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Taunton, United Kingdom

MacIver D.H.,Taunton and Somerset Hospital
European Journal of Echocardiography | Year: 2011

Aims Left ventricular ejection fraction (EF) is a suboptimal measure of ventricular function. Recent mathematical modelling of left ventricular contraction has shown that the EF is determined by both myocardial shortening (strain) and by end-diastolic wall thickness. Increasing end-diastolic wall thickness resulted in augmented radial wall thickening. This may result in a significant 'overestimation' of ventricular systolic function as assessed by the EF. This study proposes a new measure of ventricular systolic function, the corrected EF (EFc) to allow for the presence of concentric left ventricular hypertrophy (LVH). Methods and results The study uses a new two-layer, three-dimensional mathematical model of ventricular contraction. Changes in end-diastolic wall thickness in addition to long-axis and mid-wall circumferential strain were modelled. Iso-strain lines were obtained where myocardial shortening (strain) is constant; EF increases with increasing end-diastolic wall thickness. The corrected EF is determined by following the iso-strain lines to the equivalent EF in the absence of hypertrophy (e.g. 9 mm thickness). For example, an individual with a mean end-diastolic wall thickness of 20 mm and measured EF of 60 has a corrected EF (EFc) of 37. Conclusion The study shows that the EF is determined by absolute wall thickening and provides a nomogram for comparing EF when LVH is present. The EFc is a potential new measure of left ventricular systolic function. Its possible role will need validating in mortality trials. © 2010 The Author. Source


Siassakos D.,Southmead Hospital | Fox R.,Taunton and Somerset Hospital | Crofts J.F.,Southmead Hospital | Hunt L.P.,University of Bristol | And 2 more authors.
Resuscitation | Year: 2011

Objectives: To determine whether team performance in a simulated emergency is related to generic teamwork skills and behaviours. Methods: Design - Cross-sectional analysis of data from the Simulation and Fire-drill Evaluation (SaFE) randomised controlled trial. Setting - Six secondary and tertiary Maternity Units in Southwest England. Participants - 140 healthcare professionals, in 24 teams. Assessment - Blinded analysis of recorded simulations. Main outcome measures - Correlation of team performance (efficiency conducting key clinical actions, including the administration of an essential drug, magnesium), and generic teamwork scores (using a validated tool that assesses skills and behaviours, by Weller et al.). Results: There was significant positive correlation between clinical efficiency and teamwork scores across all three dimensions; skills (Kendall's taub=0.54, p<0.001), behaviours (taub=0.41, p=0.001), and overall score (taub=0.51, p<0.001). Better teams administered the essential drug 2 1/2;min more quickly (Mann-Whitney U, p<0.001). Conclusions: The clinical conduct of a simulated emergency was strongly linked to generic measures of teamwork. Further studies are needed to elucidate which aspects of team working are critical for team performance, to better inform training programs for multi-professional team working. © 2010 Elsevier Ireland Ltd. Source


Fox R.,Taunton and Somerset Hospital | Walker J.J.,University of Leeds | Draycott T.J.,Southmead Hospital
BJOG: An International Journal of Obstetrics and Gynaecology | Year: 2011

From the earliest days of medical practice, when surgeons used cadavers to explore the possibilities of surgical intervention, simulation has been employed to advance the practice of health care. In the last 10 years, technological advances have allowed for a wider availability and greater realism of simulation, and this has encouraged a great expansion in its use. Simulation aims to create a virtuous cycle of professional development to improve patient outcomes. Although it seems eminently logical to believe that simulation will result in better outcomes, there is a need to test these new training interventions rigorously to be sure of their worth and to understand any limitations. The purpose of this BJOG supplement is to examine in depth several paradigms of medical simulation within maternity care and gynaecology, in different settings, looking at what can be achieved and how. In this opening review, we look at the potential use of medical simulation in broad terms and describe the types of evidence that can be employed to support its use. © 2011 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2011 RCOG. Source


The mechanisms of heart failure are ill understood with multiple, heterogeneous hypotheses proposed to describe the condition. This study examines the individual effects of left ventricular hypertrophy, long-axis shortening and the effect of left ventricular remodeling on ejection fraction, end-diastolic volume and stroke volume using a mathematical model of left ventricular contraction. Reducing long-axis shortening caused a decline in stroke volume independently of hypertrophy. Increasing concentric left ventricular hypertrophy resulted in an increase in ejection fraction secondary to augmented wall thickening. A decline in stroke volume occurred despite a preserved ejection fraction when concentric hypertrophy was present. Normalization of stroke volume by remodeling resulted in a marked increase in end-diastolic volume in the absence of hypertrophy and an end-diastolic volume similar to normal in the presence of concentric hypertrophy. The model predicts that the dominant compensatory mechanism in chronic heart failure is remodeling with normalization of stroke volume. Observational data cited supports this conclusion. Source


Siassakos D.,Womens Health | Draycott T.J.,Womens Health | Crofts J.F.,Womens Health | Hunt L.P.,Institute of Child Life and Health | And 2 more authors.
BJOG: An International Journal of Obstetrics and Gynaecology | Year: 2010

Objective To assess whether team performance in simulated eclampsia is related to the knowledge, skills and attitudes of individual team members. Design Cross-sectional analysis of data from the Simulation and Fire Drill Evaluation randomised controlled trial. Setting Six secondary and tertiary maternity units in south-west England. Participants One hundred and fourteen maternity professionals in 19 teams of six members; one senior and one junior obstetrician; two senior and two junior midwives. Methods We validated a team performance ranking scheme with respect to magnesium administration (Magnesium Administration Rank, MAR) by expert consensus (face validity) and correlation with clinical measures (construct validity). We tested for correlation between MAR and measures of knowledge, skills and attitudes. Main outcome measures Correlation between team performance (MAR) and scores in validated multiple-choice questionnaires (MCQs) (knowledge), a measure of individual manual skill to manage an obstetric emergency (skill) and scores in a widely used teamworksafety attitude questionnaire (attitude). Results There was no relationship between team performance and cumulative individual MCQs, skill or teamworksafety attitude scores. Conclusions The knowledge, manual skills and attitudes of the individuals comprising each team, measured by established methods, did not correlate in this study with the team's clinical efficiency in the management of simulated eclampsia. The inference is that unidentified characteristic(s) play a crucial part in the efficiency of teams managing emergencies. Any emphasis of training programmes to promote individual knowledge, skills and attitudes alone may have to be re-examined. This highlights a need to understand what makes a team efficient in dealing with clinical emergencies. © RCOG 2010 BJOG An International Journal of Obstetrics and Gynaecology. Source

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