Regional cerebral blood flow and glucose metabolism during propofol anaesthesia in healthy subjects studied with positron emission tomography.

Background: General anaesthetics can alter the relationship between regional cerebral glucose metabolism rate (rGMR) and regional cerebral blood flow (rCBF). With the present study, we wanted to assess quantitatively the effects of propofol on rCBF and rGMR in the same healthy volunteers measured with positron emission tomography (PET).

Methods: (15)O-labelled water and (18)F fluorodeoxyglucose were used as PET tracers to determine rCBF and rGMR, respectively, in eight healthy volunteers during the waking state (baseline) and during propofol anaesthesia.

Regional cerebral glucose metabolism during sevoflurane anaesthesia in healthy subjects studied with positron emission tomography.

Background: The precise mechanism by which sevoflurane exerts its effects in the human brain remains unknown. In the present study, we quantified the effects of sevoflurane on regional cerebral glucose metabolism (rGMR) in the human brain measured with positron emission tomography.

Methods: Eight volunteers underwent two dynamic 18F-fluorodeoxyglucose positron emission tomography (PET) scans.

Regional cerebral blood flow responses to hyperventilation during sevoflurane anaesthesia studied with PET.

Background: Arterial carbon dioxide tension (PaCO(2)) is an important factor controlling cerebral blood flow (CBF) in neurosurgical patients. It is still unclear whether the hypocapnia-induced decrease in CBF is a general effect on the brain or rather linked to specific brain regions. We evaluated the effects of hyperventilation on regional cerebral blood flow (rCBF) in healthy volunteers during sevoflurane anaesthesia measured with positron emission tomography (PET).

Cerebral blood flow, blood volume, and mean transit time responses to propofol and indomethacin in peritumor and contralateral brain regions: perioperative perfusion-weighted magnetic resonance imaging in patients with brain tumors.

Background: The regional cerebral blood flow (CBF) response to propofol and indomethacin may be abnormal in patients with brain tumors. First, the authors tested the hypothesis that during propofol anesthesia alone and combined with indomethacin, changes in CBF, cerebral blood volume (CBV), and plasma mean transit time (MTT) differ in the peritumoral tissue compared with the contralateral normal brain region. Second, the authors tested the hypothesis that CBF and CBV are reduced and MTT is prolonged, in both regions during propofol anesthesia and indomethacin administration compared with propofol alone.

The relationship between intracranial pressure and the degree of brain swelling in patients subjected to infratentorial surgery.

Background: In patients with supratentorial tumours, intracranial pressure is a strong predictor of intra-operative brain swelling and thresholds for ICP associated with brain swelling have been defined. Whether these ICP thresholds can be applied during infratentorial surgery is uncertain. We studied the relationship between subdural ICP and the degree of brain swelling after opening of the dura mater in patients subjected to infratentorial surgery.

Pharmacokinetics and pharmacodynamics of indomethacin: effects on cerebral blood flow in anaesthetized sheep.

1. Indomethacin has been used to manage raised intracranial pressure (ICP) in humans during neuroanaesthesia and neurosurgery. Indomethacin causes cerebral vasoconstriction and reduces cerebral blood flow (CBF) and, therefore, ICP.

Optimal reverse trendelenburg position in patients undergoing craniotomy for cerebral tumors.

Object: To the authors' knowledge, repeated measurements of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and the degree of dural tension during different positions on the operating table (reverse Trendelenburg position [rTp]) have not been studied in patients undergoing craniotomy.

Methods: In the present study 53 patients with supratentorial cerebral tumors who underwent craniotomy in the supine position were included. Subdural ICP, mean arterial blood pressure (MABP), CPP, and jugular bulb (JB) pressure were recorded, and the degree of dural tension was analyzed while patients were in the neutral operating position and at 5, 10, and 15 degrees rTp.

Acupuncture of LI-4 in anesthetized healthy humans decreases cerebral blood flow in the putamen measured with positron emission tomography.

To minimize the influence of exogenous factors, 13 volunteers were anesthetized with sevoflurane 1 MAC while exposed to manual acupuncture stimulation of LI-4 (Group 1, n = 7) or a placebo point in the space between the third and fourth metacarpals (Group II, n = 6). During anesthesia (baseline) and anesthesia + acupuncture, one H2(15)O scan was performed, respectively. Group I demonstrated a significant decrease in regional cerebral blood flow in the right medial frontal gyrus (20%) and in the left putamen (17%).

The effects of indomethacin on intracranial pressure and cerebral hemodynamics during isoflurane or propofol anesthesia in sheep with intracranial hypertension.

The effect of indomethacin in reducing intracranial pressure (ICP) may be dependent on the choice of anesthetic regimen. We studied the effects of indomethacin on ICP and cerebral blood flow (CBF) during isoflurane or propofol anesthesia in a sheep model of intracranial hypertension. A crossover design was applied in which six sheep were anesthetized with isoflurane and propofol in a random order.

Effects of dose-dependent levels of isoflurane on cerebral blood flow in healthy subjects studied using positron emission tomography.

Background: In this study, we tested the hypothesis that escalating drug concentrations of isoflurane are associated with a significant decline in cerebral blood flow (CBF) in regions sub-serving conscious brain activity, including specifically the thalamus.

Methods: Nine human volunteers received three escalating drug concentrations: 0.2, 0.

Subdural intracranial pressure, cerebral perfusion pressure, and degree of cerebral swelling in supra- and infratentorial space-occupying lesions in children.

Unlabelled: To our knowledge comparative studies of intracranial pressure (ICP) and degree of cerebral swelling during craniotomy for supratentorial or infratentorial space occupying lesion in children are not available. In this prospective study subdural ICP, cerebral perfusion pressure (CPP), dural tension, and the degree of cerebral swelling were analysed in supine and prone positioned children subjected to craniotomy for space occupying lesions.

Material And Method: 48 children with space occupying tumours were subjected to either isoflurane/nitrous oxide 50%/fentanyl (n = 22) or propofol/fentanyl/air/oxygen (n = 26).

The effects of 10 degrees reverse Trendelenburg position on subdural intracranial pressure and cerebral perfusion pressure in patients subjected to craniotomy for cerebral aneurysm.

The aim of the current study was to examine the effects of 10 degrees reverse Trendelenburg position (rTp) on subdural intracranial pressure (ICP), cerebral perfusion pressure (CPP), and dural tension. Additionally, the relationship between preoperative Hunt and Hess (H and H) grade and the subdural ICP in patients scheduled for cerebral aneurysm surgery was investigated. Twenty-eight consecutive patients with a cerebral aneurysm were subjected to craniotomy in propofol/fentanyl or propofol/remifentanil anesthesia.

Cerebral metabolic response to low blood flow: possible role of cytochrome oxidase inhibition.

The reactions of cerebral metabolism to imposed changes of cerebral blood flow (CBF) are poorly understood. A common explanation of the mismatched CBF and oxygen consumption (CMR(O(2))) during neuronal excitation holds that blood flow rises more than oxygen consumption to compensate for an absent oxygen reserve in brain mitochondria. The claim conversely implies that oxygen consumption must decline when blood flow declines.

Effect of alfentanil on intracranial pressure during propofol-fentanyl anesthesia for craniotomy. A randomized prospective dose-response study.

Background: The effect of alfentanil on intracranial pressure (ICP) in patients with supratentorial cerebral tumors has only been sparsely examined and with somewhat contradictory results.

Methods: Thirty-one patients were anesthetized with propofol and fentanyl. After removal of the bone flap a bolus-dose of alfentanil 10 (group 1), 20 (group 2), or 30 microg kg(-1) (group 3) was administered followed by an infusion of 10, 20, or 30 microg.

Effects of subanaesthetic and anaesthetic doses of sevoflurane on regional cerebral blood flow in healthy volunteers. A positron emission tomographic study.

Background: We tested the hypothesis that escalating drug concentrations of sevoflurane are associated with a significant decline of cerebral blood flow in regions subserving conscious brain activity, including specifically the thalamus.

Methods: Nine healthy human volunteers received three escalating doses using 0.4%, 0.

Craniotomy for supratentorial brain tumors: risk factors for brain swelling after opening the dura mater.

Object: Cerebral swelling often occurs during craniotomy for cerebral tumors. The primary aim in this study was to determine risk factors (intracranial pressure [ICP], patient characteristics, histopathological features, neuroimaging characteristics, anesthetic regimen, and perioperative physiological data) predictive of brain swelling through the dural opening. As a secondary aim the authors attempted to define subdural ICP thresholds associated with brain swelling.

Do indomethacin and propofol cause cerebral ischemic damage? Diffusion-weighted magnetic resonance imaging in patients undergoing craniotomy for brain tumors.

Background: Diffusion-weighted magnetic resonance imaging was used to determine whether indomethacin and propofol induce cerebral ischemic damage in patients undergoing craniotomy for cerebral tumors. As a secondary aim, the authors investigated whether low jugular bulb oxygen saturation values were associated with brain parenchymal damage as evaluated by diffusion-weighted imaging.

Methods: Nine patients subjected to craniotomy for supratentorial brain tumors in propofol-fentanyl anesthesia were studied.

The effects of indomethacin on intracranial pressure and cerebral haemodynamics in patients undergoing craniotomy: a randomised prospective study.

We compared the effects of indomethacin (bolus of 0.2 mg.kg-1 followed by an infusion of 0.

The ICP-lowering effect of 10 degrees reverse Trendelenburg position during craniotomy is stable during a 10-minute period.

Recently we studied the effect of 10 degrees reverse Trendelenburg position on subdural pressure and cerebral perfusion pressure (CPP) during craniotomy. Within 1 minute we found a significant decrease in subdural pressure while CPP was unchanged. A longer time span, however, is necessary to exclude a temporary effect.

No influence of the endothelin receptor antagonist bosentan on basal and indomethacin-induced reduction of cerebral blood flow in pigs.

Background: The mechanism behind indomethacin-induced cerebral vasoconstriction is incompletely understood. We tested the hypothesis that the mixed endothelin-1 receptor antagonist bosentan would modify or prevent indomethacin-induced reduction of CBF in the anaesthetized pig. Furthermore, we investigated the effect of bosentan on resting CBF and CMRO2.

Intracranial pressure and cerebral hemodynamic in patients with cerebral tumors: a randomized prospective study of patients subjected to craniotomy in propofol-fentanyl, isoflurane-fentanyl, or sevoflurane-fentanyl anesthesia.

Background: A critical point during craniotomy is opening of dura, where a high intracranial pressure (ICP) results in swelling of cerebral tissue. Controlled studies concerning ICP, degree of dural tension, and degree of cerebral swelling are therefore warranted.

Methods: In an open-label study, 117 patients with supratentorial cerebral tumors were randomized to propofol-fentanyl (group 1), isoflurane-fentanyl (group 2), or sevoflurane-fentanyl anesthesia (group 3).

The effects of 10 degrees reverse trendelenburg position on ICP and CPP in prone positioned patients subjected to craniotomy for occipital or cerebellar tumours.

Background: Control of ICP-hypertension is of utmost importance during craniotomy. The effects of reverse Trendelenburg position (RTP) upon ICP and CPP have recently been studied in supine positioned patients.

Method: In this study we investigated changes in intracranial pressure (ICP), mean arterial blood pressure (MABP), CPP and jugular bulb pressure (JBP) before and one minute after 10( degrees ) RTP in 26 prone positioned patients with either occipital (n=12) or cerebellar tumours (n=14).

ICP is lower during propofol anaesthesia compared to isoflurane and sevoflurane.

Objectives: Propofol is a cerebral vasoconstrictor while inhalation anaesthetics like isoflurane and sevoflurane act as cerebral vasodilators in both animal and human studies. This difference of action upon cerebral vessels might implicate a lower ICP during propofol anaesthesia. Cerebral metabolism is decreased by all three anaesthetics.