Perioperative risk factors affecting hospital stay and hospital costs in open heart surgery for patients > or = 65 years old

OBJECTIVE: Demographic changes, associated with increased demands for open heart surgery in the elderly, place increased burden on financial resources. To evaluate perioperative risk factors affecting incidence of hospital events and estimation of hospital charges, 2577 patients > or = 65 years (range 65-91), operated on from January 1991 to December 1994, were compared with a concurrent cohort of 2642 younger patients. METHODS: Statistical analysis, by surgical procedure, focused on hospital mortality, key postoperative complications affecting length of hospital stay and hospital charges. RESULTS: Overall hospital mortality was 4.7%, 3.5% in younger patients versus 6.1% in the older group (P < 0.01). Mortality was significantly lower in patients less than 65 years undergoing coronary artery bypass grafting (3% versus 5%, P < 0.01) and valve replacement (4% versus 9%, P = 0.01). Significant risk factors for hospital death in the elderly: diabetes (P < 0.01), hypertension (P < 0.01), myocardial infarction (P < 0.01) and congestive heart failure (P < 0.01). Significant postoperative events, more common in older patients, included prolonged ventilation (P < 0.01), congestive heart failure (P < 0.01), infection (P < 0.01), cerebrovascular accident (P < 0.01), and intra aortic balloon pump (P < 0.01). Incremental risk factors for morbidity in the elderly were: higher New York Heart Association class, congestive heart failure, emergent operation, and female gender. Mean length of hospital stay for the < 65 group was 15.3 versus > 19.5 days for the > 65 group (P < 0.01). Length of stay over 18 days positively correlated with increased morbidity in both age groups. For patients > or = 65 years of age, the average hospital charge for open heart surgery was 172% higher for patients with a length of stay greater than 18 days compared with 165% for patients less than 65 years of age. CONCLUSIONS: Higher operative mortality and longer length of stay in elderly patients, resulting in increased health care costs, was associated with more co-morbidities. These results suggest interventions designed to reduce congestive heart failure and other co-morbidities may improve patient's recovery and reduce costs.     

An ON-resistance closed form for VDMOS devices

An analytical ON-resistance expression for different designs of VDMOS (vertically diffused metal-oxide-semiconductor) devices which takes into consideration the two-dimensional (2-D) nature of the current flow is obtained. This expression differs from other models that overestimate this resistance for large cell spacings. This formulation is in close agreement with experimental points obtained from the interdigitated fabricated structures and with 2-D simulations. Moreover, the effect of a two-level oxide thickness on the ON resistance has been investigated for the interdigitated case     

SLA-aware operational efficiency in AI-enabled service chains: challenges ahead

Information Systems and e-Business Management - Service providers compose services in service chains that require deep integration of core operational information systems across organizations....     

The modulus of elasticity of high performance concrete

To determine the modulus of elasticity of concrete precisely is very important for structures that require strict control of the deformability. International codes propose a wide variety of formulae which establish a relationship between modulus of elasticity and compressive strength. Most of these codes are valid up to 50 MPa, the usual limit for normal concretes. A research programme has been carried out to establish the modulus of elasticity-compressive strength curve for low and high strength concretes. The effect of the aggregate also has been studied. This is an important factor to take into account, sometimes more important than the concrete strength itself or even age. A model code formula provides good correlation with experiment up to a compressive strength of 120 MPa. Other aggregates not considered for this code have been studied and results given. Also, the influence of age on the modulus of elasticity is discussed.     

Toxicity screening of candidate materials for the fabrication of a bubble oxygenator: A preliminary report

The hazards encountered in the clinical use of medical devices and implants have been referred in this paper to emphasise the need for and relevance of carrying out appropriate toxicological investigations before such items are manufactured and marketed. Different formulations of polyvinyl chloride, low density polyethylene, high density polyethylene and polyester fabric were subjected to various tests to determine their biocompatibility/safety for their eventual use as components in a bubble oxygenator. The test methods together with the results obtained are described and discussed.     

Dynamics of glyphosate and aminomethylphosphonic acid in a forest soil in Galicia, north-west Spain

Residues of the herbicide glyphosate (N-phosphonomethylglicine) and its main metabolite, aminomethylphosphonic acid (AMPA), were determined in a forest soil in north-west Spain, previously treated with 5 and 8 l ha(-1) of glyphosate. Both products were monitored in the solid and liquid soil phases for an 8-week period after the treatment. Soil samples were extracted by KH2PO4. Concentrated extracts and liquid phase samples were derivatized with 9-fluorenylmethyl chloroformate (FMOC) before determination by HPLC using an anion exchange column and spectrofluorometric detection. The treated soil peaked at 6.9 microg g(-1) of glyphosate, whereas soil water samples peaked at 0.74 microg ml(-1) of glyphosate. One month after the treatment, both glyphosate and AMPA concentrations in soil and water samples were almost negligible. AMPA peaked at 0.77 microg ml(-1) in soil water samples. Glyphosate and AMPA exhibited high vertical mobility in the treated soil, quickly reaching high concentrations in subsurface horizons where the degradation is slower.