Medical instrumentation最新文献

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.

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.

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)

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)

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.

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.

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.

Airway management in resuscitation of the traumatized patient is a complex and challenging area for the health care provider and the medical engineer involved in the improvement of airway management instrumentation. Surgical and nonsurgical airway management is discussed, with emphasis placed on the instrumentation available and its appropriate uses and limitations. Suggestions for areas requiring new innovations are included.

Monitoring the critically injured patient is imperative, to assure adequate resuscitation from shock. Unfortunately, the commonly monitored variables correlate poorly with ultimate survival. As a result, therapy is inappropriately focused. Invasive monitoring (by way of a pulmonary artery catheter and arterial cannula) permit serial determinations of parameters pertaining to oxygen delivery as well as oxygen consumption. These are crucial in defining the shock state as well as the need for therapeutic intervention. Recent advances in mixed venous oximetry offer alternative means of assessing the adequacy of peripheral delivery of oxygen. With the advent of metabolic carts, it became feasible to measure respiratory gas exchange to determine oxygen consumption. Complexity, expense, and time clearly limit practical application of that technology to a small percentage of patients in the intensive care unit. Unfortunately, unrecognized hypoxemia remains a common problem. Advances in noninvasive monitoring offer alternative means to assess oxygenation. Pulse oximetry and transcutaneous oxygen monitoring are the state of the art. The pertinent devices are easy to use, portable, and accurate. Knowledge of their technical and physiologic limitations is needed to assure reliability. Their potential role extends beyond the intensive care unit setting, such as with prolonged radiologic evaluation or difficult transportation.

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.