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David Yashon, Alfred P. Magness II, and W. Michael Vise

D eliberate induction of systemic hypotension is regarded as an intraoperative surgical adjunct with a limited and controversial application. Interest in hypotension persists since it allows conservation of blood volume and may provide a dry field for the operator. This technique has been used during prostatectomy, 94 correction of coarcted aorta, 38 radical mastectomy, 70 hysterectomy, 90 pelvic surgery, 8 ophthalmic surgery, 6 orthopedic surgery, 47 head and neck surgery, 87 and in neurosurgical procedures involving resection of vascular tumors

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Edward Tarlov, Henry Schmidek, R. Michael Scott, James G. Wepsic, and Robert G. Ojemann

W e have frequently seen hypotension with bradycardia and a low central venous pressure (CVP) in the early postoperative period following carotid endarterectomy for localized atheromatous disease at the carotid bifurcation. A fall in blood pressure poses a significant risk to these patients, among whom widespread occlusive arterial disease is common. One study of carotid sinus function after carotid endarterectomy has emphasized postoperative hypertension, 5 a phenomenon we rarely observed. Some authors state that endarterectomy does not alter baroreceptor

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A. Giancarlo Vishteh, Wouter I. Schievink, Jonathan J. Baskin, and Volker K. H. Sonntag

S pontaneous intracranial hypotension, as it has become understood more recently, is believed to be caused by cerebrospinal fluid (CSF) leakage from spinal meningeal diverticula or dural rents along nerve root sleeves. 2–8 These spinal CSF leaks are believed to evolve spontaneously, although a history of a trivial precipitating event often can be elicited. In many cases, such dural rents or meningeal diverticula cannot be identified on spinal myelography. The exact source of the leak still may not be identified intraoperatively even after extensive

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Francis W. Gamache Jr., Ronald E. Myers, and Esteban Monell

A lthough episodes of spontaneous or controlled hypotension are familiar to all clinicians, little is known about the changes that occur in the overall cerebral blood flow (CBF) or in the blood flow to specific brain regions either during or after such episodes. The local cerebral blood flow (L-CBF) refers to that which is distributed to individual neuroanatomic structures as compared to regional blood flow which is most commonly measured by determining the washout curves of gamma emitters detected by probes placed on the surface of poorly delimited, three

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David Yashon, George E. Locke, and William E. Hunt

S tagnant hypoxia resulting in anaerobic metabolism is an important factor in the pathophysiology of organ failure during sustained oligemic hypotension. 9 The failure of organ systems and the value of each in the scheme of bodily homeostasis is dependent on individual susceptibility to perfusion deficit and selective vulnerability of each organ in the sustenance of life processes. At the tissue level when substrate materials are depleted lactate accumulates as a result of conversion to anaerobic glucose metabolism. 18 Since glucose is the primary metabolite

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David Yashon, George E. Locke, W. George Bingham Jr., Wigbert C. Wiederholt, and William E. Hunt

have indicated preferential perfusion of the heart and brain during hypovolemia, at the expense of other organs. In the laboratory investigation of irreversible shock and oligemic hypotension, each somatic organ system has, at some time, been a source of interest, but few investigators have been specifically directed toward the central nervous system. In this report we have employed a model used frequently in the study of somatic systems in surgical shock, namely, a modified “Western Reserve” preparation described by Wiggers 21 and others. 11, 13, 15, 20 We have

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Richard L. Rovit

I mprovements in securing a dry field during intracranial vascular surgery have been based upon various combinations of hypotension and hypothermia. 3, 12, 19, 20, 21 Although moderate hypothermia is still being utilized today, enthusiasm for this method has waned over the past decade. We are describing our experience with a different and we believe better way of obtaining the advantages of hypotension through pace-maker-induced tachycardia. Historical Summary Profound Hypothermia with Circulatory Arrest In an effort to improve operative results in

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Alan A. Artru, Kim Wright, and Peter S. Colley

the degree used clinically adversely affects the brain. Both in animal studies and in man, hypocapnia at normal MABP causes no significant disturbance of cerebral metabolism and no reduction in the power of the electroencephalogram (EEG). 2, 14, 32, 36, 38, 44 Hyperventilation also may be used at times when MABP is not normal. For example, controlled hypotension is often induced during clipping of intracranial aneurysms subsequent to hyperventilating the patient. A recent study from this laboratory has reported that combining hypocapnia with hypotension causes

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Rudolf Laas, Bernd Jahn, and Kay Kessler

degree and duration of hypotension when other relevant parameters are kept close to normal levels. We used the experimental model described by Selkoe and Myers 20 with one difference: in order to avoid hypotensive cardiac failure, cephalic blood pressure was lowered not only by systemic hypotension but also by additional unilateral carotid ligation. Materials and Methods The 41 male albino rats (Chbb:THOM) used in this study had had free access to rat chow and tap water. Body weight ranged between 460 and 520 gm. The animals were anesthetized by intraperitoneal

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Naoki Ishige, Lawrence H. Pitts, Isabelle Berry, Merry C. Nishimura, and Thomas L. James

S hock is a frequent and important complication in severely head-injured patients, especially in the face of multiple injuries. 29 Neurological outcome after head injury without and with hypotension has been compared in humans 29, 35 and in animals. 32 Hypotension significantly increases the mortality rate. Changes in cerebral circulation and metabolism after head injury have been studied both experimentally 4, 9, 28, 37, 38, 51 and clinically, 6, 12, 39, 40 and autoregulation is impaired after traumatic head injury. 22, 51 Cerebral blood flow (CBF