A 35-year-old primigravida receives an epidural for labor analgesia. Shortly after the bolus dose, she develops sudden profound hypotension, bradycardia, and difficulty breathing, followed by loss of consciousness. Which of the following is the most likely complication?

Explanation

Total spinal anesthesia occurs when a large dose of local anesthetic intended for the epidural space is inadvertently injected into the subarachnoid space. This results in widespread sympathetic blockade (profound hypotension, bradycardia) and motor/sensory blockade extending up to the brainstem, leading to respiratory depression and loss of consciousness. Epidural hematoma typically presents later with neurological deficits. Post-dural puncture headache is a headache that develops after dural puncture, usually hours to days later. Local anesthetic systemic toxicity (LAST) presents with CNS symptoms (e.g., seizures) and cardiovascular collapse, but the rapid onset of widespread motor/sensory blockade and respiratory compromise points more strongly to total spinal anesthesia in this context.