Spinal (intrathecal) anaesthesia

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Target exams

Red flags

• Hypotension after spinal anaesthesia reflects the sympathetic block and can be profound, especially in the obstetric or volume-depleted patient; anticipate it with vasopressor and a colloid co-load and treat early and proactively.
• A rising block above the fourth thoracic dermatome produces bradycardia, hypotension and respiratory compromise — a high spinal; support the circulation and ventilation until the block recedes.
• A postural headache worse on standing and relieved by lying flat after a dural puncture is a post-dural puncture headache until proven otherwise; a fine pencil-point needle and a single dural puncture reduce its incidence.
• Severe back pain with a new and progressive neurological deficit after a spinal is an epidural haematoma or abscess until proven otherwise; it is a surgical emergency demanding urgent imaging and decompression.
• Profound bradycardia or asystole shortly after a high spinal in a young, fit, hypovolaemic or obstetric patient may be the Bezold-Jarisch reflex; treat with vasopressor, fluid and atropine and avoid the head-up position.
• Coagulopathy, therapeutic anticoagulation outside the recommended intervals, infection at the puncture site and patient refusal are the principal contraindications; in the anticoagulated obstetric patient the SOAP consensus guides timing.