  • Indications: Difficult anatomy (obesity, scoliosis), calcified ligaments

  • Technique: Needle angled 10–15° cephalad, lateral to spinous process

  • Entry point: 1-2 cm lateral to midline, one level below target interspace

  • Advantages: Avoids calcified interspinous ligament, wider target area

  • Disadvantages: More difficult to identify midline, risk of nerve root trauma

  • Success rate: Similar to midline approach in experienced hands

  • Learning curve: Requires more practice than midline technique

  • Complications: Increased risk of vascular puncture, nerve root contact

  • Ultrasound guidance: Particularly helpful for paramedian approach

13. Local Anesthetic Systemic Toxicity (LAST)

  • Signs: CNS (agitation, seizures) + CVS (arrhythmias, collapse)

  • Treatment: Stop injection, lipid emulsion (20% Intralipid), ACLS

  • Prevention: Aspiration before injection, incremental dosing, maximum dose limits

  • Early signs: Metallic taste, tinnitus, perioral numbness, agitation

  • Late signs: Seizures, cardiovascular collapse, cardiac arrest

  • Lipid emulsion dose: 1.5 mL/kg bolus, then 0.25 mL/kg/min infusion

  • Maximum LA doses: Lidocaine 5mg/kg, bupivacaine 2mg/kg (with adrenaline: 7mg/kg and 2.5mg/kg)

  • Risk factors: Pregnancy, extremes of age, cardiac disease, liver disease

  • Monitoring: Continuous ECG, frequent vital signs during and after injection

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