Brenton Alexander

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BACKGROUND How phenylephrine and ephedrine treatments affect global and regional haemodynamics is of major clinical relevance. Cerebral tissue oxygen saturation (Sct(O2) )-guided management may improve postoperative outcome. The physiological variables responsible for Sct(O2) changes induced by phenylephrine and ephedrine bolus treatment in anaesthetized(More)
BACKGROUND Multiple studies have shown that cerebral tissue oxygen saturation (Sct(O(2))) is decreased after phenylephrine treatment. We hypothesized that the negative impact of phenylephrine administration on Sct(O(2)) is affected by arterial blood carbon dioxide partial pressure (Pa(CO(2))) because CO(2) is a powerful modulator of cerebrovascular tone. (More)
INTRODUCTION Dynamic predictors of fluid responsiveness have made automated management of fluid resuscitation more practical. We present initial simulation data for a novel closed-loop fluid-management algorithm (LIR, Learning Intravenous Resuscitator). METHODS The performance of the closed-loop algorithm was tested in three phases by using a patient(More)
BACKGROUND While the decrease in blood carbon dioxide (CO2 ) secondary to hyperventilation is generally accepted to play a major role in the decrease of cerebral tissue oxygen saturation (SctO2 ), it remains unclear if the associated systemic hemodynamic changes are also accountable. METHODS Twenty-six patients (American Society of Anesthesiologists I-II)(More)
Hemodynamic monitoring and management has greatly improved during the past decade. Technologies have evolved from very invasive to non-invasive, and the philosophy has shifted from a static approach to a functional approach. However, despite these major changes, the critical care community still has potential to improve its ability to adopt the most modern(More)
Pulse pressure variation (PPV) can be monitored several ways, but according to recent survey data it is most often visually estimated ("eyeballed") by practitioners. It is not known how accurate visual estimation of PPV is, or whether eyeballing of PPV in goal-directed fluid therapy studies may limit the ability to blind the control group to PPV value. The(More)
Pulse pressure variation can predict fluid responsiveness in strict applicability conditions. The purpose of this study was to describe the clinical applicability of pulse pressure variation during episodes of patient hemodynamic instability in the intensive care unit. We conducted a five-day, seven-center prospective study that included patients presenting(More)
Editor's key points † Effects of different vasopressor agents on cerebral oxygenation have been unclear. † Ephedrine and phenylephrine, used for intraoperative hypotension, were investigated in a cross-over design study. † Phenylephrine, but not ephedrine, decreased cardiac output (CO) and brain oxygenation. † This study highlights the importance of CO in(More)
This paper presents the spectroscopic performance of two newly developed pixelated HgI2 detectors. These detectors are 1 × 1 × 0.814 cm3 and 1 × 1 × 1.016 cm3 in size. Each detector has four closely packed 1 × mm2 anode pixels at the center of one of the 1 × 1 cm2 surfaces. These anode pixels are surrounded by a large anode. All results presented here are(More)
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