OBJECTIVES: We compared the effectiveness and cost of percutaneous occlusion using an Amplatzer septal occluder(ASO)(AGA Medical Corp., Golden Valley, innesota) device compared with surgical closure of an ostium secun...OBJECTIVES: We compared the effectiveness and cost of percutaneous occlusion using an Amplatzer septal occluder(ASO)(AGA Medical Corp., Golden Valley, innesota) device compared with surgical closure of an ostium secundum atrial septal defect(ASD II) in Guatemala. BACKGROUND: The percutaneous occlusion of ASD II in first-world nations seems to offer better clinical results and lower cost compared with surgical closure. METHODS: We reviewed the clinical course of 111 patients referred to our institution for closure of isolated ASD II. Successful closure was assessed immediately after the procedures and at 12 months. Actual hospital costs were calculated for every patient who underwent either of the two procedures. RESULTS: Eighty-three patients with ASD II(75% ) were selected for percutaneous occlusion with the ASO device, and the remaining 28 patients(25% ) underwent surgical closure. In the device group, in 72 patients(86.7% ) devices were successfully deployed. At immediate and 12-month follow-up, the complete closure rate was 87.5% (63 of 72 patients) and 97.2% (70 of 71 patients), respectively. In the surgical group, all patients had successful closure immediately after the procedure and at 12 months. Surgical closure offered a 27% cost savings in comparison with percutaneous occlusion(U.S. ＄ 3,329.50± ＄ 411.30 and U.S. ＄ 4,521.03± ＄ 429.71; p< 0.001, respectively). Cost of the device(U.S. ＄ 2,930.00) proved to be the main cause for this difference. CONCLUSIONS: We confirmed the clinical advantages of percutaneous occlusion over surgical closure of ASD II. However, percutaneous occlusion costs were higher compar ed with surgical closure. In Guatemala, where health care resources are limited, ASD II closure with the ASO device did not prove to be cost-effective.展开更多
The effect of the fracture distribution on CO 2 injection into coal seams was studied with a heterogeneous model having dual porosity to represent both the primary medium (the coal matrix) and the secondary medium (th...The effect of the fracture distribution on CO 2 injection into coal seams was studied with a heterogeneous model having dual porosity to represent both the primary medium (the coal matrix) and the secondary medium (the fractures) under variable stress conditions. A numerical generation method and a digital image processing method were used to model the heterogeneous fracture distribution in the coal. The model solutions demonstrate that: (1) the fractures are the main channel for gas flow and their distribution has an important impact on the gas injection rate; (2) the fractures only affect the injection rate of CO 2 into the coal but not the final storage amount; (3) when gas is injected into coal the fractures will first expand and then close due to the changing effective stresses and the adsorption induced swelling of coal grains. This fully coupled dual-porosity model with a heterogeneous fracture distribution provides a way to predict the CO 2 injection into a coal seam.展开更多
文摘OBJECTIVES: We compared the effectiveness and cost of percutaneous occlusion using an Amplatzer septal occluder(ASO)(AGA Medical Corp., Golden Valley, innesota) device compared with surgical closure of an ostium secundum atrial septal defect(ASD II) in Guatemala. BACKGROUND: The percutaneous occlusion of ASD II in first-world nations seems to offer better clinical results and lower cost compared with surgical closure. METHODS: We reviewed the clinical course of 111 patients referred to our institution for closure of isolated ASD II. Successful closure was assessed immediately after the procedures and at 12 months. Actual hospital costs were calculated for every patient who underwent either of the two procedures. RESULTS: Eighty-three patients with ASD II(75% ) were selected for percutaneous occlusion with the ASO device, and the remaining 28 patients(25% ) underwent surgical closure. In the device group, in 72 patients(86.7% ) devices were successfully deployed. At immediate and 12-month follow-up, the complete closure rate was 87.5% (63 of 72 patients) and 97.2% (70 of 71 patients), respectively. In the surgical group, all patients had successful closure immediately after the procedure and at 12 months. Surgical closure offered a 27% cost savings in comparison with percutaneous occlusion(U.S. ＄ 3,329.50± ＄ 411.30 and U.S. ＄ 4,521.03± ＄ 429.71; p< 0.001, respectively). Cost of the device(U.S. ＄ 2,930.00) proved to be the main cause for this difference. CONCLUSIONS: We confirmed the clinical advantages of percutaneous occlusion over surgical closure of ASD II. However, percutaneous occlusion costs were higher compar ed with surgical closure. In Guatemala, where health care resources are limited, ASD II closure with the ASO device did not prove to be cost-effective.
基金supported by the Chinese National Science Foundation (51104147)the Fundamental Research Funds for the Central Universities (2011QNA17)+1 种基金National Basic Research Program of China (2010CB226800)State Key Laboratory for Geo-mechanics and Deep Underground Engineering in China
文摘The effect of the fracture distribution on CO 2 injection into coal seams was studied with a heterogeneous model having dual porosity to represent both the primary medium (the coal matrix) and the secondary medium (the fractures) under variable stress conditions. A numerical generation method and a digital image processing method were used to model the heterogeneous fracture distribution in the coal. The model solutions demonstrate that: (1) the fractures are the main channel for gas flow and their distribution has an important impact on the gas injection rate; (2) the fractures only affect the injection rate of CO 2 into the coal but not the final storage amount; (3) when gas is injected into coal the fractures will first expand and then close due to the changing effective stresses and the adsorption induced swelling of coal grains. This fully coupled dual-porosity model with a heterogeneous fracture distribution provides a way to predict the CO 2 injection into a coal seam.
