In humans, peak bone mineral density (BMD) is a highly heritable trait and a strong determinant of subsequent osteoporotic fracture risk. To identify the genetic factors responsible for variation in peak BMD, investigators have turned to animal models. In this study we examined the heritability of BMD acquisition and characterized differences in skeletal geometry, histomorphometry, and biomechanical competence between two lines of mice artificially selected for extremes of peak whole body BMD. F 2 progeny from a cross between C57BL/6 and DBA/2 inbred strains was used as the foundation population to develop lines selected for either high or low BMD. Whole body BMD was measured by dual-energy X-ray absorptiometry (DXA). By the third generation of selection, highest-scoring BMD (HiBMD) mice exhibited 14% greater peak BMD than lowest-scoring BMD (LoBMD) mice. The mean realized heritability of peak BMD was 36%.
Peripheral quantitative computed tomography (pQCT) is increasingly used for measurement of cortical bone geometry and density in mice. We evaluated the accuracy of pQCT for area and density measurements of thin-walled aluminum phantoms and mouse femora. Aluminum tubes with varying wall thicknesses and femora from 1- to 6-month-old C3H/HeJ (C3H) and C57B1/6J (B6) mice (average cortical thickness 0.14-0.29 mm) were scanned at 70- or 90-microm resolution. pQCT values of area were compared to optical values determined after sectioning, while pQCT density (vBMD) was compared to solid aluminum density or correlated to bone ash content. For the aluminum phantoms, the error in pQCT area and density depended strongly on wall thickness, and density was consistently underestimated. For mouse femora, threshold values were found that produced zero error in bone area for each strain and age group, although the optimal threshold differed between groups. pQCT vBMD correlated strongly with ash content (r2=0.7), although the regression equations differed between strains and the magnitude of the inter-strain difference in vBMD was fourfold greater than the difference in ash content. This finding suggests that pQCT can overestimate the differences in volumetric mineral density between inbred mouse strains whose bones are of different thickness (e.g., C3H vs. B6). In conclusion, both area and density values obtained by pQCT depend strongly on specimen thickness, consistent with a partial volume averaging artifact. Investigators using pQCT to assess cortical bones in mice should be aware of the potential for cortical thickness-dependent errors.
Over the past 50 years, various shunting procedures involving the peritoneum have been performed for the treatment of hydrocephalus. During placement of the peritoneal portion of the catheter, complications may arise secondary to a lack of direct visualization. We describe a reduced complication rate with laparoscopically-assisted placement of the peritoneal portion of the catheter. A retrospective chart review was performed of seventy-six (76) laparoscopically-assisted cases performed without consideration of prior abdominal surgery or obesity. Subjects ranged in age from 19 to 80 years. Mean operative time was 55.3 minutes. No visceral injuries occurred. To date, no infectious complications have occurred. In 3% of subjects, conversion to an open procedure was necessary after failure to establish pneumoperitoneum. Laparoscopic placement of peritoneal shunts is safe and efficacious. It provides visualization of the distal catheter target. Moreover, it reduces the risk of visceral complications, CSF pseudocysts, or extraperitoneal placement of the catheter. In the future, laparoscopic placement of the peritoneal portion of the catheter may become a standard treatment in those patients requiring placement of a peritoneal catheter.
PURPOSE: A review of the outcomes of patients who received our video-assisted thoracic surgery (VATS) lung lobectomy in 2015 revealed long lengths of stay, inefficient care transitions, and overuse of resources. Focused process redesign offers a proven method for instituting improvement and changes in health care. We sought to use systems process improvement to streamline VATS lobectomies at our institution, and we targeted cost drivers to optimize quality of care and minimize overuse of resources. METHODS: We performed a retrospective review of perioperative practices between January 2015 and March 2016 for patients undergoing VATS lobectomy that helped establish a value stream map, used a granular cost database, and performed real-time analysis. We used an outcomes database, which allowed us to identify cost drivers, practice variability, and rent seeking. We implemented process redesign with constant review and formal value stream reanalysis at 6-month intervals over a 2-year period. RESULTS: We ultimately experienced an overall 187% reduction of time in the operating room (297 v 159 minutes). Our process redesign also resulted in significantly fewer chest x-rays per patient (mean, 6.7 v 2), laboratory draws (100% v 5.7%), and consultations (100% v 5.7%), which resulted in a 234% reduction in mean length of stay (4.4 v 1.88 days) and an overall cost reduction of 40%. These changes did not have a detrimental effect on patient outcomes: pulmonary complications (16.9% v 8.6%), cardiac complications (13.2% v 8.6%), and readmission rates (13.6% v 2.9%) all decreased. CONCLUSION: By using value stream analysis and process redesign methodologies, closely paired with highly granular cost and outcomes data, we were able to achieve significant improvements in patient outcomes and use of resources.
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