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Search Results: 1 - 10 of 301951 matches for " Kenneth J. Warring-Davies "
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Validating HeartSmart® against the Cardiopulmonary Bypass Machine  [PDF]
Kenneth J. Warring-Davies, Martin J. Bland
Surgical Science (SS) , 2012, DOI: 10.4236/ss.2012.31004
Abstract: Purpose: To assess the utility of HeartSmart?, a new method that uses empirical physiological formulae to estimate hemodynamic variables, in estimating cardiac index during open heart surgery when compared with the cardiopulmonary bypass machine. Methods: This was a prospective, blinded study of patients undergoing elective cardiac bypass surgery. We monitored and compared the flow rates provided by the cardiopulmonary bypass machine (roller pump) with estimates derived from the empirical physiological formulae embedded in the HeartSmart? monitor in 32 patients. Cardiac index values were compared at the start of cardiopulmonary bypass, during re-warming, and at the end of cardiopulmonary bypass. Results: A total of 256 paired sets of measurements were suitable for comparison. The mean of the differences or bias (95% limits of agreement) was 0.09 l/min/m2 and the limits of agreement –0.86 to 1.05 l/min/m2. The mean difference of the sets of 256 measurements was 585.5 l/min/m for the pump and 575.0 l/min/m2 for the empirical physiological formulae—a difference of 5% l/min/m2. The range of flow rates for the pump was 1.2 to 2.85 l/min/m2; for the empirical physiological formulae, the range was 1.2 to 3.0 l/min/m2. Conclusion: The cardiac index estimates derived from the empirical physiological formulae in the HeartSmart? software are in good agreement with pump cardiac output rates. These results suggest that HeartSmart? measurements are sufficiently accurate for assessing hemodynamic variables in many groups of patients.
HeartSmartTM: A New Method of Assessing Hydration in Neurosurgical Patients  [PDF]
Kenneth James Warring-Davies, John Martin Bland
Surgical Science (SS) , 2012, DOI: 10.4236/ss.2012.311108
Abstract: Background: Maintenance of normal fluid homeostasis is challenging in neurosurgical patients. Consequently, we studied hydration assessment in neurosurgical intensive care patients. Methods: Pulmonary artery catheter thermodilution (PACTD) is the conventional method for measuring cardiac index (CI) and mean pulmonary artery occlusion (MPAOP) or wedge pressure (MPWP). We compared values from this technique with those derived from continuous cardiac dynamic monitoring (CCDM)-HeartSmart?, a new, less invasive, software-based technique. Over 4 years, we undertook an audit of 101 paired sets of data from 21 patients with sub-arachnoid hemorrhage who had pulmonary artery flotation catheters inserted as part of their treatment. Measured values of CI and MPWP were obtained retrospectively from patients’ charts and compared with values calculated using CCDM-HeartSmart? software. Results: Using the Bland-Altman method for comparing two measurement techniques, there was good agreement between measured and calculated MPWP (mean of differences –1.81, SD 3.97, SE 0.39, 95% CI –2.59 to 2.04 l/min/m2; two-sided p < 0.0001). The measured and calculated values of CI were also in good agreement (mean of differences 0.36, SD 1.30, SE 0.13, 95% CI 0.109 - 0.619; two-sided p = 0.0055, 95% limits of agreement –2.1 to 2.91 l/min/m2). This indicates that, when estimating CI and MPWP in critically ill neurosurgical patients, CCDM-HeartSmart? provides values close to those generated using PACTD. Conclusions: The CCDM-HeartSmart? could prove invaluable for optimizing response to fluid replacement and for guiding cardiovascular support in neurosurgical patients. This new, simple technology may help to facilitate routine adoption of perioperative optimization of blood flow using early goal-directed therapy.
HeartSmart for routine optimization of blood flow and facilitation of early goal-directed therapy
Kenneth Warring-Davies, Martin Bland
Open Access Journal of Clinical Trials , 2010, DOI: http://dx.doi.org/10.2147/OAJCT.S9843
Abstract: rtSmart for routine optimization of blood flow and facilitation of early goal-directed therapy Original Research (2811) Total Article Views Authors: Kenneth Warring-Davies, Martin Bland Published Date August 2010 Volume 2010:2 Pages 115 - 123 DOI: http://dx.doi.org/10.2147/OAJCT.S9843 Kenneth Warring-Davies1, Martin Bland2 1The Intensive Care Unit, Bradford Royal Infirmary, Bradford, West Yorkshire, UK; 2Department of Health Sciences, University of York, York, North Yorkshire, UK Abstract: The empirical physiological formulae of the new continuous cardiac dynamic -monitoring HeartSmart technology, which involves the use of a new inverse square rule of the heart, were investigated with pulmonary artery catheter (PAC) thermodilution in the -estimation of CI in diverse patients. Clinical trial data collected from 268 adult surgery or intensive care patients requiring PAC placement were obtained from 7 NHS Trust hospitals, providing 2720 paired sets of CI estimations for comparison between HeartSmart and PAC thermodilution. For 95% of pairs of measurements, HeartSmart values were between 57% and 164% of PAC measurements; additionally, the larger limit of agreement between HeartSmart and PAC thermodilution (1.26 L min-1 m-2) suggests that HeartSmart agrees with PAC thermodilution as closely as PAC thermodilution agrees with itself. HeartSmart can also estimate CI in the extreme circumstances of shock/sepsis, as indicated by PAC thermodilution CI values that were hypo- or hyperdynamic based on systemic inflammatory response syndrome criteria. In CI measurements for hypo- or hyperdynamic values that were matched between HeartSmart and PAC thermodilution, the difference in total volumes and average CI measurements between the two methods was less than 5%. For unmatched hypo- or hyperdynamic values, the difference between total volumes and average CI measurements was less than 33% – an acceptable percentage of difference or error even for normal values of CI. HeartSmart tracked PAC thermodilution CI hypodynamic values 98.2% of the time and hyperdynamic values 97.6% of the time. These findings show that CI estimations provided by the HeartSmart empirical physiological formulae are comparable to those obtained using PAC thermodilution. HeartSmart removes many of the technical barriers that prevent the routine adoption and practice of early goal-directed therapy, and represents a simple, reliable method of estimating CI and other hemodynamic variables at the bedside or in departments other than the Intensive Care Unit.
HeartSmart® for routine optimization of blood flow and facilitation of early goal-directed therapy
Kenneth Warring-Davies,Martin Bland
Open Access Journal of Clinical Trials , 2010,
Abstract: Kenneth Warring-Davies1, Martin Bland21The Intensive Care Unit, Bradford Royal Infirmary, Bradford, West Yorkshire, UK; 2Department of Health Sciences, University of York, York, North Yorkshire, UKAbstract: The empirical physiological formulae of the new continuous cardiac dynamic -monitoring HeartSmart technology, which involves the use of a new inverse square rule of the heart, were investigated with pulmonary artery catheter (PAC) thermodilution in the -estimation of CI in diverse patients. Clinical trial data collected from 268 adult surgery or intensive care patients requiring PAC placement were obtained from 7 NHS Trust hospitals, providing 2720 paired sets of CI estimations for comparison between HeartSmart and PAC thermodilution. For 95% of pairs of measurements, HeartSmart values were between 57% and 164% of PAC measurements; additionally, the larger limit of agreement between HeartSmart and PAC thermodilution (1.26 L min-1 m-2) suggests that HeartSmart agrees with PAC thermodilution as closely as PAC thermodilution agrees with itself. HeartSmart can also estimate CI in the extreme circumstances of shock/sepsis, as indicated by PAC thermodilution CI values that were hypo- or hyperdynamic based on systemic inflammatory response syndrome criteria. In CI measurements for hypo- or hyperdynamic values that were matched between HeartSmart and PAC thermodilution, the difference in total volumes and average CI measurements between the two methods was less than 5%. For unmatched hypo- or hyperdynamic values, the difference between total volumes and average CI measurements was less than 33% – an acceptable percentage of difference or error even for normal values of CI. HeartSmart tracked PAC thermodilution CI hypodynamic values 98.2% of the time and hyperdynamic values 97.6% of the time. These findings show that CI estimations provided by the HeartSmart empirical physiological formulae are comparable to those obtained using PAC thermodilution. HeartSmart removes many of the technical barriers that prevent the routine adoption and practice of early goal-directed therapy, and represents a simple, reliable method of estimating CI and other hemodynamic variables at the bedside or in departments other than the Intensive Care Unit.Keywords: cardiac index, early goal-directed therapy, HeartSmart , cardiodynamics, blood flow
Successful Treatment of Recurrent Primary Sclerosing Cholangitis after Orthotopic Liver Transplantation with Oral Vancomycin
Yinka K. Davies,Cynthia J. Tsay,Dario V. Caccamo,Kathleen M. Cox,Ricardo O. Castillo,Kenneth L. Cox
Case Reports in Transplantation , 2013, DOI: 10.1155/2013/314292
Abstract: Primary sclerosing cholangitis (PSC) is a progressive, cholestatic disease of the liver that is marked by inflammation of the bile ducts and damage to the hepatic biliary tree. Approximately 60–70% of patients also have inflammatory bowel disease and progression of PSC can lead to ulcerative colitis and cirrhosis of the liver. Due to limited understanding of the etiology and mechanism of PSC, the only existing treatment option is orthotopic liver transplantation (OLT); however, recurrence of PSC, after OLT is estimated to be between 5% and 35%. We discuss the successful treatment of a pediatric patient, with recurrent PSC, after OLT with oral Vancomycin. 1. Introduction Primary sclerosing cholangitis (PSC) is a progressive inflammatory disease, of unknown etiology and with significant morbidity and mortality, which damages the intra- and/or extrahepatic biliary tree leading to portal hypertension and cirrhosis of the liver. The clinical course is variable including hepatobiliary carcinoma, especially cholangiocarcinoma in 6–20% of patients [1–6]. Additionally, it is estimated that 60–70% of people with PSC have inflammatory bowel disease [7, 8]. Orthotopic liver transplantation (OLT) is the only treatment option for patients with end-stage liver disease due to the progressive damage caused from PSC [9, 10]. The recurrence of PSC in the new graft is estimated to be between 5–35% [11–13]. We report the successful treatment of a patient after OLT, who had shown recurrence of disease, with oral Vancomycin. 2. Case Report A 12-year-old girl presented with a three-week history of jaundice and lethargy, with periumbilical pain every other day. There had been no recent travel or sick contacts. Screening tests revealed platelet level was low (89?K/uL; normal range 150 to 400). Antinuclear Antibody (ANCA) was positive with a homogeneous pattern, and Antinuclear Antibody Titer was elevated (640; normal range <40). Serum copper was normal at 1065?ug/L and ceruloplasmin was normal at 24?mg/dL. γ-Glutamyl transpeptidase (GGT) level was elevated (139?U/L; reference range from 5 to 36). C-Reactive Protein (CRP) was elevated at 2.80?mg/dL; reference range was from 0.0 to 0.5. PTT was elevated at 48.6?sec; normal range was from 23.3 to 33.8. Prothrombin Time was elevated at 21.0?sec; normal range was from 11.8 to 14.2. INR was increased to 1.9?sec; normal range was from 0.9 to 1.1. Erythrocyte sedimentation rate (ESR) was elevated at 107?mm/hr; bilirubin was elevated at 3.5?mg/dL, and ammonia was elevated at 55?umol/L. Patient underwent an open liver biopsy, which
Electric field and photo-excited control of the carrier concentration in GdN
Harry Warring,B. J. Ruck,H. J. Trodahl,F. Natali
Physics , 2013, DOI: 10.1063/1.4800455
Abstract: We present both electric-field and photo-excited control of the carrier concentration in GdN. There is no evidence in the results of a carrier-mediated contribution to the Gd-Gd exchange interaction that has been suggested to explain a measured Curie temperature that is much higher than obtained within theoretical treatments. Persistent carrier concentrations seen in both the field-effect and photo-induced conductivities point to a distribution of long-lived trap states below the conduction band, very likely centred at nitrogen vacancies
Arbitrary Waveform Generator for Quantum Information Processing with Trapped Ions
R. Bowler,U. Warring,J. W. Britton,B. C. Sawyer,J. Amini
Physics , 2013, DOI: 10.1063/1.4795552
Abstract: Atomic ions confined in multi-electrode traps have been proposed as a basis for scalable quantum information processing. This scheme involves transporting ions between spatially distinct locations by use of time-varying electric potentials combined with laser or microwave pulses for quantum logic in specific locations. We report the development of a fast multi-channel arbitrary waveform generator for applying the time-varying electric potentials used for transport and for shaping quantum logic pulses. The generator is based on a field-programmable gate array controlled ensemble of 16-bit digital-to-analog converters with an update frequency of 50 MHz and an output range of $\pm$10 V. The update rate of the waveform generator is much faster than relevant motional frequencies of the confined ions in our experiments, allowing diabatic control of the ion motion. Numerous pre-loaded sets of time-varying voltages can be selected with 40 ns latency conditioned on real-time signals. Here we describe the device and demonstrate some of its uses in ion-based quantum information experiments, including speed-up of ion transport and the shaping of laser and microwave pulses.
Individual-Ion Addressing with Microwave Field Gradients
U. Warring,C. Ospelkaus,Y. Colombe,R. J?rdens,D. Leibfried,D. J. Wineland
Physics , 2012, DOI: 10.1103/PhysRevLett.110.173002
Abstract: Individual-qubit addressing is a prerequisite for many instances of quantum information processing. We demonstrate this capability on trapped-ion qubits with microwave near-fields delivered by electrode structures integrated into a microfabricated surface-electrode trap. We describe four approaches that may be used in quantum information experiments with hyperfine levels as qubits. We implement individual control on two 25Mg+ ions separated by 4.3 micrometer and find spin-flip crosstalk errors on the order of 10^(-3).
Earth's surface heat flux
J. H. Davies,D. R. Davies
Solid Earth (SE) & Discussions (SED) , 2010, DOI: 10.5194/se-1-5-2010
Abstract: We present a revised estimate of Earth's surface heat flux that is based upon a heat flow data-set with 38 347 measurements, which is 55% more than used in previous estimates. Our methodology, like others, accounts for hydrothermal circulation in young oceanic crust by utilising a half-space cooling approximation. For the rest of Earth's surface, we estimate the average heat flow for different geologic domains as defined by global digital geology maps; and then produce the global estimate by multiplying it by the total global area of that geologic domain. The averaging is done on a polygon set which results from an intersection of a 1 degree equal area grid with the original geology polygons; this minimises the adverse influence of clustering. These operations and estimates are derived accurately using methodologies from Geographical Information Science. We consider the virtually un-sampled Antarctica separately and also make a small correction for hot-spots in young oceanic lithosphere. A range of analyses is presented. These, combined with statistical estimates of the error, provide a measure of robustness. Our final preferred estimate is 47±2 TW, which is greater than previous estimates.
Earth's surface heat flux
J. H. Davies,D. R. Davies
Solid Earth Discussions , 2009, DOI: 10.5194/sed-1-1-2009
Abstract: We present a revised estimate of Earth's surface heat flux that is based upon a heat flow data-set with 38 347 measurements, which is 55% more than used in previous estimates. Our methodology, like others, accounts for hydrothermal circulation in young oceanic crust by utilising a half-space cooling approximation. For the rest of Earth's surface, we estimate the average heat flow for different geologic domains as defined by global digital geology maps; and then produce the global estimate by multiplying it by the total global area of that geologic domain. The averaging is done on a polygon set which results from an intersection of a 1 degree equal area grid with the original geology polygons; this minimises the adverse influence of clustering. These operations and estimates are derived accurately using methodologies from Geographical Information Science. We consider the virtually un-sampled Antarctica separately and also make a small correction for hot-spots in young oceanic lithosphere. A range of analyses is presented. These, combined with statistical estimates of the error, provide a measure of robustness. Our final preferred estimate is 47±2 TW, which is greater than previous estimates.
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