Hyperperfusion syndrome after carotid endarterectomy

I would like to share the protocol for treatment of hyperperfusion syndrome after carotid endarterectomy. This protocol was developed on the Vascular Surgery Service at Maimonides Medical Center, Brooklyn, New York. Hyperperfusion sometimes occurs after revascularization. Swelling apart from that caused by the surgical procedure occurs as a result of newly established blood flow to tissues previously compromised by stenotic lesions. In the lower extremities, this can cause swelling and erythema. In the cranial vault, this can cause cerebral edema, increased intracranial pressure, seizures, and stroke. In the setting of carotid endarterectomy, patients with volume flow rate 200 cc/min at completion duplex bilateral severe carotid stenosis appear to be at greater risk for this to occur. In addition, some patients have very high opening pressures during the carotid endarterectomy procedure, placing them at risk for hyperperfusion. The Vascular Surgery Service has found that such patients require treatment of hyperperfusion syndrome to reduce their postoperative risk of stroke and seizure. The treatment protocol developed by the Vascular Surgery Service involved administration of hydrocortisone and phenytoin to reduce the effects of swelling and cerebral edema and decrease the risk of seizures. To reduce the risk of gastric irritation or gastric ulcer, an H2 blocker is administered to suppress hydrochloric acid production and raise the pH of the stomach. These agents are administered over a 30-day period, as described below. On this vascular service, most of the patients are discharged the day after their carotid endarterectomy. The protocol is implemented in 2 parts. In part 1, during the immediate postoperative period after the carotid endarterectomy, intravenous therapy is initiated in the recovery room by the surgeon (Table 1). When the patient returns to the surgical unit, the vascular nurse practitioner ensures placement in the medical record of a copy of the preoperative carotid duplex depicting severe bilateral stenosis. The intravenous route is used until the patient can tolerate an oral intake. This usually results in the patient’s having received 4 to 6 doses intravenously. In part two, when the patient can tolerate food and medicine by mouth, the vascular nurse or the surgical resident continues orders for these medicines, converting them to oral doses. Prescriptions are prepared for the patient upon discharge. In addition, the hydrocortisone is converted to a prednisone taper regimen, as noted in Table 1. Specific prednisone doses per day are depicted in Table 1. During the hospitalization, the patient is instructed by the vascular nurse practitioner or surgical resident about the precautionary need for this treatment plan (Table 2). The patient is taught by the vascular nurse about side effects. For a short course of phenytoin therapy, side effects include lethargy, abnormal movement, mental confusion, and cognitive changes. At toxic levels, phenytoin can cause ataxia, nystagmus, dysarthria, encephalopathy, slurred speech, and a rash. The patient is advised that the physician will need to monitor blood levels of Dilantin. Weekly Dilantin levels may be ordered for the duration of therapy. It is usually well tolerated, highly effective, and relatively inexpensive. Patients should avoid driving or engaging in other activities that require alertness when taking any anticonvulsants. All the systematically administered glucocorticoids have a similar clinical efficacy but differ in their potency and duration of action and in the extent to which they cause salt and fluid retention. The effects of hydrocortisone can influence every body system, with the result that they can produce a wide variety of significant undesirable effects. The more common of these include headache, vertigo, congestive heart failure, hypertension, carbohydrate intolerance, hyperglycemia, peptic ulcers, abdominal distention, fragile skin, petechiae, ecchymoses, and muscle weakness. A careful explanation about the tapering of the steroid is emphasized (Table 2). The vascular nurse instructs patients to avoid abrupt cessation and to continue the tapering as directed. The H2 blockers have a remarkably low incidence of side effects. The more common of these include headache, confusion, lethargy, abdominal cramps, diarrhea, sweating, and flushing. Famotidine has essentially no effect on binding the hematic cytochrome P-450 microsomal oxidase system. Thus, famotidine has little potential to raise the blood concentration of drugs that are metabolized by the liver with this enzyme system (eg, phenytoin, warfarin, and theophylline). From Medgar Evers College, New York, New York.