Inductive displacement gauge

Strain gauges are often used for the measurement of contractile activity of muscle tissue. In these cases the strain gauge is used as a force measuring device. Because of its stiffness, the strain-gauge-type transducer resists changes in length produced by contraction, and this could cause secondary effects. This paper describes an alternative method to evaluate contractions. Displacement rather than force is measured. The device offers very little resistance to motion and thus does not constrain the tissue. The sensitivity of the transducer is very high. An additional feature is the low cost of the transducer compared to strain-gauge devices.     

In-Line Pipe Device Checking by Short-Period Analysis of Transient Tests

In this paper, the results of laboratory transient tests concerning the interaction between a pressure wave and an in-line device are discussed. Transients are generated by means of a fast and complete closing of an end valve, and pressure measurements are carried out just upstream of the maneuver valve. The main effect of the device on the pressure time-history—hereafter referred to as pressure signal—is a sharp increase caused by the pressure wave reflection. Three experimental setups are considered, in which different in-line devices are installed (i.e., a ball valve, a butterfly valve, and different-sized orifices). The pressure signal is analyzed in the time domain, and a reliable evaluation of the device location is obtained by means of wavelet functions. Furthermore, on the basis of the value of the pressure increase, the status of the device can be determined; experimental results are synthesized in a dimensionless diagram. Finally, criteria for using the obtained results in other pipe systems are discussed.     

桥式双斗轮取料机结构优化改进

宁钢混匀料场桥式双斗轮取料机经过3年多的使用,发现设备故障率偏高,取料能力偏低,严重影响原料的后续作业流程。通过对设备实地调研并结合已有故障分析,发现主要的故障点集中在桥架梁刚度偏低、小车车体变形和料耙结构不合理等几个方面,针对以上几方面存在的问题,结合实际并借鉴已有的成功经验对设备的机构本体进行分析优化、局部进行改型,从根本上提高了设备的工作稳定性和作业能力,极大地减少了设备的维护成本;同时本次改进对该类设备的换代升级有很大的借鉴意义。     

The treatment of osteoarthritis of the knee with pulsed electrical stimulation

OBJECTIVE: The safety and effectiveness of pulsed electrical stimulation was evaluated for the treatment of osteoarthritis (OA) of the knee. METHODS: A multicenter, double blind, randomized, placebo controlled trial that enrolled 78 patients with OA of the knee incorporated 3 primary efficacy variables of patients' pain, patients' function, and physician global evaluation of patients' condition, and 6 secondary variables that included duration of morning stiffness, range of motion, knee tenderness, joint swelling, joint circumference, and walking time. Measurements were recorded at baseline and during the 4 week treatment period. RESULTS: Patients treated with the active devices showed significantly greater improvement than the placebo group for all primary efficacy variables in comparisons of mean change from baseline to the end of treatment (p < 0.05). Improvement of > or = 50% from baseline was demonstrated in at least one primary efficacy variable in 50% of the active device group, in 2 variables in 32%, and in all 3 variables in 24%. In the placebo group improvement of > or = 50% occurred in 36% for one, 6% for 2, and 6% for 3 variables. Mean morning stiffness decreased 20 min in the active device group and increased 2 min in the placebo group (p < 0.05). No statistically significant differences were observed for tenderness, swelling, or walking time. CONCLUSION: The improvements in clinical measures for pain and function found in this study suggest that pulsed electrical stimulation is effective for treating OA of the knee. Studies for longterm effects are warranted.     

Testing of medical devices (author's transl)

The French regulation of medical devices is already old. it gradually begins since 1940 firstly for the need of safety in radiology. In 1952, an Interministerial Commission (Health, Welfare, Defense, Interior, etc.) was instituted for the medical devices approval: the anaesthesiological devices were examinated since 1956. But this regulation is weak because there is no effective penalty. Nevertheless it is efficient: it had allowed the collection of important documents especially in the fields of radiology, anaesthesiology and intensive care, and recently in hemodialysis. During the last ten years all medical devices in this fields were examinated by the French essay laboratories and their performances were registraded. If the compliance of a device is not effective the approval is not gived. For anaesthesiological and intensive care devices, the approval is give, after clinical testing, only for five years. This approval is not renewed if there are complaints about the device during this time. But medical devices are not easy to define and to test. The best definition seems the American one: "There is a new definition of "device". In broad terms, a device is a health-care product that does not achieve any of its principal intended purposes by chemical action within or on the body or by being metabolized. There is specific recognition that a device may diagnose "conditions" that are not necessarily "diseases" (Medical device Amendment, 1976)." The french regulation is of course not perfect: we suffer of a lack of a law on medical device thus this regulation is appliable only if the public health is envolved. Nevertheless a rather good protection of the patients is assured and the efficiency is gradually better as the international exchanges give technical and clinical informations.     

Pharmacokinetics and pharmacodynamic effects of the angiotensin II antagonist valsartan at steady state in healthy, normotensive subjects

The Salford static knee instrument (SSKI) was developed to determine the quantitative assessment of the human knee joint in vivo by utilizing the technique of applied displacement and measurement of resistive load as proposed by Butler et al. (1). The instrument was used in parallel with the device developed by Al-Turaiki (2) which utilized the opposite method of assessment. The objective of the research was to examine which of the two techniques provided the more reliable and accurate method of knee assessment. Fourteen patients with suspected isolated rupture of the anterior cruciate ligament (ACL) were subjected to anterior-posterior drawer testing on both devices. The results showed that each instrument produced results which confirmed the clinical diagnosis by indicating a significant decrease in anterior stiffness when comparing the injured and uninjured knees. [SSKI device (p = 0.000) and Al-Turaiki (2) device (p = 0.002) statistical significant difference testing with Bonferonni Alpha correction p = 0.0125]. The results showed the Salford static knee instrument indicated a 58 per cent decrease in anterior stiffness and the Al-Turaiki (2) device a 35 per cent decrease when comparing the injured and uninjured knees. In conclusion it is suggested that the application of displacement and measurement of load as proposed by Butler et al. (1) may be the most appropriate technique for precise clinical diagnosis of pathological human knee joint instability.     

一种卸料厂自动卸料车密封装置

介绍了一项中国实用新型专利——卸料厂自动卸料车密封装置,是一种专门治理煤炭装卸过程中二次扬尘的新一代除尘装备置以及设备装置的原理、结构和工艺。     

The use of heterologous promoters for adeno-associated virus (AAV) protein expression in AAV vector production

OBJECTIVE: There are few nonproprietary papers addressing the mechanical strength of intramedullary nails; none address the characteristics of the proximal and distal ends of these devices. Our objective was to provide such data. DESIGN: Independent testing of eight femoral intramedullary nail systems at the proximal, middle, and distal regions was undertaken to evaluate strength and flexural rigidity (stiffness). METHODS: Each device, usually a reconstruction nail, was forty-two to forty-six centimeters in length. Four or five nails of each available size (range 9 to 13 millimeters in diameter) were tested for each system. The nails were cut into proximal, middle, and distal thirds. Each nail section was loaded to failure using a four-point bend test on a custom fixture (modification of the American Society of Testing Materials standard test). RESULTS: Significant variations (p < 0.05) were found in strength and stiffness between the middle and the proximal or distal aspects of some rods. A significant difference (p < 0.05) was observed when comparing the properties of earlier designs with the properties of more recent designs. Newer rod designs all performed in a similar manner with regard to strength. Strength and rigidity increased with increasing rod diameter in some but not all systems. CONCLUSIONS: Although none of the newer designs appeared to have superior static strength, the individual systems had significant variations in their mechanical properties (bending rigidity), particularly in the proximal and distal sections. It is important that the surgeon become familiar with the individual characteristics of strength and rigidity for the particular devices available and how these might impact fracture healing. Consideration of this information could alter the decision to select one system over another in a complex fracture situation.     

Coil on the loop and selectively enhanced stiffness for improved control: feasibility study in the neonatal ovine model of the large patent ductus arteriosus

RATIONALE AND OBJECTIVES: Several devices have been suggested and tested for interventional closure of the persistent ductus arteriosus. Coils were found effective only in small ducts due to their lack of maneuverability and physical limitation of grip forces leading to risk of embolization. The authors evaluated the feasibility to place single coils with selectively enhanced stiffness into high shunting ductus arteriosus, the coils being deployed and controlled through a veno-arterial loop in a bovine model. METHODS: "Double-cone" shaped, stainless steel coils with enhanced stiffness of the outer rings were mounted on either end on a nitinol core wire. A snap-in mechanism attaches the coil to this delivery wire and is freed by a pusher system of coiled steel wire that is advanced over the core wire. Forming a veno-arterial loop across the patent ductus allows for repositioning into the pulmonary artery or aortic catheter. A chronic lamb model of large patent ductus arteriosus (PDAs) (> or = 9 mm) was used in which ductus patency was secured by a protocol of repetitive angioplasties. Different systems (n = 10) were placed having retrieved the previous coil by a snare after definitive release. RESULTS: Placement of coils was possible in all 10 attempts. The coils were pulled back into the catheters between five and eight times before definitive release. CONCLUSIONS: The device allows controlled placement of single coils in our model of large PDAs and may lead the way to overcome previous limitations of coils. Clinical trials are warranted.     

The feasibility of electronic tracking devices in dementia: a telephone survey and case series

BACKGROUND: Patients with dementia who go out unaccompanied are at risk of accidents or getting lost. It is not known whether they could benefit from electronic tracking devices or whether such devices are practically feasible. METHOD: The likely demand for an electronic tracking device was assessed by means of a telephone survey of a convenience sample of 99 carers. The practical feasibility of a tracking system was assessed in 24 patients with dementia. RESULTS: The telephone survey suggested that 20% of patients were at continuing risk of traffic accidents and 45% were at continuing risk of getting lost. About 7% could have benefited from using the device at the time of survey and a further 11% could have benefited at an earlier point in their illness. In the feasibility study, only nine patients consistently used the device. In two patients, it was successfully used in a search. One patient was injured by a passing vehicle when he had got lost out of range of the device. A major barrier to using the device was recognizing the risk of getting lost before it happened. CONCLUSION: Significant numbers of patients are at risk. Electronic tracking devices may occasionally be useful in carefully selected cases.     

Per-catheter ASD closure

Per-catheter devices for atrial septal defect (ASD) closure have been evolving since 1974. The four major devices available for use on a limited basis in early 1997 are reviewed. These include (in alphabetical order) the Angel Wing device, the ASDOS device, the Buttoned device, and the CardioSeal device (successor to the Clamshell). Sufficient data have been collected to indicate that transcatheter ASD closure is a viable alternative to surgery in selected patients. The advantages of the concept of per-catheter closure over surgical closure should lead to the continued development of devices and techniques for per-catheter treatment of ASD and other septal defects in the years to come.     

A rare complication of implanted central-venous access devices: catheter fracture and embolization

Totally implanted central-venous access devices are frequently used for the administration of chemotherapy or parenteral nutrition. Catheter fracture is a rare complication of these devices, with an estimated rate of 0.1%. We have lately seen three cases of catheter fracture with embolization of a catheter fragment to the heart and pulmonary vessels. These cases are described in this article. Catheter fracture is caused by intermittent compression of the catheter between the clavicula and the first rib, which can occur when the catheter has been inserted too far medially. When, on an X-ray of the chest, the catheter is shown to be compressed at the point where the clavicula crosses the first rib, or when infusion through the device suddenly becomes difficult, the chance of catheter fracture is high and the device should be removed.     

A Novel Semiactive Variable Stiffness Device and Its Application in a New Semiactive Tuned Vibration Absorber

An innovative design for a semiactive variable stiffness (SAVS) device is presented in this paper. This beamlike device is capable of altering its stiffness in a smooth manner between minimum and maximum levels by using the variations of moment of inertia of an area as it rotates around a normal axis passing through its centroid. Analytical expressions for the stiffness of the proposed device have been derived. As an application of the SAVS device in engineering, a semiactive tuned vibration absorber (SATVA) is developed that is capable of real-time retuning and operates effectively in broadband frequency excitations. A single-degree-of-freedom (SDOF) system coupled with the SATVA is considered. The excitation force is assumed to arise from a rotating unbalance whose frequency varies with a constant acceleration and then reaches a steady-state operating condition. The absorber stiffness is varied to tune the absorber’s natural frequency to the forcing frequency in real time. The effectiveness of SATVA is evaluated by comparing the system’s responses with those of the system with passive vibration absorber. The results show the salient features of the proposed SATVA in transient response reduction compared with the traditional passive vibration absorber.     

Aerosol therapy

Aerosol therapy plays a major role in the diagnosis and treatment of various lung diseases. The aim of inhalation therapy is to deposit a reproducible and adequate dose of a specific drug to the airways, in order to achieve a high, local, clinical effect while avoiding serious systemic side effects. To achieve this goal, it is therefore important to have an efficient inhalation device to deliver different medications. However, the currently available therapeutic inhalation devices (nebuliser, pressurised metered-dose inhaler and dry powder inhaler) are not very efficient in aerosol delivery and have several disadvantages. Inhalation devices can be assessed by in vitro studies, filter studies and radiolabelled deposition studies. Several radiolabelled deposition studies have shown that nebulisers and pressurised metered-dose inhalers are not very efficient in aerosol delivery. In children, before 1997, only 0.5% to 15% of the total nebulised or actuated dose from a nebuliser or pressurised metered-dose inhaler actually reached the lungs. These numbers were somewhat improved in adults, 30% of the total nebulised or actuated dose reaching the airways. Aerosol therapy with dry powder inhalers was the most efficient before 1997, 30% of the total dose being deposited in the lungs of adults and children. In 1997, new developments in pressurised metered-dose inhalers much improved their efficiency in aerosol delivery. Lung deposition can be increased by up to 60% with use of a non-electrostatic holding chamber and/or a pressurised metered-dose inhaler with a hydrofluoroalkane propellant possessing superior aerosol characteristics. Several studies comparing the clinical efficiency of different inhalation devices have shown that the choice of an optimal inhalation device is crucial. In addition to the aerosol characteristics, ventilation parameters and airway morphology have an important bearing on deposition patterns. These parameters may be greatly influenced by the patient's acceptance of a specific inhalation device and therefore determine the choice of the device used. It is important for the clinical impact to develop more efficient inhalation devices, which need to be assessed for use in different age groups. These devices should be cheap, easy to use, portable, usable with all medications and environmentally safe.     

Effect of extracorporeal shock wave lithotripsy on implantable cardioverter defibrillator

Extracorporeal shock wave lithotripsy (ESWL) is frequently used for nephrolithiasis of the upper urinary tract. Because of the powerful shock wave and electromechanical forces created, this therapy has been contraindicated in the patient with an implantable cardioverter defibrillator (ICD). To determine whether or not ESWL affects ICD devices, we subjected ten devices to a full course of ESWL. The devices were then returned to the manufacturer to undergo bench analysis, which revealed no abnormalities in function. Additionally, one device was placed in the pathway of the shock wave, resulting in a discharge of the device despite a frequency of ESWL of 100 shocks/min (well below the rate cutoff of that device). Manufacturer analysis of this device, likewise, revealed no abnormalities even though the device had been exposed to the focal point of the shock wave. We conclude that contralateral ESWL is not contraindicated for the patient with an ICD. We do, however, recommend a post-procedure evaluation to ensure appropriate function of the ICD.     

Improving patient care by reporting problems with medical devices

Healthcare practitioners are the primary users of medical devices for direct patient care. As such, they are in the best position to recognize problems that result from the use of medical devices. The outcome of a device-related adverse event or product problem, as with any other medical product, can be serious and result in illness injury, or even death. The sooner that FDA learns about a problem, the sooner the agency can take action to protect patient and user safety. Healthcare practitioners are major contributors to the knowledge base related to device use and safety through astute monitoring, rapid identification of device-related problems, and reporting these problems. An understanding of the voluntary and mandatory mechanism of reporting will ensure that device problems are reported appropriately and in a timely manner. As the primary users of medical equipment for direct patient care, health care professionals have the training and expertise to improve patient care by reporting actual and suspected problems with medical devices.     

Homozygous deletion of the p16INK4A gene occurs more frequently in CD2+ than in CD2+ T-cell acute lymphoblastic leukemia

Right ventricular assist devices are an important part of the armamentarium of cardiac surgeons for the treatment of right-sided circulatory failure after cardiac transplantation or insertion of a left ventricular assist device. However, right ventricular assist device insertion can be technically challenging in the setting of pulmonary hypertension because of a number of concomitant anatomic and physiologic phenomena. We present a technique for the insertion of the right ventricular assist device outflow cannula that is easier and faster to insert, and safer to explant, especially if cardiopulmonary bypass is to be avoided.     

The effect of intermittent pneumatic compression devices on intraoperative blood loss during radical prostatectomy and radical cystectomy

Intermittent pneumatic compression devices are a widely used, effective and presumed risk-free method of deep venous thrombosis prophylaxis, presumably by increasing peak venous blood velocity, and stimulating local and systemic fibrinolysis. We investigated whether intermittent pneumatic compression devices had any effect on intraoperative blood loss or transfusion during radical pelvic urological surgery. To our knowledge no previous study has addressed these issues. Records were reviewed for patients undergoing radical retropubic prostatectomy or radical cystectomy with diversion from 1985 to 1990. A total of 91 cases was reviewed: 38 radical retropubic prostatectomies and 53 radical cystectomies with diversion (34 male and 19 female patients). There were 59 patients with intermittent pneumatic compression devices (29 radical retropubic prostatectomies and 30 radical cystectomies with diversion) and 32 without intermittent pneumatic compression devices (9 radical retropubic prostatectomies and 23 radical cystectomies with diversion). Intraoperative blood loss and transfusions were calculated for each group with and without intermittent pneumatic compression devices. No clinically apparent lower extremity deep venous thrombosis or pulmonary embolus was diagnosed in any patient. For the group with intermittent pneumatic compression devices mean intraoperative blood loss was 2,541 ml. (range 700 to 8,850) versus 1,807 ml. (range 450 to 5,100) without a device, for a statistically significant difference of 734 ml. (p = 0.005). When 5 patients with excessive intraoperative blood loss (more than 5,000 ml.) were excluded the statistically significant difference was maintained. When comparing radical retropubic prostatectomy and radical cystectomy with diversion, with and without intermittent pneumatic compression devices, blood loss was greater for the group with a device for each procedure. Differences in intraoperative blood loss were independent of sex or tumor stage. Intraoperative transfusions were increased by approximately 0.6 units per patient with the device. Our study suggests that intermittent pneumatic compression devices may increase blood loss during a radical pelvic operation.