During epidural anaesthesia for labour, the patient suddenly develops hypotension, bradycardia, loss of consciousness, and bilateral arm weakness 20 minutes after top-up with 15 mL of 0.5% bupivacaine. The MOST likely cause is:
- A Aortocaval compression causing sudden supine hypotension
- B Total spinal block from unintentional intrathecal injection of the epidural dose ✓
- C Systemic local anaesthetic toxicity from inadvertent intravascular injection
- D Hypersensitivity reaction to bupivacaine preservative (methylparaben)
Explanation
High or total spinal block occurs when an epidural dose (designed for the epidural space) is accidentally injected intrathecally. Bupivacaine 0.5% in a 15 mL volume vastly exceeds any spinal dose, producing rapid ascent of blockade to cervical levels. Clinical features include profound hypotension from sympathectomy, bradycardia (cardiac accelerator fibre blockade at T1–T4), respiratory failure, and arm weakness or paralysis as cervical motor roots are blocked. Systemic toxicity (option C) typically presents with CNS excitation (seizures) before cardiovascular collapse, and onset would be faster (1–3 minutes post-injection).
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.