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The Blood Pressure Measuring System is described. It measures blood pressure by the noninvasive Korotkoff sound technique on a continual basis as physical stress is imposed during experiment M092, Lower Body Negative Pressure, and experiment M171, Metabolic Activity.
The accuracy and range of studies on cardiovascular and pulmonary functions can be greatly facilitated if the motions of the underlying organ systems throughout individual cycles can be directly visualized and readily measured with minimum or preferably no effect on these motions. Achievement of this objective requires development of techniques for quantitative noninvasive or minimally invasive dynamic and stop-action imaging of the organ systems. A review of advances in dynamic quantitative imaging of moving organs reveals that the revolutionary value of cross-sectional and three-dimensional images produced by various types of radiant energy such as X-rays and gamma rays, positrons, electrons, protons, light, and ultrasound for clinical diagnostic and biomedical research applications is just beginning to be realized. The fabrication of a clinically useful cross-section reconstruction device with sensing capabilities for both anatomical structural composition and chemical composition may be possible and awaits future development.
In both physiologic and clinical studies, standing is often loosely equated with head-up tilt (HUT) although the cardiovascular effects of these variants of orthostasis have not been formally compared, except for heart rate. The effects of HUT and standing were measured noninvasively in male volunteers satisfying identical criteria for age and normal status. In both postures, there were significant increases in heart rate, pre-ejection period, isovolumic contraction time, and the ratio of pre-ejection to ejection period, and significant decreases in ejection period and ejection time index. All of these changes were greater for standing than for tilt. Pulse transmission time changed significantly (-14%) only with tilt. We conclude that head-up tilt and standing are rather comparable but not physiologically identical forms of orthostasis.
The time course of the recovery period was characterized by noninvasive measurements after 4 minute bicycle exercise at 3 separate work loads in volunteers with normal peak responses. Most responses started immediately to return toward resting control values. Left ventricular ejection time and stroke volume change are discussed. Changes in pre-ejection period were determined by changes in isovolume contraction time, and factors affecting the degree and rate of return are considered. The rates of change in the ejection time index and in the ratio pre-ejection period/left ventricular ejection time were virtually independent of load throughout most of recovery.
The use of thallium imaging as a noninvasive method to accurately screen shuttle passengers for latent coronary artery disease was investigated. All radionuclide procedures were performed using an Anger type camera with a high resolution collimator. A minimum of 200,000 counts were collected for each image using a 20% window centered on the 69-83 keV X-rays. For the images obtained following injection with the patient at rest, the testing was begun 10 minutes after injection. Injections of TT during exercise were made at a point near the termination of the treadmill procedure as determined by either the appearance of ST segment changes on the electrocardiogram consistant with subendocardial ischemia, the appearance of angina-like chest pain in the patient or fatigue in the patient which required cessation of the test. The severity of heart disease was based on the medical history, physical exam, exercise electrocardiograms, chest X-rays and the coronary arteriogram.
The general objective of the research was to provide the space and life sciences directorate with an improved biostereometric measurement capability. This objective was determined from the usefulness of stereophotogrametric techniques developed during the Apollo and Skylab Missions to measure body conformation, surface area, volume and relative density of astronauts. These noninvasive anthropometric measurements provided invaluable data concerning the physiological, biochemical and nutritional effects of the space environment upon the human body. The indirect nature of the technique has many advantages over other methods, and has a potential for many other applications. The stereophotographs contain an enormous amount of data which can be later reexamined should the need arise.
The paper presents a microflora analysis of a 5-year-old male child with severe combined immune deficiency who was delivered by Caesarean section and continuously maintained in an isolator. Despite precautions, it was found that the child had come in contact with at least 54 different microbial contaminants. While his skin autoflora was similar to that of a reference group of healthy male adults in numbers of different species and the number of viable cells present per square centimeter of surface area, the subject's autoflora differed from the reference group in that significantly fewer anaerobic species were recovered from the patient's mouth and feces. It is suggested that the child's remaining disease free shows that the reported bacteria are noninvasive or that the unaffected components of the child's immune defense mechanisms are important.
Existing radiographic imaging systems provide images which represent an integration or averaging over the energy spectrum. In order to provide noninvasive angiography it is necessary to image the relatively small amounts of iodine which are available following an intravenous administration. This is accomplished by making use of the special spectral characteristics of iodine. Two methods will be presented. One involves a special grating for encoding the iodine information in the form of a fine line pattern. This is subsequently decoded to provide images of iodinated structures which are otherwise almost invisible. The second method utilizes a scanned X-ray beam which is rapidly switched in the high energy region. In this region, iodine experiences significant variations in the attenuation coefficient while bone and soft tissue do not. An efficient and accurate X-ray detector can be used with scanned X-ray beams. This provides a high degree of sensitivity enabling the visualization of small vessels containing relatively dilute iodine.
Signal is the term used to denote the characteristic in the time or frequency domain of the probing energy of the system. Processing of this signal in diagnostic ultrasound occurs as the signal travels through the ultrasonic and electrical sections of the apparatus. The paper discusses current signal processing methods, postreception processing, display devices, real-time imaging, and quantitative measurements in noninvasive cardiology. The possibility of using deconvolution in a single transducer system is examined, and some future developments using digital techniques are outlined.
The instruments and techniques of biomagnetic measurement have progressed greatly in the past 15 years and are now of a quality appropriate to clinical applications. The paper reports on recent developments in the design and application of SQUID (Superconducting Quantum Interference Device) magnetometers to biomagnetic measurement. The discussion covers biomagnetic field levels, magnetocardiography, magnetic susceptibility plethysmography, ambient noise and sensor types, principles of operation of a SQUID magnetometer, and laboratory techniques. Of the many promising applications of noninvasive biomagnetic measurement, magnetocardiography is the most advanced and the most likely to find clinical application in the near future.
Experimental results are presented which tend to validate a previously developed theory of sound production in the human lung over a particular Reynolds number range. In addition, a new, presently nonunderstood, phenomenon was observed at higher Reynolds number. These results, which show how sound generation in the lung depends upon the physiologically important variables of volume flow rate and bronchial diameter, have potentially important application in noninvasive lung examination and the diagnosis of lung disease.
Vibration analyis is nondestructive and noninvasive. Transistor isolated from heat (or cold) of surroundings by filament suspension. Filaments made of polyester are (0.005 in) 0.127 mm in diameter. Transistor lead wires are wrapped around certain filaments. Applicable for testing filament mounts too delicate for testing by tension probes.
Current pulses lower resistance of silver-filled epoxies. Capacitive discharge reduces interfacial resistance between aluminum surfaces joined with silver-filled epoxy. Technique offers noninvasive solution to problem of attaching grounding brackets to aluminum honeycomb structures.
Computer-enhanced visualization of coronary arteries and lesions within them is discussed, comparing invasive and noninvasive methods. Trial design factors in computer lesions assessment are briefly discussed, and the use of the computer edge-tracking technique in that assessment is described. The results of a small pilot study conducted on serial cineangiograms of men with premature atherosclerosis are presented. A canine study to determine the feasibility of quantifying atherosclerosis from intravenous carotid angiograms is discussed. Comparative error for arterial and venous injection in the canines is determined, and the mode of processing the films to achieve better visualization is described. The application of the computer edge-tracking technique to an ultrasound image of the human carotid artery is also shown and briefly discussed.
A new noninvasive immobilization procedure to be used on rats has been developed to study immobilization-induced muscle hypersensitivity to normal glucocorticoid concentration, subsequent muscle atrophy, and atrophy recovery. The immobilization procedure involves encasing the hind limb in a light-weight plasticlike cast (10 percent the usual plaster weight), completely resistant to animal gnawing. The effects of right-angle immobilization of the ankle on the slow fiber soleus, and the fast fiber extensor digitorum longus, resemble the effects of weightlessness. The increased concentration of glucocorticoid receptor sites in immobilized and denervated muscle is discussed, along with the chronic loss of muscle mass that occurs in practically all dystrophies. It is concluded that lack of mechanical work in a zero gravity environment is a major cause of glucocorticoid hypersensitivity in the body's musculature.
Screening test developed for detecting a range of vision defects in eye, including common precursors to amblyopia. Test noninvasive, safe, and administered easily in field by operator with no medical training. Only minimal momentary cooperation of subject required: Thus, test shows promise for use with very young children. Test produces color-slide images of retinas of eyes under specially-controlled lighting conditions. Trained observer screens five children per minute.
Blink rate is reported to vary dependent upon ongoing task performance, perceptual, attentional and cognitive factors, and fatigue. Five levels of task difficulty were operationally defined and task performance as lines read aloud per minute were measured. A single noninvasive infrared TV eyetracker was modified to measure blinking and an on-line computer program identified and counted blinks while the subject performed the tasks. Blink rate decreased by 50% when either task performance increased (fast reading) or visual difficulty increased (blurred text); blink rate increased greatly during rest breaks. There was no change in blink rate during one hour experiments even though subjects complained of severe fatigue.
A noninvasive accurate method for measuring the temperature of tissue beneath the surface of a living body is described. Ultrasonic signals are directed into beads of a material that are inserted into the tissue with a syringe. The reflected signals indicate the acoustic impedance or resonance frequency of the beads which in turn indicates the temperature of the tissue. A range of temperatures around the melting temperature of the material can be measured by this method.