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Biomedical subjects

D O Quest

Publications and source records attributed to D O Quest.

At least 19 recordsLinked to original sources
PubMed1991

A comparison of cerebral blood flow reactivity to CO2 during halothane versus isoflurane anesthesia for carotid endarterectomy.

The effects of isoflurane or halothane on cerebral blood flow (CBF) reactivity to changes in arterial carbon dioxide tension (PaCO2) during carotid endarterectomy were compared using the intravenous method of 133Xe-CBF determination. Patients, aged 65 +/- 3 yr (mean +/- SE), received O2 and N2O (1:1) and either 0.75% isoflurane (n = 7) or 0.5% halothane (n = 7). Patient demographic and clinical data were similar for both groups and followed the expected strata of patients with ischemic cerebrovascular disease. Measurements were made during the period of temporary bypass shunting. In the isoflurane group, increasing PaCO2 from 33.3 +/- 1.4 to 43.4 +/- 1.3 mm Hg resulted in a significant (P less than 0.05) increase in CBF from 21 +/- 1 to 35 +/- 4 mL.100 g-1.min-1. In the halothane group, increasing PaCO2 from 31.1 +/- 1 to 39.4 +/- 1.6 mm Hg resulted in a significant increase in CBF from 26 +/- 3 to 37 +/- 3 mL.100 g-1.min-1. Mean CBF reactivity to changes in PaCO2 (mL.100 g-1.min-1.mm Hg-1) was 1.74 +/- 0.39 for isoflurane and 1.78 +/- 0.4 for halothane (not significant), corresponding to a relative change of 4.8% +/- 0.8% and 5.2% +/- 1.3% per mm Hg, respectively. There is no significant difference between halothane and isoflurane in their effects on CO2 reactivity in the mildly hypocapnic to normocapnic range.

Aged↗
PubMed1989

Cerebral revascularization: a review.

A review of the development and current methods of surgical revascularization of the cerebral circulation is presented. In addition to the conventional superficial temporal artery to middle cerebral artery (STA-MCA) bypass, the techniques of interposition vein grafting and vertebrobasilar revascularization are discussed. The results and implications of the International Cooperative Study are reviewed. Extracranial-intracranial (EC-IC) bypass grafting remains an essential procedure in the treatment of many cerebrovascular conditions, including Moya Moya disease and giant intracranial aneurysms. The efficacy of interposition vein grafts, as well as the EC-IC bypass in the treatment of vertebrobasilar insufficiency, acute cerebral ischemia, cerebral vasospasm, and multi-infarct dementia, remains to be determined. Several alternative revascularization procedures, including proximal MCA anastomosis and omental transposition, are in development.

Brain Diseases↗
PubMed1988

Electroencephalographic monitoring for ischemia during carotid endarterectomy: visual versus computer analysis.

In a retrospective study, we compared the use of computer-generated spectral electroencephalographic descriptors with a neurologist's interpretation of raw EEG data. Data were collected from patients undergoing carotid endarterectomy and anesthetized with isoflurane in nitrous oxide and oxygen. The EEG was recorded on magnetic tape during the period immediately before and after occlusion. These tapes were then analyzed off-line using a computer to generate averaged changes in 18 spectral descriptors. A strip-chart of raw EEG before and after the carotid occlusion was interpreted by a neurologist, who assigned changes in the EEG following occlusion to one of four visual inspection groups, depending on the severity of change. A descriptive examination of the distribution of changes in spectral descriptors revealed that no single descriptor adequately reflected the neurologist's interpretation of the raw EEG. Using data from 20 patients, the percent change from preocclusion to postocclusion values for total power, spectral edge frequency, spectral variance, and log spectral variance was examined. Only for the visual inspection group judged by the electroencephalographer to have the most severe ischemic change was there a significant difference in total power and log spectral variance. Although computer-processed EEG devices are of value as trending devices for detecting visual patterns associated with inadequate cerebral perfusion, single descriptors in this study did not consistently reflect a neurologist's diagnosis of ischemia. Single descriptors of spectral EEG analysis may not be sufficient to use as alarm variables in the recognition of cerebral ischemia.

Brain Ischemia↗
PubMed1988

Reduced hypercapnic vasoreactivity in moyamoya disease.

We measured cerebral perfusion at rest and in response to CO2 in eight patients with moyamoya disease (MMD), using the 133xenon inhalation method to determine the effect of large-vessel occlusive disease on vasoreactivity. We studied three other groups for comparison, including four with bilateral internal carotid artery occlusions (BICAO), 11 with unilateral carotid occlusion (UICAO), and six with unilateral middle cerebral artery stem occlusion (UMCAO). Resting flows appeared to correlate with the severity of occlusive disease overall. Normocapnic perfusion was lowest in the group with BICAO and decreased in proportion to the degree of contralateral stenosis in the group with UICAO. Hypercapnic perfusion correlated with the apparent adequacy of angiographic collaterals. Reactivity was lowest in the MMD group (0.79%/mm Hg) whose collateral supply was limited to leptomeningeal anastomosis from the posterior cerebral artery, but highest in the patients with BICAO (2.72%/mm Hg), each of whom showed excellent posterior communicating artery flow. The clinical course of the MMD group was compatible with the syndrome of perfusion insufficiency with repeated ischemic attacks or a saltatory progression of an ischemic deficit; CT showed infarction in the borderzone territory. These results suggest that a severely reduced hypercapnic response may help to identify patients with ischemic syndromes due to perfusion failure in the borderzones, as in MMD.

Adult↗
PubMed1987

Technical controversies in carotid artery surgery.

Carotid endarterectomy has become a routine and safe therapeutic strategy in most neurovascular centers. Wide diversity of opinion and considerable debate, however, persists concerning the ideal methods of anesthetic management, cerebral protection, intraoperative monitoring, and arterial repair. We have examined and summarized the current status of these controversies and have identified several new techniques that hold promise for further development.

Anesthesia↗
PubMed1987

Neurotrauma care and the neurosurgeon: a statement from the Joint Section on Trauma of the AANS and CNS.

The AANS and CNS support the concept of organized neurosurgical trauma care consisting of the appropriate combination of prepared communities and institutions and of adequate numbers of committed neurosurgeons. Furthermore, we support the guidelines of the ACS regarding institutions designated to receive trauma patients, and support the concept of prehospital triage of trauma victims based upon well-trained EMS personnel guided by criteria selected by the local neurosurgical community. We support audit systems that include neurosurgeons to assess and improve the quality of neurotrauma care. By using the principles outlined above, neurosurgeons can plan, support, and evaluate whatever system their community or region requires for the optimal care of the neurotrauma patient.

Health Planning Guidelines↗
PubMed1987

Carotid endarterectomy for stroke prevention.

Minor neurologic signs or transient ischemic attacks (TIAs) precede stroke in 50 percent of patients. In men, antiplatelet therapy decreases the risk of recurrent TIA and stroke. Carotid endarterectomy for TIA is now one of the most commonly performed vascular operations. Preoperatively, the arterial anatomy of the patient must be carefully studied by conventional angiography or digital subtraction angiography. The goal of surgery is to eliminate the atherosclerotic plaque and restore the artery to its normal size with a smooth intima.

Anticoagulants↗
PubMed1986

Incidence and etiology of intracerebral hemorrhage following carotid endarterectomy.

In a consecutive series of 1930 carotid endarterectomies there were eight cases of postoperative intracerebral hemorrhage. One of these patients was operated on 2 weeks following cerebral infarction and had severe uncontrollable hypertension after surgery. A second patient had an intraoperative embolus and bled while fully heparinized on the 3rd postoperative day. Only one patient in the series bled into an area of documented cerebral infarction. The remainder of the cases represented hemorrhage into essentially normal brain. Seven of the eight patients with intracerebral hemorrhage had high-grade internal carotid artery stenosis preoperatively. Although several factors have contributed to the brain hemorrhages in this series of patients, postoperative cerebral hyperperfusion which often follows endarterectomy may have played an important role. Defective cerebrovascular autoregulation in chronically ischemic brain regions may predispose patients to intracerebral hemorrhage after removal of a high-grade stenosis of the internal carotid artery.

Aged↗
PubMed1979

Artificial vision for the blind by electrical stimulation of the visual cortex.

Artificial vision for the blind may be feasible by interfacing a television camera with electronics stimulating the visual cortex. The status of a major collaborative effort involving the College of Physicians and Surgeons of Columbia University, the University of Utah, and the University of Western Ontario is reviewed. Results have been very encouraging, although much work remains to be done.

Blindness↗
PubMed1978

Period of risk for recurrence in medulloblastoma.

Ninety-nine patients with medulloblastoma who received surgery and radiotherapy, and had a statistically sufficient follow-up period were analyzed for factors influencing survival and the relevance of the "period of risk for recurrence" hypothesis. This postulate states that the period of risk for recurrence of a congenital tumor is equal to the age at presentation of illness plus 9 months' gestational time. The assumption is made that a tumor of embryonic origin will become manifest after a period of time determined by its inherent rate of growth and that tumor cells surviving treatment will multiply and present with recurrence in an equal period of time. Ten of 43 patients survived the period of risk, a presumed cure rate of 23%. None of these patients has subsequently developed evidence of tumor recurrence. Older patients at initial surgery had a somewhat greater survival rate for the first 5 years after treatment (10 of 26 older patients (38%) versus 15 of 54 younger patients (28%)), but by 10 years there was no appreciable difference in survival rates between those over 16 years of age and those younger. The beneficial effect of total neuraxis megavoltage radiotherapy is indicated by the improved 5-year survival rate from 9 of 41 patients (22%) to 16 of 39 patients (41%) with the newer techniques.

Adolescent↗