Postoperative delirium after major orthopedic surgery.

BACKGROUND: Postoperative delirium (POD) is one of the most common complications in older adult patients undergoing elective surgery. Few studies have compared, within the same institution, the type of surgery, risk factors and type of anesthesia and analgesia associated with the development of POD. AIM: To investigate the following three questions: (1) What is the incidence of POD after non-ambulatory orthopedic surgery at a high-volume orthopedic specialty hospital? (2) Does surgical procedure influence incidence of POD after non-ambulatory orthopedic surgery? And (3) For POD after non-ambulatory orthopedic surgery, what are modifiable risk factors? METHODS: A retrospective cohort study was conducted of all non-ambulatory orthopedic surgeries at a single orthopedic specialty hospital between 2009 and 2014. Patients under 18 years were excluded from the cohort. Patient characteristics and medical history were obtained from electronic medical records. Patients with POD were identified using International Classification of Diseases, 9th Revision (ICD-9) codes that were not present on admission. For incidence analyses, the cohort was grouped into total hip arthroplasty (THA), bilateral THA, total knee arthroplasty (TKA), bilateral TKA, spine fusion, other spine procedures, femur/pelvic fracture, and other procedures using ICD-9 codes. For descriptive and regression analyses, the cohort was grouped, using ICD-9 codes, into THA, TKA, spinal fusions, and all procedures. RESULTS: Of 78492 surgical inpatient surgeries, the incidence from 2009 to 2014 was 1.2% with 959 diagnosed with POD. The incidence of POD was higher in patients undergoing spinal fusions (3.3%) than for patients undergoing THA (0.8%); THA patients had the lowest incidence. Also, urgent and/or emergent procedures, defined by femoral and pelvic fractures, had the highest incidence of POD (7.2%) than all other procedures. General anesthesia was not seen as a significant risk factor for POD for any procedure type; however, IV patient-controlled analgesia was a significant risk factor for patients undergoing THA [Odds ratio (OR) = 1.98, 95% confidence interval (CI): 1.19 to 3.28, P = 0.008]. Significant risk factors for POD included advanced age (for THA, OR = 4.9, 95%CI: 3.0-7.9, P \u3c 0.001; for TKA, OR = 2.16, 95%CI: 1.58-2.94, P \u3c 0.001), American Society of Anesthesiologists score of 3 or higher (for THA, OR = 2.01, 95%CI: 1.33-3.05, P \u3c 0.001), multiple medical comorbidities, hyponatremia (for THA, OR = 2.36, 95%CI: 1.54 to 3.64, P \u3c 0.001), parenteral diazepam (for THA, OR = 5.05, 95%CI: 1.5-16.97, P = 0.009; for TKA, OR = 4.40, 95%CI: 1.52-12.75, P = 0.007; for spine fusion, OR = 2.17, 95%CI: 1.19-3.97, P = 0.01), chronic opioid dependence (for THA, OR = 7.11, 95%CI: 3.26-15.51, P \u3c 0.001; for TKA, OR = 2.98, 95%CI: 1.38-6.41, P = 0.005) and alcohol dependence (for THA, OR = 5.05, 95%CI: 2.72-9.37, P \u3c 0.001; for TKA, OR = 6.40, 95%CI: 4.00-10.26, P \u3c 0.001; for spine fusion, OR = 6.64, 95%CI: 3.72-11.85, P \u3c 0.001). CONCLUSION: POD is lower (1.2%) than previously reported; likely due to the use of multi-modal regional anesthesia and early ambulation. Both fixed and modifiable factors are identified

A note about isothermic surfaces in Rn−j,j

In this note we survey our results on the description of ti-melike isothermic surfaces in Rn-j,j using the Grassmannian systems or U/K-systems. We give the natural extensions of the definition of Ribaucour and Darboux transformations for timelike isothermic surfaces and review how those transformations correspond to dressing actions of suitable simple elements.      &nbsp

A proposed model for frequency tuned antennas used in mobile communication systems

The antenna is considered as one of the most fundamental elements in wireless communication systems, especially in mobile devices. Desirable specifications of antennas include covering wide range of operating frequencies, while maintaining high quality of system performance over the whole range of operating frequencies. Therefore, the ability of tuning the resonant frequency of the antenna without altering its physical dimensions would be highly recommended in up-and-coming designs of antennas in mobile devices. This research work proposes a model for tuning the operating frequency of the inverted F-antenna over a reasonably wide range of frequencies, via altering the electromagnetic properties of its ferrite material. In this proposed model, it will be shown that the electronic control of the permeability of the ferrite material of the antenna leads effectively to a significant shift in its resonant frequency, and hence to an overall improvement in the performance of the communication system

Exploration the extrudability of aluminum matrix composite (LM6/TIC) through modeling, simulation and experimental process

Aluminum matrix composites (LM6/TiC) is a mix of excellent properties of aluminum casting alloy (LM6), and particles of (TiC) which make it the first choice in many applications like airplane and marine industries. During this research the extrudability and mechanical specifications of this composite (LM6/TiC) are investigated before and after extrusion theoretically and experimentally. In this research; ABAQUS/CAE software has been successfully employed for Modeling and simulation the extrusion process before experiments in order to predict any error before fabrication. The experimental works includes design and fabrication the extrusion mold. The extruded parts are test by (SEM) to show the microstructure properties. Simulation results indicate the positions of stresses concentration (Mises stresses), and also the velocity of dislocation elements during extrusion. Experimental results show that, many mechanical properties are improved and enhanced after extrusion like stiffness and wear resistance. The microstructure test show that, the addition of (5%) wt. of (TiC) particulate with (T6) heat treatment (treating the solution in (525°C) and then ageing for (8) h at 180 °C) to the master alloy (LM6) will improve the strength about more than (15%) comparing with original matrix (LM6). Comparison between theoretical and practical results before and after extrusion indicates significant improvements after adding (TiC) particulates. This improvement is due to the high interference and bonding forces between the master alloy and composite particulates, which result in a fine grain size after the process. Keywords: Aluminum, Extrusion, Composite, TiC, LM6

On the reduction of the degree of linear differential operators

Let L be a linear differential operator with coefficients in some differential field k of characteristic zero with algebraically closed field of constants. Let k^a be the algebraic closure of k. For a solution y, Ly=0, we determine the linear differential operator of minimal degree M and coefficients in k^a, such that My=0. This result is then applied to some Picard-Fuchs equations which appear in the study of perturbations of plane polynomial vector fields of Lotka-Volterra type

747-6 Myocardial Blood Flow in Aortic Regurgitation: Comparison of Global and Regional Blood Flow to Regional Wall Stresses

The impact of regional wall stress (WS) abnormalities on regional coronary flow (CBF) in aortic regurgitation (AR) is not known. However, the existence of such a relation is of potential importance since it might account in part for LV dysfunction and myocardial fibrosis seen in AR, and could suggest therapeutic strategies. We have previously developed and validated a method for calculating regional WS in the radial, circumferential and meridional directions from mid wall (MW) to apex (AP) and endocardium (ENDO) to epicardium (EPI) using a 4000 element model of the LV To define the relation of regional WS and CSF in AR, we applied our LV model in 5 normal (NL) and 4 AR rabbits in which regional CBF was measured using fluorescent microspheres. CBF and radial WS were as follows:CBF (ml/min/gm)Radial WS (×103dynes/cm2)MWAPMWAPNLEPI2.491.308329*ENDO2.090.74133133*AREPI1.821.82*8638*ENDO1.410.77*133133**=p<0.001 (EPI vs ENDO for CSF, EPI to ENDO gradient in AR vs NL for radial WS)Thus, in AR, transmural CBF distribution varies significantly at the apex, while this tendency is less marked and less consistent in NL. No discernable transmural variation was apparent elsewhere in either group. These differences paralleled inversely the transmural variations in radial WS in AR vs NL. In contrast, meridional WS and circumferential WS were uniformly and significantly higher in AR than NL at apex and base (all p < 0.001), a pattern which bore no relation to regional CSF pattern. Thus, regional radial WS influences regional transmural CBF pattern in AR. The importance of this relation to regional LV function and regional myocardial fibrosis in AR now must be assessed

Fast upsetting of circular cylinders of aluminium metal matrix composites: experimental results and numerical analysis

Cylindrical specimens of Al/Cu and Al/Li metal matrix composite (MMC) were subjected to dynamic compression at room temperature using an experimental drop hammer. Force-time and displacement-time traces were recorded. The experimental results are compared with theoretical results obtained using finite-difference analysis proposed in a previous paper by the authors [1]. The computational results obtained for the force-time histories agree reasonably with the experimental observation. Effect of strain rate and thermal softening on the mechanical behaviour of Al/Cu MMC and Al/Li MMC were examined

Bjorling Problem for Timelike Surfaces in the Lorentz-Minkowski Space

We solve the Bjorling problem for timelike surfaces in the Lorentz-Minkowski space through a split-complex representation formula obtained for this kind of surface. Our approach uses the split-complex numbers and natural split-holomorphic extensions. As applications, we show that the minimal timelike surfaces of revolution as well as minimal ruled timelike surfaces can be characterized as solutions of certain adequate Bjorling problems in the Lorentz-Minkowski space