Etiologies

Etiologies

1. Catecholamine excess may be seen with inadequate anesthesia, especially during laryngoscopy, intubation, incision, emergence, hypoxia, hypercarbia, patient anxiety, pain, and prolonged tourniquet use.
2. Preexisting disease such as essential hypertension or pheochromocytoma.
3. Increased intracranial pressure
4. Systemic absorption of vasoconstrictors such as epinephrine and phenylephrine.
5. Aortic cross-clamping which leads to a significant increase in SVR.
6. Rebound hypertension from discontinuation of clonidine or β-adrenergic blockers.
7. Drug interactions. The administration of ephedrine to patients receiving tricyclic antidepressants (e.g., amitriptyline, nortriptyline, doxepin) and monoamine oxidase inhibitors (e.g., isoniazid, rasagiline, selegiline) may cause an exaggerated hypertensive response.
8. Bladder distention
9. Administration of indigo carmine dye (via an α-adrenergic effect).