Technology and Health Care - Volume 16, issue 2

Authors: Marti, Florian | Blunschi, Nadine | Leippold, Thomas | Müller, Bert

Article Type: Research Article

Abstract: A simulation system that generates dynamic bladder pressures for the use of testing and examining artificial urinary sphincters is designed, implemented, and compared to in-vivo measurements of Valsalva and coughing profiles. Cylinder and piston, which are integrated into the universal testing machine, simulating the bladder are connected with explanted sow urethras. The AMS 800™ artificial urinary sphincter closes the urethra with well-defined external pressures. In order to select appropriate profiles for the bladder pressure, 34 Valsalva and coughing profiles of 6 patients were evaluated with respect to amplitude, pressure raise, dwell time, and half width.

Keywords: Artificial urinary sphincter, bladder simulation, cough profiles, cough profiles simulation, valsalva pressure, valsalva profiles simulation

DOI: 10.3233/THC-2008-16201

Citation: Technology and Health Care, vol. 16, no. 2, pp. 77-83, 2008

Authors: Thorey, Fritz | Stukenborg-Colsman, Christina | Windhagen, Henning | Wirth, Carl Joachim

Article Type: Research Article

Abstract: Today the use of pneumatic tourniquet is commonly accepted in total knee arthroplasty (TKA) to reduce perioperative blood loss. There are a few prospective randomised and nonrandomised studies that compare the effect of tourniquet release timing in cementless or cemented unilateral TKA. However, many of these studies show an inadequate reporting and methodology. This randomized prospective study was designed to investigate the efficiency of tourniquet release timing in preventing perioperative blood loss in a simultaneous bilateral TKA study design. To our knowledge, this is the first study of its kind, in which the effect of tourniquet release timing on perioperative …blood loss was investigated in simultaneous bilateral cemented TKA to compare both techniques intraindividually. In 20 patients (40 knees) one knee was operated with tourniquet release and hemostasis before wound closure, and the other knee with tourniquet release after wound closure and pressure dressing. We found no significant difference in total blood loss between both techniques (p=0.930), but a significant difference in operating time (p=0.035). There were no postoperative complications at a follow-up of 6 month. Other studies report an increase the blood loss in early tourniquet release and an increase the risk of early postoperative complications in deflation of tourniquet after wound closure. In this study we found no significant difference in perioperative blood loss and no increase of postoperative complications. Therefore, we recommend a tourniquet release after wound closure to reduce the duration of TKA procedure and to avoid possible risks of extended anaesthesia. Show more

Keywords: Perioperative blood loss, cemented TKA, tourniquet release, bilateral

DOI: 10.3233/THC-2008-16202

Citation: Technology and Health Care, vol. 16, no. 2, pp. 85-92, 2008

Authors: Haasper, Carl | Breitbart, Astrid | Hankemeier, Stefan | Wehmeier, Michael | Hesse, Eric | Citak, Musa | Krettek, Christian | Zeichen, Johannes | Jagodzinski, Michael

Article Type: Research Article

Abstract: For tissue engineering of bone, a carrier matrix and efficient cell seeding are desirable. This study analysed the effect of fibrin glue on bone marrow stromal cells (BMSC) adhesion, proliferation (MTS-Test), differentiation (alkaline phosphatase (AP), osteocalcin (OC), ELISA) and compared the results with cells seeded within culture media on a decellularized, xenogenic bone matrix. There was no significant difference regarding cell adhesion. Proliferation after one week was significantly increased without fibrin glue. AP was increased in both groups when compared with porous scaffolds without cells. OC secretion was increased under both seeding conditions. Microscopic investigation of the …cells with fibrin-glue showed less cell-cell contacts. This study reveals that cell seeding with medium demonstrates similar adherence rates compared with fibrin glue. Fibrin glue significantly decreases cell proliferation. Cell differentiation with respect to ALP and OC is not affected. Further studies are required to assess the long term and in vivo effects of both methods with respect to BMSC viability and differentiation. Fibrin sealants seem not necessary to achieve cell adherence when using a porous bone matrix. Show more

Keywords: Tissue engineering, bone, fibrin glue, cell culture

DOI: 10.3233/THC-2008-16203

Citation: Technology and Health Care, vol. 16, no. 2, pp. 93-101, 2008

Authors: Thomas, Neal J. | Ramnarayan, Padmanabhan | Bell, Michael J. | Maheshwari, Prabhat | Wilson, Shaun | Nazarian, Emily B. | Phipps, Lorri M. | Stockwell, David C. | Engel, Michael | Maffei, Frank A. | Vyas, Harish G. | Britto, Joseph

Article Type: Research Article

Abstract: Improving diagnostic accuracy is essential. The extent of diagnostic uncertainty at patient admission is not well described in critically ill children. Therefore, we studied the extent that pediatric trainee diagnostic performance could be improved with the aid of a computerized diagnostic tool. Data regarding patient admissions to five Pediatric Intensive Care Units were collected. Information included patients' clinical details, admitting team's diagnostic workup and discharge diagnosis. An attending physician assessed each case independently and suggested additional diagnostic possibilities. Diagnostic accuracy was calculated using the discharge diagnosis as the gold standard. 206 out of 927 patients (22.2%) admitted to the PICUs …did not have an established diagnosis at admission. The trainee teams considered a median of three diagnoses in their workup (IQR 3–5) and made an accurate diagnosis in 89.4% cases (95% CI 84.6%–94.2%). Diagnostic accuracy improved to 92.5% with use of the diagnostic tool alone, and to 95% with the addition of attending physicians' diagnostic suggestions. We conclude that a modest proportion of admissions to these PICUs were characterized by diagnostic uncertainty during initial assessment. Although there was a relatively high accuracy rate of initial assessment in our clinical setting, it was further improved by both the diagnostic tool and the physicians' diagnostic suggestions. It is plausible that the tool's utility would be even greater in clinical settings with less expertise in critical illness assessment, such as community hospitals, or emergency departments of non-training institutions. The role of diagnostic aids in the care of critically ill children merits further study.further study. Show more

Keywords: Diagnosis, diagnostic reminder system, internet, pediatrics

DOI: 10.3233/THC-2008-16204

Citation: Technology and Health Care, vol. 16, no. 2, pp. 103-110, 2008

Authors: Demiris, George | Oliver, Debra Parker | Dickey, Geraldine | Skubic, Marjorie | Rantz, Marilyn

Article Type: Research Article

Abstract: The aim of this paper is to present a participatory evaluation of an actual “smart home” project implemented in an independent retirement facility. Using the participatory evaluation process, residents guided the research team through development and implementation of the initial phase of a smart home project designed to assist residents to remain functionally independent and age in place. We recruited nine residents who provided permission to install the technology in their apartments. We conducted a total of 75 interviews and three observational sessions. Residents expressed overall positive perceptions of the sensor technologies and did not feel that these interfered with …their daily activities. The process of adoption and acceptance of the sensors included three phases, familiarization, adjustment and curiosity, and full integration. Residents did not express privacy concerns. They provided detailed feedback and suggestions that were integrated into the redesign of the system. They also reported a sense of control resulting from their active involvement in the evaluation process. Observational sessions confirmed that the sensors were not noticeable and residents did not change their routines. The participatory evaluation approach not only empowers end-users but it also allows for the implementation of smart home systems that address residents' needs. Show more

Keywords: Participatory evaluation, sensors, smart home, long term care facility, aging in place

DOI: 10.3233/THC-2008-16205

Citation: Technology and Health Care, vol. 16, no. 2, pp. 111-118, 2008

Authors: Karmonik, Christof | Klucznik, Richard | Benndorf, Goetz

Article Type: Research Article

Abstract: Objective: Computational Fluid Dynamic (CFD) is increasingly being used for modeling hemodynamics in intracranial aneurysms. While CFD techniques are well established, need for validation of the results remains. By quantifying features in velocity patterns measured with 2D phase contrast magnetic resonance (pcMRI) in vivo and simulated with CFD, the role of pcMRI for providing reference data for the CFD simulation is explored. Methods: Unsteady CFD simulations were performed with inflow boundary conditions obtained from 2D pcMRI measurements of an aneurysm of the anterior communication artery. Intra-aneurysmal velocity profiles were recorded with 2D pcMRI and calculated with CFD. Relative …areas of positive and negative velocity were calculated in these profiles for maximum and minimum inflow. Results: Areas of positive and of negative velocity similar in shape were found in the velocity profiles obtained with both methods. Relative difference in size of the relative areas for the whole cardiac cycle ranged from 1%–25% (average 12%). Conclusion: 2D pcMRI is able to record velocity profiles in an aneurysm of the anterior commuting artery in vivo. These velocity profiles can serve as reference data for validation of CFD simulations. Further studies are needed to explore the role of pcMRI in the context of CFD simulations. Show more

Keywords: Cerebral aneurysms, hemodynamics, computational fluid dynamics, phase contrast magnetic resonance imaging

DOI: 10.3233/THC-2008-16206

Citation: Technology and Health Care, vol. 16, no. 2, pp. 119-128, 2008

Authors: Thorey, Fritz | Richter, Arne | Besdo, Silke | Hackenbroich, Christian | Meyer-Lindenberg, Andrea | Hurschler, Christof | Windhagen, Henning

Article Type: Research Article

Abstract: To manage fractures in long bones, intramedullar implants, plates or external fixators are often used. In many cases, the implants are removed after bone consolidation. X-ray images are normally used to monitor bone formation and to determine the point of return to full load bearing and removal of the implants. However, plain radiographs give only inaccurate information about the degree of healing progress. Known quantitative methods as QCT, DEXA, etc. provide information about bone density which certainly contributes to the mechanical properties of healing bone, but they do not provide a direct measurement of the stiffness of the healing callus. …In this study we present an in vivo 4-point-bending stiffness device for small animals which is designed to directly monitor the progression of the healing process. The device was tested in a bone-defect model with different test-specimens chosen to simulate the stiffness of bone at different stages of healing. To verify the results, it was tested in an animal fracture study in rabbits during the healing period with and without an intramedulary implant. Both the test-specimen and bones of the in vivo study were compared with data in a materials testing system (MTS) in four-point bending. The device was found to have a high precision and significant in vitro and in vivo correlation with the MTS. The results suggest that this measurement device has the ability to monitor the healing process of bone and to analyse the influence of degradable implants on the mechanical behaviour of bone or bone metabolism effecting pharmaceutics. Show more

Keywords: Fracture healing, in vivo monitoring, bone healing, small animal models, mechanical properties

DOI: 10.3233/THC-2008-16207

Citation: Technology and Health Care, vol. 16, no. 2, pp. 129-140, 2008

Authors: Gefen, Amit

Article Type: Research Article

Abstract: Pressure-related deep tissue injury (DTI) is a severe form of pressure ulcer that initiates in compressed muscle tissues under bony prominences, and progresses superficially towards the skin. Patients with impaired motosensory capacities are at high risk of developing DTI. There is a critical medical need for developing risk assessment tools for DTI. A new anatomical index, the Compression Intensity Index: CII=(BW/Rt)1/2 , which depends on the body weight (BW), radius of curvature of the ischial tuberosities (R) and thickness of the underlying gluteus muscles (t), is suggested for approximating the loading intensity in muscle tissue during sitting in permanent wheelchair …users, as part of a clinically-oriented risk assessment for DTI. Preliminary CII data were calculated for 6 healthy and 4 paraplegic subjects following MRI scans, and data were compared between the groups and with respect to a gold standard, being a previously developed subject-specific MRI-finite-element (MRI-FE) method of calculating muscle tissue stresses (Linder-Ganz et al., J. Biomech. 2007). Marked differences between the R and t parameters of the two groups caused the CII values of the paraplegics to be ∼ 1.6-fold higher than for the healthy (p<0.001), thereby indicating on the sensitivity of this parameter to the pathoanatomical changes that occur in the buttocks with paraplegia. Data of CII correlated reasonably with the gold standard calculations of MRI-FE muscle stresses (correlation coefficient 0.65). Since CII measurements do not require highly-specialized biomechanical numerical analyses such as MRI-FE, CII has the potential to serve as a practical, quick, and cost-effective approximation of the loading intensity in muscles of wheelchair-bound or bedridden patients. Hence, CII measurements can be integrated into DTI-risk-assessment tools, the need of which is now being discussed intensively in the American and European Pressure Ulcer Advisory Panel meetings. Show more

Keywords: Pressure ulcer, decubitus, bed sore, analytical model, contact mechanics

DOI: 10.3233/THC-2008-16208

Citation: Technology and Health Care, vol. 16, no. 2, pp. 141-149, 2008