THE HEMODYNAMIC EFFECT OF UNILATERAL CAROTID LIGATION ON THE CEREBRAL CIRCULATION OF MAN*

HENRY A. SHENKIN, M.D., FERNANDO CABIESES, M.D., GORDON VAN DEN NOORDT, M.D., PETER SAYERS, M.D., AND REUBEN COPPERMAN, M.A. Neurosurgical Service, Graduate Hospital, and Harrison Department of Surgical Re- search, Schools of Medicine, University of Pennsylvania, Philadelphia (Received for publication July ~5, 1950) HE increasing incidence of surgical attack upon vascular anomalies of the brain has renewed interest in the physiological responses of the T cerebral circulation to occlusion of a carotid vessel. This question has been studied in lower animals by Rein, 5 the Schneiders, 6 Bouckaert and Heymans 1 and by the late Cobb Pilcher. 4 However, because of the lack of an adequate technique for measuring the cerebral blood flow and because of the fact that lower animals have a rich intercommunication between the intracerebral and extracerebral circulations, very few data pertinent to human physiology have been accumulated. There are two important points to be established concerning carotid ligation: firstly, its therapeutic effect, that is the degree of fall of pressure in the vessels distal to the ligation, and secondly, its safety, determined by its effect on the cerebral blood flow. Sweet and Bennett, 8 by careful measurement of pressure changes distal to ligation, have provided informa- tion on the former point. It is the latter problem that is the subject of this paper. METHODS The subjects of this study were 4 patients with intracranial arterial aneurysms subjected to unilateral common carotid artery ligation. They ranged in age from 15 to 53 years (Table 1). The cerebral blood flow (CBF) was determined by means of the nitrous oxide technique s utilizing simul- taneous observations on blood from both internal jugular bulbs in each case just before and within 10 minutes after ligation of one common carotid artery in 3 of 4 patients. In 1 case (G. W.) the control study was done imme- diately preceding the carotid ligation, but subsequent observations were delayed until 4 days after carotid ligation, during which time no change in the clinical state of the patient was noted. The CBF was determined on the basis of blood from both internal jugu- lars because it had been previously found that two-thirds of the blood carried to the brain by one internal carotid artery was drained from the

* This investigation was supported in part by a research grant from the National Institutes of Health, Public Health Service. Presented in part at the meeting of the Harvey Cushing Society, Colorado Springs, Colorado, April 16, 1950. 38 HEMODYNAMIC EFFECT OF CAROTID LIGATION 39 brain by the homolateral internal jugular vein. 7 It was thought that perhaps changes in CBF might be detected after ligation, depending upon which internal jugular drainage was analyzed. The carbon dioxide and oxygen contents of the arterial and both jugular bloods were measured by the manometric technique of Van Slyke and Neill. 3 Mean arterial blood pressure (MABP) was obtained directly from the femoral artery by means of a damped mercury manometer. Cerebral oxygen consumption (CMRo2) was calculated from the formula CMRo2=CBF X[(A-V)oJl00] and the cerebrovascular resistance (CVR) was calculated from the formula CVR = MABP/CBF.

RESULTS There were no neurologic consequences of the carotid ligation in 3 of the 4 patients. In 1 patient (L. J.), the oldest in the series, within 8 minutes of ligation of the left common carotid artery, a right hemiplegia developed with loss of consciousness. The cerebral circulatory studies were started

TABLE 1 Effects of unilateral common carotid ligation on blood gas constituents

Blood CO~ Content Blood 02 Content (Vol. %) (Vol. %)

Arterial Int. Jugular Arterial Int. Jugular

C E C E C E C E

Pt. Age O L O L 0 L 0 L

S.P. 15 53.~ 5~.8 54.8 54. 11.~ 11.5 11.7 11.5

47.0 48.5 53.0 54.5 17.3 17.7 11.4 11.6

G.W. 18 51.~ 5~.5 55.3 55.0 1~.4 10.9 9.8 9.4

45.6 47.4 51.9 55.~ 18.5 17.~ 11.7 9.6

L.J. 53 58.~ 58.0 57.8 58.0 5.8 6.1 5.6 5.5

51.5 51.4 58.1 57.9 1~.8 1~.3 6.0 5.6

J.W. ~5 49.0 45.9 50.6 47.9 9.7 1~.9 8.6 11.3

43.~ 43.4 47.5 49.3 16.8 16.5 11.3 10.0

i Mean 5~.9 5~.3 54.6 53.8 9.8 10.4 8.9 9.4

~8 46.8 47.7 5~.6 54 .~ 16.3 15.9 10.1 9.2

C = Control observations. D = Observations following carotid ligation. O=Internal jugular on side of patent carotid. L = Internal jugular on side of ligated carotid.