Blood-brain Barrier Permeability May Influence Vasopressor Effects in Anesthetized Patients With Brain Tumor: An Analysis of Magnetic Resonance Imaging Data.

OBJECTIVE: This is a secondary analysis of data from a previous study of anesthetized brain tumor patients receiving ephedrine or phenylephrine infusions. 18 patients with magnetic imaging verified tumor contrast enhancement were included. We hypothesized that vasopressors induce microcirculatory flow changes, characterized by increased capillary transit time heterogeneity (CTH) and decreased mean transit time (MTT), in brain regions exhibiting BBB leakage. METHODS: This is a secondary analysis of data from a previous study of anesthetized brain tumor patients receiving ephedrine or phenylephrine infusions. 18 patients with magnetic imaging verified tumor contrast enhancement were included. Postvasopressor to prevasopressor ratios of CTH, MTT, relative transit time heterogeneity (RTH), cerebral blood flow (CBF), cerebral blood volume, and oxygen extraction fraction (OEF) were calculated in tumor, peritumoral, hippocampal, and contralateral grey matter regions. Comparisons were made between brain regions and vasopressors. RESULTS: During phenylephrine infusion, ratios of CTH, RTH, and CBF were greater, and ratios of MTT and OEF were lower, in the tumor region with contrast leakage compared with corresponding contralateral grey matter ratios. During ephedrine infusion, ratios of CTH, MTT, RTH, CBF, and cerebral blood volume were higher in the tumor region with leakage compared with contralateral grey matter ratios. In addition, the ratio of CBF was higher in all regions, the ratio of RTH was lower in the leaking tumor region, and the ratio of OEF was lower in peritumoral, hippocampal, and grey matter regions with ephedrine compared with phenylephrine. CONCLUSIONS: Vasopressors can induce distinct microcirculatory flow alterations in regions with compromised brain tumor barrier or BBB. Ephedrine, a combined α and ß-adrenergic agonist, appears to result in fewer flow alterations and less impact on tissue oxygenation compared with phenylephrine, a pure α-adrenergic agonist.

Correlation Between Cerebral Tissue Oxygen Saturation and Oxygen Extraction Fraction During Anesthesia: Monitoring Cerebral Metabolic Demand-supply Balance During Vasopressor Administration.

BACKGROUND: The speculation that cerebral tissue oxygen saturation (SctO 2 ) measured using tissue near-infrared spectroscopy reflects the balance between cerebral metabolic rate of oxygen and cerebral oxygen delivery has not been validated. Our objective was to correlate SctO 2 with cerebral oxygen extraction fraction (OEF) measured using positron emission tomography; OEF is the ratio between cerebral metabolic rate of oxygen and cerebral oxygen delivery and reflects the balance between these 2 variables. MATERIALS AND METHODS: This cohort study was based on data collected in a previously published trial assessing phenylephrine versus ephedrine treatment in anesthetized patients undergoing brain tumor surgery. The variables of interest were measured twice over the healthy hemisphere before surgery: the first measurement performed after anesthesia induction and the second measurement performed after induction of a ∼20% increase in blood pressure using either phenylephrine or ephedrine. RESULTS: Data from 24 patients were analyzed. The overall vasopressor-induced relative changes in SctO 2 (ΔSctO 2 ) and OEF (ΔOEF) were 3.16% [interquartile range, -0.73% to 6.04%] and -12.5% [interquartile range, -24.0% to -6.19%], respectively. ΔSctO 2 negatively correlated with ΔOEF after phenylephrine treatment (Spearman rank correlation coefficient [ rs ]=-0.76; P =0.007), ephedrine treatment ( rs =-0.76; P =0.006), and any treatment ( rs =-0.79; P <0.001). ΔSctO 2 significantly associated with ΔOEF based on multivariable analysis with ΔOEF, relative changes in mean arterial pressure, arterial blood oxygen tension, and the bispectral index as covariates ( P =0.036). CONCLUSIONS: The negative correlation between changes in SctO 2 and OEF suggests that SctO 2 may reflect the cerebral metabolic demand-supply balance during vasopressor treatment. The generalizability of our findings in other clinical scenarios remains to be determined.

Cerebral Macro- and Microcirculation during Ephedrine versus Phenylephrine Treatment in Anesthetized Brain Tumor Patients: A Randomized Clinical Trial Using Magnetic Resonance Imaging.

BACKGROUND: This study compared ephedrine versus phenylephrine treatment on cerebral macro- and microcirculation, measured by cerebral blood flow, and capillary transit time heterogeneity, in anesthetized brain tumor patients. The hypothesis was that capillary transit time heterogeneity in selected brain regions is greater during phenylephrine than during ephedrine, thus reducing cerebral oxygen tension. METHODS: In this single-center, double-blinded, randomized clinical trial, 24 anesthetized brain tumor patients were randomly assigned to ephedrine or phenylephrine. Magnetic resonance imaging of peritumoral and contralateral hemispheres was performed before and during vasopressor infusion. The primary endpoint was between-group difference in capillary transit time heterogeneity. Secondary endpoints included changes in cerebral blood flow, estimated oxygen extraction fraction, and brain tissue oxygen tension. RESULTS: Data from 20 patients showed that mean (± SD) capillary transit time heterogeneity in the contralateral hemisphere increased during phenylephrine from 3.0 ± 0.5 to 3.2 ± 0.7 s and decreased during ephedrine from 3.1 ± 0.8 to 2.7 ± 0.7 s (difference phenylephrine versus difference ephedrine [95% CI], -0.6 [-0.9 to -0.2] s; P = 0.004). In the peritumoral region, the mean capillary transit time heterogeneity increased during phenylephrine from 4.1 ± 0.7 to 4.3 ± 0.8 s and decreased during ephedrine from 3.5 ± 0.9 to 3.3 ± 0.9 s (difference phenylephrine versus difference ephedrine [95%CI], -0.4[-0.9 to 0.1] s; P = 0.130). Cerebral blood flow (contralateral hemisphere ratio difference [95% CI], 0.3 [0.06 to 0.54]; P = 0.018; and peritumoral ratio difference [95% CI], 0.3 [0.06 to 0.54; P = 0.018) and estimated brain tissue oxygen tension (contralateral hemisphere ratio difference [95% CI], 0.34 [0.09 to 0.59]; P = 0.001; and peritumoral ratio difference [95% CI], 0.33 [0.09 to 0.57]; P = 0.010) were greater during ephedrine than phenylephrine in both regions. CONCLUSIONS: Phenylephrine caused microcirculation in contralateral tissue, measured by the change in capillary transit time heterogeneity, to deteriorate compared with ephedrine, despite reaching similar mean arterial pressure endpoints. Ephedrine improved cerebral blood flow and tissue oxygenation in both brain regions and may be superior to phenylephrine in improving cerebral macro- and microscopic hemodynamics and oxygenation.

Ephedrine versus Phenylephrine Effect on Cerebral Blood Flow and Oxygen Consumption in Anesthetized Brain Tumor Patients: A Randomized Clinical Trial.

BACKGROUND: Studies in anesthetized patients suggest that phenylephrine reduces regional cerebral oxygen saturation compared with ephedrine. The present study aimed to quantify the effects of phenylephrine and ephedrine on cerebral blood flow and cerebral metabolic rate of oxygen in brain tumor patients. The authors hypothesized that phenylephrine reduces cerebral metabolic rate of oxygen in selected brain regions compared with ephedrine. METHODS: In this double-blinded, randomized clinical trial, 24 anesthetized patients with brain tumors were randomly assigned to ephedrine or phenylephrine treatment. Positron emission tomography measurements of cerebral blood flow and cerebral metabolic rate of oxygen in peritumoral and normal contralateral regions were performed before and during vasopressor infusion. The primary endpoint was between-group difference in cerebral metabolic rate of oxygen. Secondary endpoints included changes in cerebral blood flow, oxygen extraction fraction, and regional cerebral oxygen saturation. RESULTS: Peritumoral mean ± SD cerebral metabolic rate of oxygen values before and after vasopressor (ephedrine, 67.0 ± 11.3 and 67.8 ± 25.7 µmol · 100 g · min; phenylephrine, 68.2 ± 15.2 and 67.6 ± 18.0 µmol · 100 g · min) showed no intergroup difference (difference [95% CI], 1.5 [-13.3 to 16.3] µmol · 100 g · min [P = 0.839]). Corresponding contralateral hemisphere cerebral metabolic rate of oxygen values (ephedrine, 90.8 ± 15.9 and 94.6 ± 16.9 µmol · 100 g · min; phenylephrine, 100.8 ± 20.7 and 96.4 ± 17.7 µmol · 100 g · min) showed no intergroup difference (difference [95% CI], 8.2 [-2.0 to 18.5] µmol · 100 g · min [P = 0.118]). Ephedrine significantly increased cerebral blood flow (difference [95% CI], 3.9 [0.7 to 7.0] ml · 100 g · min [P = 0.019]) and regional cerebral oxygen saturation (difference [95% CI], 4 [1 to 8]% [P = 0.024]) in the contralateral hemisphere compared to phenylephrine. The change in oxygen extraction fraction in both regions (peritumoral difference [95% CI], -0.6 [-14.7 to 13.6]% [P = 0.934]; contralateral hemisphere difference [95% CI], -0.1 [- 12.1 to 12.0]% [P = 0.989]) were comparable between groups. CONCLUSIONS: The cerebral metabolic rate of oxygen changes in peritumoral and normal contralateral regions were similar between ephedrine- and phenylephrine-treated patients. In the normal contralateral region, ephedrine was associated with an increase in cerebral blood flow and regional cerebral oxygen saturation compared with phenylephrine.

Effects of Vasopressors on Cerebral Circulation and Oxygenation: A Narrative Review of Pharmacodynamics in Health and Traumatic Brain Injury.

The clinical use of vasoactive drugs aims to improve hemodynamic variables and thereby maintain or restore adequate perfusion and oxygenation in accordance with metabolic demands. A main focus in the management of patients with brain pathology during surgery and neurointensive care is restoring and/or maintaining adequate cerebral perfusion pressure in order to ensure cerebral blood flow in accordance with metabolic demands. One commonly used clinical strategy is the administration of vasoactive drugs aiming to increase mean arterial blood pressure and thereby cerebral perfusion pressure. Here, we first describe the anatomic and physiological basis for the cerebrovascular effects of vasopressor agents. Next, we review the pharmacodynamics of commonly used vasopressors under normal circumstances and in the presence of head injury. We further discuss the role of blood-brain barrier disruption and microvascular dysfunction with regard to the effects of the reviewed vasopressor agents.

[Reposition of nose fractures under local or general anaesthesia. A retrospective patient satisfaction survey]. / Reposition af naesefrakturer i lokal anaestesi versus generel anaestesi. En retrospektiv patienttilfredshedsundersøgelse.

INTRODUCTION: Nose fractures are the most common among facial fractures. A well-approved treatment of isolated nose fractures is closed reposition under local or general anaesthesia. MATERIALS AND METHODS: This study included 150 patients who were treated with closed reposition for simple and isolated nose fracture at the Otorhinolaryngology Department of Odense University Hospital during the period 1 January 2003 until 31 December 2004. The case records were retrospectively examined and the patients were sent a questionnaire and were offered outpatient follow-up. RESULTS: The most frequent cause of damage was violence. The average interval from trauma to treatment was 4.1 days. 60% of the patients filed cosmetic results equal to or better than before fracturing the nose regardless of the anaesthetic procedure, while 69% of the patients experienced the function of the nose as equal to or better than before. CONCLUSION: The majority of nose fractures are treated under local anaesthesia. A follow-up at least 1 year later found no difference between patient satisfaction of cosmetic and functional results of the nose, regardless of whether they had local or general anaesthesia. In general, the patients were satisfied with the anaesthesia, whether it was local or general.