Hypotension after neuraxial anesthesia: what are common causes and first-line treatments?

• A. A benign finding that requires no treatment.
• B. Myocardial infarction as the sole cause; treat with aspirin only.
• C. Hypovolemia due to blood loss; treat with fluids.
• D. Sympathetic blockade causing vasodilation; treat with IV isotonic fluids and vasopressors (phenylephrine or norepinephrine); assess block level and ensure adequate perfusion.

Answer: (D)

When hypotension follows neuraxial anesthesia, the most common mechanism is sympathetic blockade. Blocking the sympathetic nerves at the spinal level leads to vasodilation, especially of the venous capacitance vessels, causing pooling of blood, decreased venous return, and reduced systemic vascular resistance. The body’s perfusion suffers as a result.

The first-line management targets both restoring volume and increasing vascular tone. Administer IV isotonic fluids to augment preload and improve cardiac output, while using a vasopressor such as phenylephrine or norepinephrine to constrict vessels and raise arterial pressure. It’s also important to assess the extent of the block and ensure adequate perfusion to vital organs.

Other potential contributors, like hidden blood loss or myocardial ischemia, can occur but the initial, most common approach after neuraxial block centers on counteracting the vasodilatory effects of the block with fluids and vasopressors and verifying adequate perfusion.