Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Jul 2000
ReviewNeuroendoscopic procedures: anesthetic considerations for a growing trend: a review.
The recent trend in neurosurgery is shifting toward further reduction in invasiveness to minimize trauma to the brain. Endoscopy holds the promise of shortened hospital stay with improved postoperative outcome. An important minimally invasive technique is neuroendoscopy. ⋯ To date, there is paucity of anesthetic literature emphasizing the implications for this growing trend. The surgical technique, instrumentation, anesthetic requirements, potential pitfalls and complications of this technique must be completely understood to ensure a successful outcome. The purpose of this review is to provide knowledge of indications, instrumentation, and anesthetic considerations in anticipation of complications steming from this procedure.
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J Neurosurg Anesthesiol · Jul 2000
Cerebrovascular tone rather than intracranial pressure determines the effective downstream pressure of the cerebral circulation in the absence of intracranial hypertension.
Cerebral perfusion pressure is commonly calculated from the difference between mean arterial pressure and intracranial pressure because intracranial pressure is known to represent the effective downstream pressure of the cerebral circulation. Studies of other organs, however, have shown that effective downstream pressure is determined by a critical closing pressure located at the arteriolar level. This study was designed to investigate the effects of PCO2-induced variations in cerebrovascular tone on the effective downstream pressure of the cerebral circulation. ⋯ Our results demonstrate that, in the absence of intracranial hypertension, intracranial pressure does not necessarily represent the effective downstream pressure of the cerebral circulation. Instead, the tone of cerebral resistance vessels seems to determine effective downstream pressure. This suggests a modified model of the cerebral circulation based on the existence of two Starling resistors in a series connection.
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Fat embolism syndrome is a dire complication of long bone trauma. It is usually associated with neurological, hematological and respiratory involvement, the latter being the major cause of death. ⋯ The diagnosis was confirmed by cytology of the bronchoalveolar lavage fluid. Clinical presentation of the puzzling fat embolism syndrome and diagnostic tests in suspected fat embolism syndrome are reviewed.
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J Neurosurg Anesthesiol · Jul 2000
Case ReportsExaggerated hemodynamic responses to nasal injection and awakening from anesthesia in a Cushingoid patient having transsphenoidal hypophysectomy.
A 51-year-old female patient, with an adrenocorticotrophic hormone-secreting pituitary tumor, was scheduled for transphenoidal hypophysectomy. She had a history of recent onset diabetes mellitus and a 2-year history of arterial hypertension. Despite ongoing medical therapy, preoperative blood pressure was 150-160/90-120 mm Hg. ⋯ At the completion of the anesthetic, as the patient awakened and coughed and moved, blood pressure again increased dramatically, this time from 154/87 mm Hg to 285/170 over 3 minutes. Five months postoperatively, the patient's serum cortisol concentrations had normalized and her cuff blood pressure was 126/82, despite a reduction in her antihypertensive medications. The dramatic intraoperative blood pressure changes in this patient were attributed to the effects of hypercortisolemia on the normal physiologic responses to epinephrine and patient movement.
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J Neurosurg Anesthesiol · Apr 2000
Inhibitory effects of halothane, isoflurane, sevoflurane, and pentobarbital on the constriction induced by hypocapnia and bicarbonate in isolated canine cerebral arteries.
The effects of halothane, isoflurane, sevoflurane (0.5, 1 and 2 MAC) and pentobarbital (10(-5) M, 10(-4) M and 3 x 10(-4) M) on hypocapnia- and bicarbonate-induced constriction of isolated dog middle cerebral arteries were investigated in vitro. The isometric tension of isolated cerebral arterial rings was measured in an organ bath containing Krebs bicarbonate solution, aerated with 5% CO2 and 95% O2. Hypocapnia, induced by replacing the bathing solution with one that had been equilibrated with 2.5% CO2 and 97.5% O2, produced a sustained vasoconstriction (268 +/- 36 mg, mean +/- SEM). ⋯ Halothane (1 and 2 MAC) attenuated the constriction induced by hypocapnia to a greater extent than that induced by 15 mM KCl, whereas pentobarbital (10(-4) M and 3 x 10(-4) M) attenuated hypocapnia-induced constriction less than KCl-induced constriction. These results indicate that alkaline-induced constriction is more vulnerable to halothane than other volatile anesthetics and pentobarbital. The mechanisms of the inhibitory effects of halothane and pentobarbital on alkaline-induced cerebral vasoconstriction seem to differ; the inhibitory effect of pentobarbital, but not of halothane may be, in part, ascribed to its inhibitory effect on the Ca++ influx.