Perioperative Hemodynamic Control - Induced Hypotension
Induced hypotension is a somewhat controversial technique used when control of bleeding improves operating conditions and facilitates surgical technique (e.g., middle ear microsurgery, cerebral aneurysm clipping, and plastic surgery) or reduces the need for transfusion (e.g., orthopedic surgery, patients with rare blood groups, and religious constraints). An acceptable blood pressure goal is a target MAP of 30% below a patient's baseline, with a MAP no lower than 50 mm Hg in an otherwise healthy patient and 80 mm Hg in an elderly patient. This technique is not appropriate for patients with a history of vascular insufficiency to the heart, brain, or kidneys; cardiac instability (unless afterload reduction improves performance); uncontrolled hypertension; anemia; or hypovolemia. It should be utilized with caution as serious complications, while rare in healthy patients, include cerebral infarct, myocardial infarction, and acute kidney injury. Hypotension can be achieved using neuraxial blockade, high concentrations of volatile anesthetics, potent short-acting opioids (e.g., remifentanil), and peripheral vasodilators (e.g., nitroprusside or nitroglycerin). While this technique was first described in the 1940s and gained widespread popularity over the past 40 years, there is a paucity of data to support or refute this hemodynamic technique as efficacious.
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