The need to develop clinical methods for the noninvasive monitoring of regional blood perfusion, i.e., the blood flow through the very fine capillaries in body tissue, has long been felt. Hitherto existing methods exhibit limitations, such as insufficient measurement depth and poor time- or space-resolution, which restrict the measurements that can be performed. Dymling (1982) introduced a new CW Doppler ultrasound method for noninvasive blood perfusion measurement which might be one possible solution to this problem. Preliminary experiments indicated a correlation between blood flow and measured perfusion value. Unexpectedly large variations in the recorded perfusion values lead to further investigation of the method, both in vitro using a specially designed flow phantom and in vivo. This study indicates that at least some of the large variations recorded are the result of measurement errors caused by movement artifacts or ultrasonic signal interferences. Methods to diminish the effects of these artifacts are discussed.

Artifacts↗

PubMed1991

Calculation of pulse-wave velocity using cross correlation--effects of reflexes in the arterial tree.

The need to investigate the elastic properties of arterial vessels in situ for the early recognition of degenerative disorders in arteries has long been apparent. Pulse-wave diagnostics has been used in traditional medicine, but only in a qualitative way. By measuring the vessel diameter change, simultaneously at two levels along an artery, it should be possible to calculate the pulse-wave velocity (PWV). A newly developed ultrasonic instrument, DIAMOVE, was designed to provide a two-dimensional, real time, B-mode image for display of the exact position of two measurement sites; a computer-controlled digital phased-locked loop detector for the measurement of diameter changes; and a personal computer for the display of the momentary displacement of the artery walls. The cross-correlation technique was used on the information from the vessel wall movements to calculate the resulting PWV. Early measurements on healthy patients showed some unexpected artifacts, which were found to be due to reflected waves, affecting the shape of the pulse-wave at the sites of measurement. A modified PWV estimation algorithm, where only the foot of the pulse-wave in every beat is utilized, seems to have solved this problem and now makes the method suitable for clinical use.

Algorithms↗

PubMed1991

Aortic diameter pulse waves and blood flow velocity in the small, for gestational age, fetus.

An ultrasound phase-locked, echo-tracking system was used for noninvasive measurements of pulsatile diameter changes in the descending aorta of 60 small, for gestational age (SGA), fetuses and of 60 fetuses appropriate for gestational age (AGA). Pulsed Doppler ultrasound was used for the recording of blood flow velocity in the aorta and in the umbilical artery of the SGA fetuses. In the SGA fetuses, a weight-related higher end-diastolic diameter and a lower relative pulse amplitude suggest that diastolic blood pressure was increased; a less steep rise of the initial ascending part of the pulse wave and a lower relative pulse amplitude suggest that the absolute stroke volume was decreased. Except for a positive correlation between relative pulse amplitude and mean velocity in the aorta, no correlation was found between diameter pulse waves and blood flow velocity. Aortic diameter pulse waves apparently yield no unequivocal information as to peripheral resistance, for which purpose blood flow velocity waveform analysis would seem, at least at present, to be the only available method.

Adult↗

PubMed1991

A new ultrasonic method for fluid property measurements.

A new ultrasonic method for fluid property measurements is described. The method uses ultrasound to generate acoustic streaming in a fluid. The resulting flow velocity will vary due to several viscous parameters of the fluid. If there are acoustic scatterers in the fluid, it will be possible to monitor the resulting flow velocity with an ultrasound Doppler device. The same acoustic energy is then utilized both to generate the acoustic streaming in the medium and to measure the resulting flow. The method seems to be very well suited for monitoring biological processes. Of special interest, for measurements on contaminated blood or on fluids in a fermentation process, is the method's ability to investigate liquids in a completely closed vessel.

Animals↗

PubMed1991

Measurements of ultrasonic fields with optical diffraction tomography.

This article describes a light diffraction technique that allows a measurement of ultrasonic pressure and phase in the cross-section of an ultrasonic beam. The light diffraction measurements are based on the Raman-Nath model of ultrasonic continuous-wave light diffraction. The diffracted light intensity can be expressed as an integration of sound pressure along the light path. This integration is analogous to the integration of the absorption coefficient in x-ray tomography. Tomography algorithms can be employed on the light measurement data to calculate the pressure and phase in a measuring plane perpendicular to the ultrasound propagation vector. The reconstruction of the measurement plane is done with an implementation of an algebraic reconstruction technique (ART). Satisfactory results are obtained with 10 projections. The measurement method is applicable up to Raman-Nath parameter values of 2.3. The experimental results are compared to miniature PVDF hydrophone measurements.

Algorithms↗

PubMed1991

Two-dimensional airborne ultrasound real-time linear array scanner--applied to screening for scoliosis.

Diagnostic ultrasound is an established, noninvasive and harmless method for imaging the shape and appearance of organs and other tissues inside the body, and it has been used in many clinical applications for more than three decades. We have now applied some of this well-known technique together with the use of airborne ultrasound in medical applications, to build an equipment for anthropometrical investigation outside the body, e.g., measuring and registration of the shape and form of the human back. This is mostly done for screening purposes of young people in an attempt to find patients developing scoliosis, and in order to circumvent some of the disadvantages with the traditional screening method in this field of medical application.

Back↗

PubMed1991

Inflammatory cell response in bronchoalveolar lavage fluid after nitrogen dioxide exposure of healthy subjects: a dose-response study.

The combination of environmental chamber exposure and bronchoalveolar lavage (BAL) was used to study the effects of the common air pollutant nitrogen dioxide (NO2). Eighteen healthy nonsmokers were exposed to NO2 during 20 min in an exposure chamber during light bicycle ergometer work. All subjects were examined with BAL at least 3 wks before exposure, as a reference. The subjects were re-examined with BAL, in groups of eight, 24 h after exposure to 4, 7 and 10 mg NO2.m.3 (2.25, 4.0 and 5.5 ppm), respectively. An inflammatory cell response was found after exposure to all concentrations. An increase in the number of lymphocytes in BAL fluid was observed after 7 and 10 mg.m.3 (p less than 0.05 and 0.02, respectively). An increase in the number of mast cells, that appears to be dose-dependent, was found after exposure to all concentrations. The proportion of lysozyme positive alveolar macrophages was elevated after exposure to 7 mg.m.3. The inflammatory mediators fibronectin, hyaluronan, angiotensin converting enzyme (ACE) and beta 2-microglobulin were unchanged by exposure. Due to the findings of inflammatory cell changes far below the peak exposure limits for work places in industrialized countries, 9-18 mg.m.3, the safety of these limits is questioned. Studies are in progress in our laboratory using BAL to evaluate the effects of repeated NO2 exposure.

Adult↗

PubMed1990

[Hellmuth Hertz deceased--one of the creators of echocardiography].

Explore the source record for details and available documents.

Echocardiography↗

PubMed1990

Stability of Markers Used for Identification of Two Rhizobium galegae Inoculant Strains after Five Years in the Field.

The stability of identification markers was examined for two Rhizobium galegae inoculant strains after 5 years in the field. The two strains are genetically closely related, but differ in their lipopolysaccharides. Strain HAMBI 540 has lipopolysaccharide of the rough type, whereas that of strain HAMBI 1461 is of the smooth type. The properties that were examined for 10 field isolates of each inoculant type were symbiotic phenotype, phage type, intrinsic antibiotic resistance, maximum growth temperature, lipopolysaccharide and total soluble protein patterns, immunological properties, DNA restriction profiles, and DNA hybridization patterns, which were determined by using nifHDK and recA sequences as probes. Of these properties, all remained stable in soil, with the exception of some variation in intrinsic antibiotic resistance and the acquisition of an extra EcoRI restriction fragment by one of the isolates. Thus, both the rough and the smooth lipopolysaccharide phenotypes persisted equally well in soil.

Journal Article↗

PubMed1989

[Ovarian cancer--a new method of paracentesis].

Explore the source record for details and available documents.

Ascitic Fluid↗

PubMed1989

Quantification of fetal motor activity in early pregnancy.

Real-time ultrasonography in obstetrics has proved that active movements are already present in the first trimester of pregnancy. A new semi-automatic ultrasound method was developed for objective quantitative recording of fetal movements in early pregnancy using a real-time multi-linear array scanner and a Time-Distance recorder. The equipment registers changes in the distance between a fixed marker and the fetal structures displayed on the screen of the ultrasound scanner. The output signals are recorded on a polygraph. Fetal movements were recorded continuously for 30 min in 62 normal 10-, 11- and 12-week-old fetuses. The median number of movements did not differ significantly in the three groups, being 150, 159 and 154, respectively. The median time incidence of movements was 17, 18 and 17%, respectively. The method is now being applied in studies evaluating various drug effects on fetal motor behaviour in early pregnancy.

Female↗

PubMed1989

Patient-handling skill, back injuries, and back pain. An intervention study in nursing.

The aim of this intervention was to evaluate the effect of training on patient-handling skills and prospectively to assess the effect of skill on subsequent back pain and back injuries in nursing. Of a total of 255 nurses, 199 were assessed for their skill in patient-handling. One-half (control group) received traditional training in patient-handling, and the other half (trained group) received a curriculum of instruction totaling 40 hours. The skills of both groups were assessed on graduation. The control group was rated as less competent in patient-handling. Nurses in both groups were questioned about the prevalence of back pain and incidence of back injuries in the first year after graduation. In multiple regression analysis, the major risk indicators for back injuries were poor patient-handling skill, low numbers of repetitions in the sit-up test, and high work-load scores. High score on the hysteria scale of Middlesex Hospital Questionnaire was a risk indicator for all kinds of back pain. Though back pain was independent of patient-handling skill, those rated as "bad" or "poor" had more back injuries (24%) than those who had been rated as "good" or "excellent" (2%) (P less than 0.001), but the difference between the trained and control groups was not statistically significant. It was concluded that back injuries may be prevented by the teaching of patient-handling skills.

Back Injuries↗

PubMed1989

Restriction fragment length polymorphism analysis of Rhizobium galegae strains.

Total DNA of various Rhizobium galegae strains representing different geographical origins, and taxonomic divergence was digested with three restriction enzymes separately, Southern blotted, and hybridized with six heterologous probes. The sequence divergences for different pairwise comparisons were calculated from proportions of conserved hybridizing fragments. The unweighted pair group method was used to group the strains. The symbiotic common nod and nifHDK probes used were highly conserved and grouped the strains according to the host plant, Galega orientalis or G. officinalis. The grouping derived from combined data of the constitutive hemA, glnA, ntrC, and recA probes was similar to that obtained in total DNA-DNA hybridization experiments. The constitutive probes grouped the strains in a different order than did the symbiotic probes, a result that may reflect interstrain transfer of symbiotic sequences in the course of evolution.

Blotting, Southern↗

PubMed1989

Cell response in bronchoalveolar lavage fluid after sulfur dioxide exposure.

Environmental chamber exposure and bronchoalveolar lavage (BAL) were used to study the dose-response relationship between short-term exposure to sulfur dioxide (SO2) and inflammatory reactions in the human lung as reflected in BAL fluid. Healthy subjects were exposed to 10, 13, 20, or 30 mg/m3 for 20 min. BAL was performed several weeks preexposure and 24 h postexposure. Mast cells, lymphocytes, lysozyme positive macrophages, and the total number of macrophages were significantly increased after SO2 exposure. A dose-dependent increase in the cell response in BAL fluid was observed after exposure to 10-20 mg/m3, but no further increase was detected after 30 mg/m3. Inflammatory cell response was found in BAL fluid at SO2 levels that occur in industrial indoor environments worldwide, and cell response to SO2 was also seen below the short-term exposure limit of Sweden and many other countries (13 mg/m3).

Adult↗