Papers by Kiran Dellimore
2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015
Dehydration resulting from acute diarrhea is one of the leading causes of infant mortality in the... more Dehydration resulting from acute diarrhea is one of the leading causes of infant mortality in the developing world. Safe assessment of an infant's hydration level is essential to determine appropriate clinical intervention strategies. However, clinical hydration scales, which are the current gold standard for non-invasive hydration assessment, are often unreliable in lower resource settings. This study presents the development and testing of non-invasive, optical sensors for the objective assessment of dehydration based on the quantitative measurement of skin recoil time, capillary refill time and skin temperature. The results obtained have demonstrated the basic feasibility of using optical sensors for the objective assessment of dehydration. However, several challenges must be overcome before these sensors can be applied in a clinical setting.
2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015
The clinical assessment of dehydration is highly subjective and requires experienced and highly t... more The clinical assessment of dehydration is highly subjective and requires experienced and highly trained clinical personnel. At present no objective method for quantitatively determining an individual's dehydration status exists. The aim of this study is to address this deficiency by presenting the development and testing of a novel diagnostic tool for dehydration detection based on infrared spectrometry. Laboratory testing and two clinical studies were conducted to evaluate the efficacy of the device in both adults and infants. The results were promising for the infant study with a clear trend exhibited. However, a number of challenges must be overcome before this sensor can be applied in a clinical setting.
2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015
Pulse detection via palpation is a basic and essential procedure in daily medical practice. We ha... more Pulse detection via palpation is a basic and essential procedure in daily medical practice. We have been investigating the performance of a single accelerometer placed above the carotid artery, which is one of the recommended locations for manual palpation. A low-cost sensor attached by an adhesive measures accelerations due to carotid dilatations and whole body vibrations. A real-time demonstrator has been developed to classify 10 second- windows in "Pulse", "Motion" and "No Pulse" and to infer pulse rate. Data were obtained during a scheduled head-up tilt table test (HUTT). Our results show for a subgroup of 10 patients with acute hypotension a wide spread of "good" signal coverage ranging from as low as 37% up to 100%. Key factors compromising the performance in HUTT are motion artifacts, arrhythmias, sensor placement and sensor-skin coupling. In conclusion, pulse detection with a single accelerometer is sufficiently accurate, if good signal coverage can be achieved.
The performance of a 19 mm diameter prosthetic aortic valve at a heart rate of 72bpm was investig... more The performance of a 19 mm diameter prosthetic aortic valve at a heart rate of 72bpm was investigated during systole, through fluid-structure interaction simulations using four different leaflet skin friction coefficients (0.0, 9.24x10 -4 , 4.80x10 -2 and 4.80x10 -1 ). The numerical predictions were validated against experimental data for the systolic transvalvular pressure gradient (STVPG) and yielded reasonable qualitative and quantitative agreement (rms error < 13% in all cases). Increasing the leaflet skin friction was found to increase the magnitude of the STVPG, increase the peak velocity and decrease the valve orifice area when the leaflets were fully open, which are consistent with the effects of calcific stenosis. However, the results for the leaflet dynamics during opening and closing were inconsistent with expectation since increasing the leaflet skin friction decreased rapid valve closing time and had a negligible effect on the ejection time and rapid valve opening time. The deficiencies in the numerical predictions may be attributed to the use of a constant leaflet elastic modulus in the simulations.
Resuscitation, 2014
ABSTRACT Objectives To evaluate the performance of a real-time feedback algorithm for chest compr... more ABSTRACT Objectives To evaluate the performance of a real-time feedback algorithm for chest compression (CC) during cardiopulmonary resuscitation (CPR), which provides accurate estimation of the CC depth based on dual accelerometer signal processing, without assuming full CDC. Also, to explore the influence of incomplete chest decompression (CDC) on the CC depth estimation performance. Methods The performance of a real-time feedback algorithm for CC during CPR was evaluated by comparison with an offline algorithm using adult CPR manikin CC data obtained under various conditions. Results The real-time algorithm, using non-causal baselining, delivered comparable CC depth estimation accuracy to the offline algorithm on both soft and hard back support surfaces. In addition, for both algorithms incomplete CDC led to underestimation of the CC depth. Conclusions CPR feedback systems which utilize an assumption of full CDC may be unreliable especially in long duration CPR events where rescuer fatigue can strongly influence CC quality. In addition, these systems may increase the risk of thoracic and abdominal injury during CPR since rescuers may apply excessive compression forces due to underestimation of the CC depth when incomplete CDC occurs. Hence, there is a strong need for CPR feedback systems to accurately measure CDC in order to improve their clinical effectiveness.
Accurate specification of the drag coefficient, considering the influence of turbulence, is impor... more Accurate specification of the drag coefficient, considering the influence of turbulence, is important in correctly predicting the air-water flow in a stirred tank. Multiphase CFD simulations in a laboratory-scale Rushton-turbine flotation tank were performed to explore the effects of four different drag coefficient correlations which were implemented in the CFD solver via user defined functions. An Eulerian-Eulerian multiphase approach with the dispersed k- turbulence model was used to predict the gas holdup under turbulent and laminar flow conditions. Comparison of the gas holdup predictions obtained by different drag coefficient correlations showed that the choice of drag coefficient formulation significantly contributes to improving the accuracy of numerical predictions in each flow regime. The results also suggest that further improvement in the CFD simulation of stirred tanks can be achieved by better quantification of the turbulent properties associated with the interfacial f...
• Aortic valve stenosis affects ~20% of the elderly population • Accounts for >200k surgical homo... more • Aortic valve stenosis affects ~20% of the elderly population • Accounts for >200k surgical homograft & prosthetic aortic valve replacements annually, worldwide Motivation 7/28/2013 3/14 7/28/2013 4/14 Previous Work 7/28/2013 5/14 Skin Friction Clark (1977)-Found flow surfaces of calcified valve may be hydraulically rough due to calcium deposition which can lead to increased turbulence levels within the valve. Bernacca et al. (1995,1997)-Showed calcification will most likely occur at areas where high stress is present. These are the areas where leaflet failure is most likely to happen. FSI Simulations De Hart et al. (2002)-FSI analysis of a fiber-reinforced stentless aortic valve during systole. Showed aortic root compliance greatly influences valve opening and closing dynamics. Carmody et al. (2006)-Used FSI simulations to study impact of leafletblood flow interaction on tri-leaflet aortic valve operation. Found strong interaction between valve leaflets and blood flow during opening and closing. Nobili et al. (2008)-Performed FSI simulations of a mechanical bileaflet aortic valve. Accurately predicted leaflet opening and closing dynamics and the STVPG. Noted strong coupling between leaflet movement and blood flow.
44th AIAA Aerospace Sciences Meeting and Exhibit, 2006
Cardiovascular Engineering and Technology, 2014
42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2006
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014
Neurally mediated syncope (NMS) is a disorder of the autonomic regulation of postural tone, which... more Neurally mediated syncope (NMS) is a disorder of the autonomic regulation of postural tone, which is characterized by hypotension and/or bradycardia, resulting in cerebral hypo-perfusion and finally in a sudden loss of consciousness. Prediction of an impending NMS requires detection of pulse presence to derive heart rate (HR) as well as to assess the pulse strength (PS) related to systolic blood pressure (SBP) preferably from a single body location only. This paper analyses the basic feasibility of using a single accelerometer positioned above the common carotid artery to assess pulse strength and pulse rate towards NMS prediction. A physical model has been investigated to gain insights into expected signal morphologies and potential feature candidates vs. hemodynamic parameters such as SBP, pulse pressure (PP) and PR relevant for NMS detection. Model results are compared with first measurements obtained in a head-up tilt table test (HUTT) from a patient during impending syncope. We...
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2013
The quality of cardiopulmonary resuscitation (CPR) is often inconsistent and frequently fails to ... more The quality of cardiopulmonary resuscitation (CPR) is often inconsistent and frequently fails to meet recommended guidelines. One promising approach to address this problem is for clinicians to use an active feedback device during CPR. However, one major deficiency of existing feedback systems is that they fail to account for the displacement of the back support surface during chest compression (CC), which can be important when CPR is performed on a soft surface. In this study we present the development of a real-time CPR feedback system based on an algorithm which uses force and dual-accelerometer measurements to provide accurate estimation of the CC depth on a soft surface, without assuming full chest decompression. Based on adult CPR manikin tests it was found that the accuracy of the estimated CC depth for a dual accelerometer feedback system is significantly better (7.3% vs. 24.4%) than for a single accelerometer system on soft back support surfaces, in the absence or presence ...
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
When performing cardiopulmonary resuscitation (CPR) it is important that adequate back support is... more When performing cardiopulmonary resuscitation (CPR) it is important that adequate back support is given to the patient in order to allow the medical practitioner to produce an appropriate technique during chest compression (CC). The current study investigates how backboard configuration (i.e., orientation and size) impact compression stiffness during CPR using a torso CPR training manikin. The effect of backboard size on CC performance during CPR was found to be significant with the 94.8% larger backboard producing an increase in compression stiffness of as much as 62.7% relative to the smaller backboard. The impact of backboard orientation was also found to be important with a longitudinal orientation producing an increase in compression stiffness of as much as 60.3% relative to a latitudinal orientation. Backboard configuration should be considered by clinicians when trying to achieve optimal CC performance during CPR in hospital settings.
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Papers by Kiran Dellimore