Journal of neurosurgical anesthesiology
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Near-infrared spectroscopy is a technique used to monitor cerebral oxygenation. To validate the method, we measured regional oxygen saturation (rSo2) in the brains of 18 dead subjects (mean age, 74.4 +/- 14.6 years) 19.8 +/- 18.2 h (range, 1-73) after cessation of systemic circulation, and in 15 healthy probands (mean age, 34.2 +/- 8.7 years) with an INVOS 3100 cerebral oximeter. The mean (+/-SD) rSo2 in the dead subjects was 51.0 +/- 26.8% [range, 6-88%; left, 48.4 +/- 28.0% (n = 21); right, 54.4 +/- 25.7% (n = 16)]. ⋯ After removal of the brain at autopsy in five of the dead subjects, the rSo2 was 73.4 +/- 13.3% (15 measurements). Six of 18 of the dead subjects had values above the lowest values found in the healthy adults (> or = 60%). These findings raise concerns about the validity of cerebral rSo2 data in adults obtained by the INVOS 3100 system.
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J Neurosurg Anesthesiol · Jul 1996
Comparative StudyChanges in cerebral blood flow velocity in children during sevoflurane and halothane anesthesia.
The purpose of this study was to evaluate arterial blood pressure and middle cerebral artery blood flow velocity in children during induction of anesthesia with sevoflurane. These measures were compared to findings in a control group anesthetized with halothane. Each child received mask induction of sevoflurane (n = 9) or halothane (n = 9) with 70% nitrous oxide in oxygen. ⋯ Both sevoflurane (2.4%) and halothane (1.3%) combined with 70% nitrous oxide decreased blood pressure and increased cerebral blood flow velocity. Intubation increased blood pressure and further increased cerebral blood flow velocity with both anesthetic treatments. These results indicate that sevoflurane and halothane combined with nitrous oxide decrease blood pressure and increase cerebral blood flow velocity and suggest that sevoflurane produces cerebrovascular effects similar to those of halothane during anesthetic induction.
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J Neurosurg Anesthesiol · Jul 1996
Case ReportsContinuous postoperative lCBF monitoring in aneurysmal SAH patients using a combined ICP-laser Doppler fiberoptic probe.
Cerebral vasospasm remains the principal cause of morbidity and mortality following successful clipping of intracranial aneurysms. Current management often requires subjective judgments concerning presumed abnormalities of cerebral blood flow. In this study, a combined intracranial pressure (ICP)-laser Doppler flowmetry (LDF) fiberoptic probe that permits continuous monitoring of local cerebral blood flow (lCBF) was used in the postoperative management of 20 aneurysm patients. ⋯ The combined probe also provided the ability to obtain precise and detailed information concerning the presence or absence of cerebral autoregulation and CO2 vascular reactivity, and allowed calculation of the cerebral vascular resistance. Continuous monitoring of lCBF in this manner complemented by transcranial Doppler and angiographic data permitted early detection of cerebral ischemia, helped to differentiate cerebral ischemia from edema and hyperemia, was useful in titrating blood pressure and fluid management, provided direct feedback about the effectiveness of instituted therapies, and determined early on when medical management was of no avail and that interventional neuroradiology was indicated. Evidence is presented that the presence of angiographic vasospasm and increased velocities on TCD do not always correlate with ischemia in the microcirculation and that direct measurements of lCBF are often at variance with calculations of cerebral perfusion pressure (CPP).
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J Neurosurg Anesthesiol · Apr 1996
Case ReportsPositioning a right atrial air aspiration catheter using transesophageal echocardiography.
The occurrence of venous air embolism (VAE) during neurosurgery in the sitting position is well documented. The optimal position of an air aspiration catheter appears to be with the catheter tip at the junction of the right atrium and superior vena cava (SVC). A number of localization techniques have been described, with the electrocardiographic guided technique being the most commonly employed. This case report describes the use of transesophageal echocardiography (TEE) for the precise and timely placement of a right atrial-SVC air aspiration catheter.
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J Neurosurg Anesthesiol · Apr 1996
Clinical TrialBrain relaxation and cerebrospinal fluid pressure during craniotomy for resection of supratentorial mass lesions.
Neurosurgery can be complicated by the clinical situation commonly referred to as "tight brain," in which the brain presses against the inner table of the skull or protrudes through the craniotomy site. We report here a retrospective study of 32 patients who had undergone elective craniotomy for resection of supratentorial mass lesions. We determined the relationship between lumbar cerebrospinal fluid pressure (CSFP) and brain relaxation and whether brain relaxation varies with anesthetic technique. ⋯ We conclude that in patients undergoing elective craniotomy for resection of a supratentorial mass lesion, brain relaxation is not predictive of CSFP. Although CSFP values at the extremes of the observed distribution ( > 17 mm Hg or < 6 mm Hg) did correlate with brain relaxation, within the range of 6-17 mm Hg, CSFP did not predict brain relaxation. Additionally, the data from this study suggest that in patients undergoing elective craniotomy for resection of a supratentorial mass lesion, tight brain may occur with a lower frequency in patients receiving 0.5 MAC ISO or DES with 50% N2O than in patients receiving 1 MAC ISO or DES.