Clinical Case for Discussion: A 74-year-old man is scheduled for a left carotid endarterectomy. At the conclusion of the anesthetic, his blood pressure rises to a Mean Arterial Pressure (MAP) of 110, and he is unable to move the right side of his body. What do you do?
Discussion: In 19 years of doing vascular anesthesia, I had this happen to my patient two times. The first time it occurred, I wasn’t sure what to do, if anything, about the new neurologic deficits.
Let us assume that you already carried out the textbook approach to anesthesia for carotid thromboendarterectomy (TEA) for this patient. All appropriate diagnostic and therapeutic measures were done to prepare the patient for surgery. His preoperative MAP was 100. During the general anesthetic the MAP was maintained between 90 and 110. The surgeon used a carotid shunt, and during clamping and shunting no hypotension occurred. (These were the circumstances in both the post operative strokes in my patients.) At the conclusion of surgery, you discontinued the anesthetics, and the blood pressure increased as the anesthetic depth lightened. The MAP increased to 110. You extubated the patient awake. Then you noticed that the right leg and arm were not moving. The surgeon returned to the bedside, and said, “I need him back asleep, as fast as possible!”
What do you do at this point? You give additional doses of anesthetic and relaxant, and reintubate the trachea. You may be feeling guilty, wondering if this paralysis is an anesthetic complication. What the surgeon is thinking is, “do I have a diagnosis that I can treat, such as a dissection, a flap, or a clotted carotid artery?” The surgeon may ask you to give a repeat dose of heparin to the patient. After a quick prep and drape, he reopens the skin incision. The surgeon assesses the pulse in the carotid, and may do a Doppler ultrasound exam. Next is an on-the-table angiogram, which shows that both the common and internal carotid arteries are 100% occluded.
The surgeon closes the wound. You discuss the plan with the surgeon. The plan is to keep the trachea intubated to protect the airway. You discontinue the general anesthesia, and substitute a propofol infusion for transport to the ICU.
Per Miller’s Anesthesia, 5th edition, 2000, p 1878, “for carotid endarterectomy, most centers report a perioperative stroke rate of between 3 and 5 per cent. The incidence of perioperative stroke is highest for patients with stroke, lower for patients with transient ischemic attack, and lowest in asymptomatic patients. Neurologic deficits occur most commonly in patients with poorly controlled preoperative hypertension or in those with hypertension or hypotension postoperatively. More than half of these deficits occur more than 4 hours postoperatively.”
If you do hundreds of carotid TEA’s during your career, a non-zero number of patients will have postoperative strokes. As the anesthesiologist, you have control of the patient’s blood pressure and heart rate. Extremes of blood pressure that are outside the range of autoregulation of cerebral perfusion can contribute to cerebral ischemia. But most strokes will be surgical complications. Per Sabiston, (Textbook of Surgery, 2001, p 1348), “neurologic deficits within the first 12 hours of operation are almost always the result of thromboembolic phenomena stemming from the endarterectomy site or damaged internal, common, or external carotid arteries.”
I learned from my experiences not to extubate the carotid TEA patient until he proves he is awake and can move the contralateral extremities. If there is a stroke, you need only to give more drugs to resume anesthesia, instead of the risks of repeat laryngoscopy and intubation as in the case above.
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Nuanced characterization and crafty details help this debut soar.
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