In vitro strain measurements in cerebral aneurysm models for cyber-physical diagnosis

Background: The development of new diagnostic technologies for cerebrovascular diseases requires an understanding of the mechanism behind the growth and rupture of cerebral aneurysms. To provide a comprehensive diagnosis and prognosis of this disease, it is desirable to evaluate wall shear stress, pressure, deformation and strain in the aneurysm region, based on information provided by medical imaging technologies. Methods: In this research, we propose a new cyber-physical system composed of in vitro dynamic strain experimental measurements and computational fluid dynamics (CFD) simulation for the diagnosis of cerebral aneurysms. A CFD simulation and a scaled-up membranous silicone model of a cerebral aneurysm were completed, based on patient-specific data recorded in August 2008. In vitro blood flow simulation was realized with the use of a specialized pump. A vision system was also developed to measure the strain at different regions on the model by way of pulsating blood flow circulating inside the model. Results: Experimental results show that distance and area strain maxima were larger near the aneurysm neck (0.042 and 0.052), followed by the aneurysm dome (0.023 and 0.04) and finally the main blood vessel section (0.01 and 0.014). These results were complemented by a CFD simulation for the addition of wall shear stress, oscillatory shear index and aneurysm formation index. Diagnosis results using imaging obtained in August 2008 are consistent with the monitored aneurysm growth in 2011. Conclusion: The presented study demonstrates a new experimental platform for measuring dynamic strain within cerebral aneurysms. This platform is also complemented by a CFD simulation for advanced diagnosis and prediction of the growth tendency of an aneurysm in endovascular surgery.

In vitro simulator with numerical stress analysis for evaluation of stent-assisted coiling embolization in cerebral aneurysm treatments

There are several complications associated with Stent-assisted Coil Embolization (SACE) in cerebral aneurysm treatments, due to damaging operations by surgeons and undesirable mechanical properties of stents. Therefore, it is necessary to develop an in vitro simulator that provides both training and research for evaluating the mechanical properties of stents.

Cardiovascular alterations and management

This chapter reviews the support of cardiovascular function in the face of
many compromises to the system. It focuses on two of the most prevalent and fatal diseases affecting the heart: coronary heart disease and heart failure. These diseases are also a common comorbidity in elderly patients admitted to critical care units. The first section on coronary heart disease reviews the pathophysiological concepts of myocardial ischaemia and associated complications, with detailed consideration of the clinical implications, assessment and associated management. Heart failure is discussed in terms of the body’s compensatory mechanisms and the clinical sequelae and associated clinical features of heart failure. Nursing and medical management is outlined including the management of acute exacerbations of heart failure. Finally, other cardiovascular disorders commonly managed in critical care units are reviewed, ranging from other forms of heart failure to hypertensive emergencies and aortic aneurysms. The case study presented at the end of the chapter highlights the key aspects of the management of coronary heart disease and heart failure in patients admitted to critical care units.

Utilising point of care ultrasound for vascular access in haemodialysis

Learning outcomes: On completion of this continuing professional development activity, participants will be able to: • Discuss basic ultrasound principles; • Define the roles and responsibilities of the nurse in point of care ultrasound; • Identify strategies to utilise ultrasound to provide quality cannulation practice; • Identify anatomic structures on an ultrasound picture; • Identify anomalies in the anatomy such as thrombus, stenosis, aneurysm and pseudoaneurysm; • Describe the advantages and disadvantages of using ultrasound for assessment and cannulation; • Enable staff to reflect on their current approaches to assessment and cannulation.