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Departments of *Anesthesiology,
Radiology,
Neurology, and ¶Neurological Surgery and the
Institute of Comparative Medicine, College of Physicians and Surgeons of Columbia University, New York, New York; and ||Departments of Anesthesiology, Neurology, and Neurosurgery, University of California, San Francisco, California
Address correspondence to Shailendra Joshi, MD, Department of Anesthesiology, P&S P Box 46, College of Physicians and Surgeons of Columbia University, 630 W. 168th St., New York, NY 10032. Address e-mail to sj121{at}columbia.edu No reprints will be available.
Intracarotid infusion of short-acting vasodilators, such as adenosine and nitroprusside, in doses that lack significant systemic side effects, may permit controlled manipulation of cerebrovascular resistance. In this experiment we assessed changes in cerebral blood flow (CBF) after intracarotid infusion of nitroprusside and adenosine. The study was conducted on six adult baboons under isoflurane anesthesia and controlled ventilation. Intracarotid drug infusion protocol avoided hypotension during nitroprusside infusion and tested for autoregulatory vasoconstriction. CBF (intraarterial 133Xe technique) was measured four times during infusions of 1) intracarotid saline, 2) IV phenylephrine (0.2 µg · kg-1 · min-1) aimed to increase mean arterial pressure by 1015 mm Hg, 3) IV phenylephrine and intracarotid nitroprusside (0.5 µg · kg-1 · min-1), and 4) intracarotid adenosine (1 mg/min). IV phenylephrine increased mean arterial pressure (69 ± 8 to 91 ± 9 mm Hg, P < 0.0001, n = 6), and concurrent infusion of intracarotid nitroprusside reversed this effect. However, compared with baseline, CBF did not change with IV phenylephrine or with concurrent infusion of IV phenylephrine and intracarotid nitroprusside. Intracarotid adenosine profoundly increased CBF (from 29 ± 8 to 75 ± 32 mL · 100 g-1 · min-1; P < 0.0001). In nonhuman primates, intracarotid adenosine increases CBF in doses that lack significant systemic side effects, whereas intracarotid nitroprusside has no effect. Intracarotid adenosine may be useful for manipulating cerebrovascular resistance and augmenting CBF during cerebral ischemia.
IMPLICATIONS: Intraarterial 133Xe cerebral blood flow (CBF) measurements suggest that intracarotid adenosine, in a dose that lacks significant systemic side effects, profoundly increases CBF, whereas nitroprusside has no effect.(512)
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