Sensorized guidewires with MEMS tri-axial force sensor for minimally invasive surgical applications.

This paper describes the design of a tri-axial microelectromechanical force sensor (FS) that can be mounted on the tip of the guidewire. Piezoresistive silicon nanowires (SiNW) are embedded into a cross cantilever design with a manoeuvrable stylus to allow the detection of force in all directions. The electrical resistance changes in the four SiNWs are used to decode an arbitrary force applied onto the FS. The sensitivity of the device can be improved by two orders of magnitude compared to bulk Si thanks to the giant piezoresistive effects offered by the SiNW. Robustness of the FS is improved due to the novel design by incorporating a mechanical stopper at the tip of the stylus. Finite element analysis (FEM) analysis was used in designing the FS.

Hip fractures in the elderly: the impact of comorbid illnesses on hospitalisation costs.

INTRODUCTION: Hip fractures in the elderly are associated with multiple comorbidities. MATERIALS AND METHODS: We prospectively surveyed and went through all relevant medical records of 70 consecutive patients admitted to Singapore General Hospital following either a cervical or intertrochanteric femoral fracture from late February to May 2004. The total hospitalisation cost for each patient was calculated based on the costs of inpatient care up to the point of discharge. Regression modeling was performed on the 7 commonest age-related conditions (based on our data), to determine the impact of each comorbidity on total costs. RESULTS: The average age of the cohort was 77.24 years. The median length of stay was 13.6 days. In patients without comorbidities, the mean hospitalisation cost was S$9,347.5 +/- 1719.6. With the presence of comorbidities, the mean cost increased to S$11,502.3 +/- 6024.3. In univariate modeling, dementia added the largest amount to total costs [S$5,398; 95% confidence interval (CI), S$1273 to S$9523; P <0.05]. The presence of diabetes (S$758; 95% CI, S$2,051 to S$3,566), hypertension (S$644; 95% CI, S$1,986 to S$3,274) and osteoarthritis (S$915; 95% CI, S$3,721 to S$1,891) did not significantly add to total costs. When controlled for multiple comorbidities, dementia retained its significance in adding to total costs (S$6,178; 95% CI, S$1,795 to S$10,562; P = 0.006). CONCLUSION AND DISCUSSION: Hip fracture patients with comorbidities incurred higher hospitalisation costs. Cost-containment strategies in hip fracture patients should not only examine the number of comorbidities but also the type of disease.

Characteristics of treated hypertension in incident hemodialysis and peritoneal dialysis patients.

BACKGROUND: The treatment of hypertension in dialysis patients is prevalent and poorly characterized. beta-Blockers and calcium channel blockers (CCBs) have been associated with reduced all-cause and cardiovascular mortality. This study describes the treatment of hypertension and assesses the association between mortality and class of antihypertensive medication among a cohort of dialysis patients. METHODS: The US Renal Data System (USRDS) Dialysis Morbidity and Mortality Study Wave II cohort was analyzed. A total of 2,877 patients initiating hemodialysis or peritoneal dialysis in 1996 or 1997 and treated with antihypertensives were included in this analysis. Vital status was followed until November 2000. RESULTS: Calcium channel blockers were prescribed to 70.3% of patients. Only 31.5% and 27.0% of patients with cardiovascular disease were prescribed angiotensin-converting enzyme inhibitors and beta-blockers, respectively. Mono-, double-, triple-, and more than triple-therapy were reported in 48.0%, 36.1%, 13.2%, and 2.7% of the cohort, respectively. In multivariable, fully adjusted models, no individual class of antihypertensives was associated with changes in all-cause mortality. In all patients, nondihydropyridine CCBs (non-DHP CCBs) were associated with a reduced risk of cardiovascular death (hazard ratio, 0.78; 95% confidence interval, 0.62 to 0.97) and among end-stage renal disease patients with preexisting cardiovascular disease, dihydropyridine CCBs (DHP CCBs) and non-DHP CCBs were associated with reduced risk of all-cause and cardiovascular mortality. CONCLUSION: Calcium channel blocker use is widespread among hypertensive dialysis patients. Antihypertensive prescription patterns suggest a lack of consensus regarding treatment of hypertension. Multivariable analysis of associations between antihypertensive class and mortality reveals results of uncertain clinical significance. Hypertension treatment trials in dialysis patients should be performed to appropriately inform treatment decisions.