Journal of neurosurgical anesthesiology
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This review assesses the extent to which sevoflurane fulfills the requirements of the ideal inhalational agent for use in neuroanesthetic practice. Sevoflurane's pharmacokinetic profile is outlined. ⋯ Where possible, sevoflurane is compared with isoflurane, currently considered the inhalational agent of choice in neuroanesthesia. Sevoflurane's potential for toxicity is reviewed.
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J Neurosurg Anesthesiol · Apr 2000
The influence of positioning on spectroscopic measurements of brain oxygenation.
This study was designed to evaluate the influence of body position during neurosurgical and cerebrovascular operations on regional cerebral oxygen saturation (rSO2). Awake volunteers (group I; n = 14), anesthetized patients (group II; n = 48) undergoing lumbar discectomy, and 12 patients undergoing carotid endarterectomy (group III) with internal carotid artery (ICA) stenosis were studied. Anesthesia in the patient groups was performed with sevoflurane (1.1 Vol% insp.) in N2O2/O2 mixture (FiO2 0.4) rSO2 was monitored with a INVOS 4100 cerebral oxymeter (Somanetics Corporation, Troy, MI). ⋯ After turning the head to the ipsilateral side, this difference diminished. In contrast, turning the head toward the contralateral side, the rSO2 difference remained nearly constant, both values decreasing constantly throughout the observation period. In conclusion, after different positioning maneuvers awake and under anesthesia, alterations of rSO2 can be registrated by near-infrared spectroscopy (NIRS).
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J Neurosurg Anesthesiol · Apr 2000
Case ReportsAntecubital central venous catheter placement complicated by a persistent left superior vena cava.
A 14-year-old female in whom we encountered a persistent left superior vena cava during placement of a central venous catheter is presented. The patient had a history of coarctation of the aorta, but the left superior vena cava was unknown. Since the incidence of persistent left superior vena cava in patients with congenital heart disease is ten times as great as those without, in this patient population it may be useful to obtain radiographic confirmation of catheter position before use.
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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.
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J Neurosurg Anesthesiol · Apr 2000
The use of hyperventilation in the treatment of plateau waves in two patients with severe traumatic brain injury: contrasting effects on cerebral oxygenation.
We present the case reports of two patients with severe traumatic brain injury who, in the absence of external stimuli, developed episodes of acute elevation of intracranial pressure (plateau waves) associated with jugular bulb oxyhemoglobin (SjO2) desaturation, severe reduction of cerebral tissue PO2 (PbrO2), and deterioration of neurological status. In all of these episodes hyperventilation was successful in extinguishing plateau waves, but in one patient it was associated with an improvement of both the global (increased SjO2) and local (increased PbrO2) cerebral perfusion, while in the other patient it was associated with a reduction of both SjO2 and PbrO2. In both patients the effects of hyperventilation (and other pharmacological treatments) were short-lived; plateau waves reappeared and the patients had to be submitted to decompressive craniotomy (first patient) and cerebrospinal fluid (CSF) drainage (second patient). We conclude that hyperventilation can be useful as a temporary measure to treat plateau waves, but cerebral oxygenation should always be monitored to avoid iatrogenic cerebral ischemia.