Medical instrumentation (Med Instrum)

Publisher: Association for the Advancement of Medical Instrumentation

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Other titles Medical instrumentation
ISSN 0090-6689
OCLC 1786771
Material type Periodical
Document type Journal / Magazine / Newspaper

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: The knowledge of liver iron overload is essential for the diagnosis and the therapy of diseases which induce systemic iron overload in the body. The liver needle biopsy is a well-known invasive method to measure liver iron concentration. The Magnetic Iron Detector (MID) susceptometer has proven to be a non-invasive apparatus capable of measuring the iron overload in the whole liver and also managing the follow-up therapy. Methods: The iron overload is obtained by calculating the difference between the magnetization signal of the patient and his/her background signal, which is defined as the magnetization signal that the patient would generate with the basal iron content. The first order approximation of the background signal is calculated from a 3D-laser-scan of the body of the patient. A calibration with healthy volunteers is needed to obtain a model for the calculation of the background signal. Results and Conclusions: From 2005, the MID was used by the Galliera Hospital (Genoa, Italy) and about 2000 evaluations of iron overload were carried out with this instrument. A new generation of MID was developed to substitute the former susceptometer. The project for this new apparatus was started in 2009 and the new version was installed in February 2012 at Galliera Hospital where it is currently in use. The paper describes the new generation of MID and shows how it works focusing on the improvements regarding the engineering of the apparatus, the user interface and the measurement time. Moreover, we herein report the measurement performed on a phantom, the results of the calibration with 69 healthy volunteers and the description of the model by which we calculate the background signal.
    Medical instrumentation 07/2013; 1(5):1-3. DOI:10.7243/2052-6962-1-5
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    ABSTRACT: With the implantation of an automatic device is a need to be confident that the assessment of the output provides a reasonable safety margin for the patient. A single measurement of defibrillation threshold has been used to predict defibrillation efficacy despite known variability of the measure. Relative errors and variability can be reduced if replicate determinations are used. The objective of this experiment was to determine the minimum replicate number to estimate the 'true' mean threshold of defibrillation. Defibrillaton threshold determinations were replicated 7 times in each of 16 anesthetized pigs. Measurements needed for the running mean to reach the 'true' mean within the ranges of ± 0.5 J; ± 1.0 J; ± 1.5 J; 2.0 J and the 95% confidence interval in all animals were 7, 5, 4, 3, and 3. A simple mathematic model was also used to assess this relationship. We conclude that 3 replicate measurements are sufficient to obtain the true mean threshold of defibrillation.
    Medical instrumentation 12/1988; 22(6):298-303.
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    ABSTRACT: This study provides a comparison of self-measurement blood pressure devices, with respect to the standards published by the American National Standards Institute/Association for the Advancement of Medical Instrumentation and statements from the American Heart Association and the National High Blood Pressure Education Program. The results show a wide disparity among the recommendations of select committees, on issues of education and compliance and on design features of this instrumentation. Procedural problems in determining compliance in this study highlight the need for improved objectivity in statements in national standards and for improved awareness of those statements by manufacturers.
    Medical instrumentation 11/1988; 22(5):226-9.
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    ABSTRACT: Advances in technology and treatment have resulted in a growing population of very old and very young people whose lives are technology dependent. These people are being cared for in increasing numbers in their homes by care-givers inadequately trained for the task. The unintended negative consequences and the positive effects of such care are examined, and ethical concerns are raised.
    Medical instrumentation 11/1988; 22(5):222-5.
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    ABSTRACT: A statistical decision-making system, based on daily self measurements obtained at home, has been developed that will predict the clinical status of a patient with cystic fibrosis (CF). The data for the study were collected from patients randomly selected from those served by the University of Minnesota CF Center. Participants recorded four daily measurements (weight, vital capacity, breathing rate, and resting pulse) and one weekly measurement (height) and returned completed diaries to the coordinating center each week. The goal of the rule was to determine whether each patient's clinical status was deteriorating, remaining stable, or improving at the time of the most recent set of weekly measurements. This early detection and intervention criterion (EDIC) is being used in the clinical setting to aid in the management of patients with cystic fibrosis. The computer hardware and software, particularly the relational database, have provided an efficient basis for the continued use of EDIC.
    Medical instrumentation 11/1988; 22(5):240-6.
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    ABSTRACT: The induction of inspiration by delivering a burst of short-duration stimuli to body-surface electrodes is over a century old. The authors have used the term electroventilation to describe the technique. Inspiration can be produced with stimuli applied to electrodes placed bilaterally at the base of the neck, over the phrenic nerve motor points. Transchest electrodes placed anterior to the axillae can be used to stimulate the long thoracic and phrenic nerves. Paraxiphoid electrodes can be used to stimulate the phrenic nerves as they enter the diaphragm. With any of these electrode placements, inspired volumes in excess of spontaneous tidal volumes can be achieved in man, baboon, and dog. Of major importance is the need to use short-duration (less than 10-microseconds) pulses in the train of stimuli that produces contraction of the inspiratory muscles. The duration of inspiration is determined by the duration of the train, which is typically 0.5-1 s. The use of short-duration pulses minimizes the risk of producing cardiac arrhythmias and results in very little sensation at the skin.
    Medical instrumentation 11/1988; 22(5):263-71.
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    ABSTRACT: The acceptance and assimilation of new medical technologies into the health-care arena is a complex process involving financial, humanistic, and clinical considerations. This experimental research compared nurses' attitudes regarding the clinical acceptability of conventional methods of measuring vital signs with their attitudes toward a new, automated method, using the IVAC Model 4000 Vital-Check. Two studies were conducted, at different university-affiliated hospitals, involving different nursing-care-delivery models. The 102 nurses who participated in the studies generally favored the automated method with respect to provider convenience, patient acceptance, and the opportunity to simultaneously perform other nursing assessments. Conventional techniques were preferred for patients on isolation precautions and in some very specific clinical situations such as those requiring detection of abnormalities in the heart rhythm. Interviews of patients were also conducted at both sites and their comments supplemented and supported the quantitative findings for the nurses. Patients seemed to adapt very well to the new technology. They were particularly interested in being better able to monitor their own measurements with the automated process.
    Medical instrumentation 11/1988; 22(5):257-62.
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    ABSTRACT: A three-pronged approach was taken to the development of receptor-based bisensors. First, asymmetric bilayer membranes were developed with one monolayer adaptable to the particular receptor of interest and the other monolayer polymerized to enhance membrane stability. Second, alamethicin and calcium channel complexes were introduced into the stabilized membrane and tested for ion-channel function. Third, a porous support for the receptor-containing membrane was fabricated, which is compatible with silicon technology. Preliminary devices incorporating these components were constructed.
    Medical instrumentation 11/1988; 22(5):247-56.
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    ABSTRACT: This study examined the effects of initial-reading reactivity and measurement methods of blood pressure across different age groups. Subjects were men and women (n = 132), 17 to 96 years of age. Two measurements were obtained from each subject, with a 1-min interval between trials. Each trial consisted of concurrent measurements from each arm, using a standard mercury manometer and an automated blood pressure monitor for use at home. A double-blind control procedure was used. Significant effects were obtained for age (younger, middle, and older age groups), method by trial and age by trial. The blood pressure reactivity and the effect of observer bias varied across age groups. The results support the hypotheses that blood pressure readings decline across trials; that observer bias using traditional methods is sufficient to mask this decline; and that the extent of reactivity and subsequent decline is dependent on age or an age-related increase in blood pressure. Implications of these findings for the use of automated monitoring instruments designed for use at home are discussed.
    Medical instrumentation 11/1988; 22(5):230-3.
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    ABSTRACT: As care for the chronically ill makes increasing demands upon our medical system, cost-effective methods for addressing those demands are being sought. The use of self-monitoring coupled with telecommunication of results to the health-care provider can be expected to provide a partial solution in the appropriate clinical setting. An electronic spirometer with telecommunication ability for use by cystic fibrosis patients in the home has been developed.
    Medical instrumentation 11/1988; 22(5):234-9.
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    ABSTRACT: Hospitals are currently facing cost-cutting pressures. To meet the challenge, some hospitals have downsized by reducing costs and by promoting new lines of business. In this environment, clinical engineers may need a proactive strategy to maintain the integrity of their service, demonstrate its value, and develop new business opportunities including shared-service maintenance, technology assessment, microcomputer applications, and training.
    Medical instrumentation 09/1988; 22(4):201-4.
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    ABSTRACT: A questionnaire was sent to 346 persons certified in clinical engineering (CCEs) worldwide. An impressive 72% return revealed the following: 57% of the CCEs are employed by hospitals, 15% by manufacturers, and 12% by academic institutions; 13% are consultants in private practice. Half of them have been with their current employer for over 9 years; their average age is 44.3 years. Thirty-six percent left hospitals for their present jobs. The median salary of the hospital-based CCEs was in the range of +40,000-45,000/year, whereas that of their non-hospital counterparts was in the range of +50,000-55,000/year. Of the nonhospital CCEs, 25% earned over +70,000/year, while only 3% of the hospital CCEs earned salaries in this category. The mean age of the hospitals CCEs is, however, 4.8 years less than that of the non-hospital CCEs. Although some comments on the profession were particularly critical, the respondents believed strongly that clinical engineering remains a viable career choice and has contributed significantly to health care. Underutilization of clinical engineering talents, particularly in the hospital setting, continues to be the predominate concern and greatest source of job-related frustration.
    Medical instrumentation 09/1988; 22(4):189-200.
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    ABSTRACT: A temperature-based, rate-adaptive, pacing algorithm was developed to benefit the patient. Rate-adaptive pacemakers use a physiologic parameter to identify the need for increased pacing rate. Parameters that have been clinically investigated include venous pH, Q-T interval, respiration, body motion, and blood temperature. The objective of this study was to provide pacing rates resembling normal heart rates in response to various levels and types of activity. A rapid response time (within 30 s of exercise onset) was also sought. Blood temperature, which reflects metabolic activity of all regions, was selected as the physiologic parameter. Right ventricular blood temperature was recorded in 25 patients with implanted Kelvin 500 pacemakers (Cook Pacemaker) during rest and treadmill exercise. The patient population included 16 men and 9 women, age 44-81 years (mean = 72). Indications for pacing were sinus node disease, atrioventricular block, and atrial fibrillation with slow ventricular response. The temperature changed with physical activity and emotional stress. Temperature typically dropped briefly at exercise onset, increased with continued exercise, and returned to the resting level after exercise. These components were employed in developing the temperature-based rate-adaptive algorithm, which was designed to use the rate of temperature change (dT/dt), temperature change (delta T), and baseline temperature (T). The temperature profiles were used to produce simulated pacing rates as determined by the algorithm. The drop in temperature at onset of activity was utilized to provide a rapid increase in pacing rate. As dT/dt became positive and delta T increased, pacing rate was further increased.(ABSTRACT TRUNCATED AT 250 WORDS)
    Medical instrumentation 09/1988; 22(4):182-8.
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    ABSTRACT: The design and construction of a new optical reflectance sensor suitable for noninvasive monitoring of arterial hemoglobin oxygen saturation with a pulse oximeter is described. The reflectance sensor was interfaced to a Datascope ACCUSAT pulse oximeter that was specially adapted for this study to perform as a reflectance oximeter. We evaluated the reflectance sensor in a group of 10 healthy adult volunteers. SpO2 obtained from the forehead with the reflectance pulse oximeter and SpO2 obtained from a finger sensor that was connected to a standard ACCUSAT transmittance pulse oximeter were compared simultaneously to arterial blood samples analyzed by an IL 282 CO-Oximeter. The equation for the best fitted linear regression line between the reflectance SpO2 and HbO2 values obtained from the reference IL 282 CO-Oximeter in the range between 62 and 100% was: SpO2 (%) = 4.78 +/- 0.96 (IL); n = 110. The regression analysis revealed a high degree of correlation (r = 0.98) and a relatively small standard error of the estimate (SEE = 1.82%). The mean and standard deviations for the difference between the reflectance SpO2 and IL 282 measurements was 1.38 and 1.85%, respectively. This study demonstrates the ability to acquire accurate SpO2 from the forehead using a reflectance sensor and a pulse oximeter.
    Medical instrumentation 09/1988; 22(4):167-73.
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    ABSTRACT: A hand-held probe, or one introduced through a catheter, rapidly produces an extremely high, tissue-vaporizing temperature in a precisely defined manner enabling surgeons or interventional radiologists to perform angioplasty, thrombose aneurysms, and vaporize tumors. The probe is operated in a near field of an inductive coil, and the current induced in the biologic tissue is converged maximally at the tip of the probe at the resonance frequency of both the inductor and the probe, producing a maximum temperature in excess of 1400 degrees C. Radio-frequency power controls the probe-tip temperature. The operation of the probe is comparable to that of a CO2 or YAG laser and is complementary to laser-surgical techniques. The low cost relative to lasers and simplicity of the device including its disposable components make the prospect of commercialization of this device promising.
    Medical instrumentation 09/1988; 22(4):205-16.
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    ABSTRACT: Urinary incontinence, the inability to retain urine, creates a misery that cannot be overestimated. The foul odor emanating from the patient repels family and friends to such an extent that it affects the social life of the sufferer. Total incontinence, that is, the continuous loss of urine as opposed to the loss associated with coughing or sneezing, is the most severe type of the malady. For such individuals, the artificial sphincter offers hope for a new life. Incidences of total urinary incontinence as a result of radical prostatectomy in the treatment of carcinoma of the prostate have been reported in the range of 5-50%. Incontinence may occur as a result of injury to the proximal urethra, and it is usually present to some extent in patients with neurogenic bladder dysfunction caused by spinal cord injury, myelomeningocele, or other conditions that affect the micturition centers of the nervous system. Some patients whose urinary tract is completely obstructed and who are therefore unable to urinate, as for example individuals who sustain traumatic complete transection of the urethra with resulting obstructive fibrosis of the urethra, or those patients whose neurogenic spastic sphincter inhibits satisfactory voiding, may benefit from reconstructive surgery or ablation of their pathologic sphincter in order to restore urination. Rehabilitation of such patients can then be complete with implantation of an artificial sphincter to provide urinary control. The alternatives for management include diapers, the placement of external collecting or occlusive devices, or major surgery in which the intestinal tract is used either for conducting the urine to an abdominal collecting bag or as a bladder substitute that is periodically emptied by catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)
    Medical instrumentation 09/1988; 22(4):174-81.
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    ABSTRACT: A scheme to reduce the data corruption caused by tape-speed variation in cassette recorders used for monitoring infant apnea was developed. Low-frequency timing information is recorded on the tape, under the constraints of the frequency response of the recorder, simultaneously with the other signals. This information is extracted during playback and multiplied to a frequency suitable for data sampling, using an electronic, phase-locked loop. Analog-to-digital conversion of the data is performed at a rate proportional to the tape speed, resulting in compensation for speed variation. No direct modification of the speed-control mechanism of the recorder is required. The scheme was evaluated by comparing interval measurements of recorded timing information with and without compensation. Compensation reduced the error of the measurement by nearly an order of magnitude, which was consistent with theoretical predictions. This allows analysis of clinical value to be performed on signals recorded by systems that lack sophisticated speed-control mechanisms.
    Medical instrumentation 07/1988; 22(3):151-4.
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    ABSTRACT: These four examples of technology and its relationship to pre-hospital care will be reviewed: portable defibrillators, pneumatic antishock garment, 911 systems with computer-aided dispatch, and aeromedical transport.
    Medical instrumentation 07/1988; 22(3):143-5.
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    ABSTRACT: Two approaches to intraoperative anesthetic gas monitoring exist today. Central, mass-spectrometer-based systems share cost and analyzer time among several remote locations. Stand-alone monitors are usually infrared analyzers and are dedicated to a single monitoring location. The advantages and disadvantages of each are due primarily to the shared versus dedicated approaches. Dedicated analyzers, while limited somewhat by infrared technology, offer uninterrupted, real-time analysis of anesthetic and respiratory gases. Central systems offer excellent monitoring but are limited to periodic updates of each monitored location. This article attempts a complete analysis of these and other factors affecting the use, reliability, and cost effectiveness of these two approaches to anesthesia gas monitoring.
    Medical instrumentation 07/1988; 22(3):155-60.