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Chermside, Australia

Dare A.J.,University of Auckland | Bartlett A.S.,University of Auckland | Fraser J.F.,Critical Care Research Group
Current Neurology and Neuroscience Reports | Year: 2012

Organ transplantation represents one of the great success stories of 20th century medicine. However, its continued success is greatly limited by the shortage of donor organs. This has led to an increased focus within the critical care community on optimal identification and management of the potential organ donor. The multi-organ donor can represent one of the most complex intensive care patients, with numerous competing physiological priorities. However, appropriate management of the donor not only increases the number of organs that can be successfully donated but has long-term implications for the outcomes of multiple recipients. This review outlines current understandings of the physiological derangements seen in the organ donor and evaluates the available evidence for management strategies designed to optimize donation potential and organ recovery. Finally, emerging management strategies for the potential donor are discussed within the current ethical and legal frameworks permitting donation after both brain and circulatory death. © Springer Science+Business Media, LLC 2012.

Gaddum N.R.,Queensland University of Technology | Timms D.L.,Critical Care Research Group | Pearcy M.J.,Queensland University of Technology
Artificial Organs | Year: 2010

Recent studies into rotary biventricular support have indicated that inadequate left/right flow balancing may lead to vascular congestion and/or ventricular suckdown. The implementation of a passive controller that automatically adjusts left/right flow during total and partial cardiac support would improve physiological interaction. This has encouraged the development of a biventricular assist device (BiVAD) prototype that achieves passive control of the two rotary pumps' hydraulic output by way of a nonrotating double pressure plate configuration, the hub, suspended between the ventricular assist device (VAD) impellers. Fluctuations in either the VAD's inlet or outlet pressure will cause the hub to translate, and in doing so, affect each pump's hydraulic outputs. In order to achieve partial support, the floating assembly needed to respond to pathologic blood pressure signals while being insensitive to residual ventricular function. An incorporated mechanical spring-mass-damper assembly affects the passive response to optimize the dynamic interaction between the prototype and the supported cardiovascular system. It was found that increasing the damping from a medium to a high level was effective in filtering out the higher frequency ventricular pressure signals, reducing a modified amplitude ratio by up to 72%. A spring response was also identified as being inherent in the passive response and was characterized as being highly nonlinear at the extremes of the floating assembly's translation range. The results from this study introduce a new means of BiVAD control as well as the characterization of a fully passive mechanical physiological controller. © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Gaddum N.R.,Queensland University of Technology | Timms D.L.,Critical Care Research Group | Pearcy M.J.,Queensland University of Technology
Artificial Organs | Year: 2010

Clinical studies have reported the balancing of pump outputs to be a serious control issue for rotary biventricular support (BiVS) systems. Poor reliability of long-term, blood immersed pressure sensors encouraged the development of a new control strategy to improve their viability. A rotary BiVS device was designed and constructed with a mechanical passive controller to autoregulate pump outputs to emulate the native baroreceptor response. In vitro testing in a dual circuit, hydraulic mock circulation loop showed that the prototype was able to maintain arterial pressures when subjected to sudden induced hemodynamic destabilization. However, inlet suction was observed when sudden simulated hypertension briefly reduced venous return to the cannulated ventricle. The results have encouraged further development of the device as a means to create an inherently stable, fully passive biventricular support device. © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Moore J.P.R.,University of Queensland | Moore J.P.R.,Critical Care Research Group | Dyson A.,University College London | Singer M.,University College London | And 2 more authors.
British Journal of Anaesthesia | Year: 2015

Cardiovascular resuscitation is a cornerstone of critical care practice. Experimental advances have increased our understanding of the role of the microcirculation in shock states and the development of multi-organ failure. Strategies that target the microcirculation in such conditions, while theoretically appealing, have not yet been shown to impact upon clinical outcomes. This review outlines the current understanding of microcirculatory dysfunction in septic, cardiogenic, and hypovolaemic shock and outlines available treatments and strategies with reference to their effects upon the microcirculation. © 2015 The Author.

Moore J.P.R.,Critical Care Research Group | Fraser J.F.,Critical Care Research Group
Annals of Thoracic Surgery | Year: 2010

Cardiac tamponade is defined as a life-threatening, slow or rapid compression of the heart due to the pericardial accumulation of fluid, pus, thrombus or gas as a result of effusion, trauma, or myocardial rupture. We describe the case of a lady who developed classic signs of cardiac tamponade immediately after an open hiatus hernia repair. Computed tomographic imaging revealed extrapericardial hernia recurrence causing cardiac compression. We believe this is the first such reported case. We conclude that cardiac tamponade from acute recurrence of hiatus hernia must be considered in the unstable postoperative patient and that the definition of cardiac tamponade is expanded to include extrapericardial pathologies. © 2010 The Society of Thoracic Surgeons.

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