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At least 253 records · Page 14Linked to original sources
PubMed1965

INVESTIGATION OF AN OPERATOR METHOD IN THE ANALYSIS OF BIOLOGICAL TRACER DATA.

Some factors affecting the usefulness of a linear operator in the analysis of tracer data were evaluated. Application of the operator to a sum of two exponential components resulted in the separation of the rate constants with an accuracy of 10 to 15 per cent if they differed by a factor of at least 2 and the error in the data was about 2 per cent. A factor of 4 was necessary if the error in the data was 6 per cent, and of 6 if the error was 10 per cent. The ratio of amplitudes varied from near unity to equality with the ratio of rate constants. However, if the ratio of amplitudes was greater than the ratio of rate constants the method would not resolve the rate constants. Application of the operator to a sum of three exponential components was also considered.

Computers↗
PubMedDate not supplied

Analysis of the density of pleural fluid analogs by computed tomography.

A noninvasive method for differentiating transudative and exudative pleural effusions could make thoracentesis unnecessary in many cases. Since computed tomography (CT) can be used to measure tissue densities, it has a potential use in assessing density of intrathoracic fluid. This study was performed to test this possibility. Plastic syringes containing water, saline, and three saline-albumin solutions with densities up to 1.021 g/cc were scanned individually in air, in a chest phantom, and in a dog thorax during apnea. We found significant positive correlations between specific gravity and CT density; coefficients ranged from 0.85 to 0.99. Regression lines for the different test conditions were not statistically different. However, CT number variability, as indicated by the average standard deviation (SD), did differ for the test conditions: 1) Syringes alone, average SD was 3.8 HU; 2) chest phantom, average SD was 5.5 HU adjacent to rib and 5.8 HU anterior to vertebral column; 3) dog chest average SD was 19.2 HU with heart motion and 9.4 HU without heart motion. These results suggest that heart motion is a major factor in CT number variability in vivo, and that differentiation of transudates from exudates is not possible with current CT methods.

Animals↗
PubMed1976

An inexpensive blood pressure-heart rate computer for laboratory or teaching use.

A special-purpose analog computer circuit is described that, given a signal proportional to arterial blood pressure, generates signals equal to systolic, diastolic, pulse, and mean pressure at a calibration of 100 mmHg/V. Heart period and rate are also derived at calibration of 1 s/V and 100 bpm/V, respectively. The outputs are step-function beat-by-beat changes in these six variables suitable either for analog recording, or presentation to a panel meter for digital display.

Blood Pressure Determination↗
PubMed1982

Computer analysis of mechanical activity of gastroduodenal junction in unanaesthetized dogs.

In four conscious dogs mechanical activity of the gastroduodenal junction was recorded with chronically implanted strain gauge transducers and induction coils. The data were evaluated by a computer. Analog circuits were used in order to reduce the data which were transferred to the computer. In the digestive state the contractions of the pyloric sphincter and duodenal bulb were correlated in such a way that the contractions of the duodenal bulb were inhibited when the gastric waves travelled across the antrum and that the bulb contracted once or twice when the peristaltic waves arrived at the gastroduodenal junction. However, the timing between pyloric and duodenal contractions was imperfect. Contraction maxima of the duodenal bulb often occurred before the pylorus was closed. This was due to the different inherent frequencies of the pyloric and duodenal contractions. In the interdigestive state the timing between the pyloric and duodenal contractions was as imperfect as during the digestive state. In phase III of the interdigestive activity, however, the strong antral contractions were regularly associated with inhibition of the duodenal bulb. This phenomenon can be interpreted as co-ordination between gastric and duodenal activity.

Animals↗
PubMed1977

Computer-calculated kanamycin dosage regimen and monitoring.

The applicability of a computerized dosage regimen determination based on a recently developed method for drugs following the minimum inhibitory concentration pattern (bacteriostatic drugs) has been tested for kanamycin injected intramuscularly in 8 patients with varying degrees of renal impairment. The dosage regimens for maintaining a minimum therapeutic kanamycin concentration of 5.0 micron g/ml was determined with the Wang 700 C Computer. After the 1st, 2nd, 3rd, 6th, 9th, and 12th dosing interval blood samples were taken and the acual kanamycin serum concentrations determined. The expected multiple dose serum level curves for each patient were simulated using the Comdyna Dose Generator Analog Computer and the individual actual serum concentrations were monitored. The actually found serum level data were compared to the expected values based on the dosage regimen equations and to the steady state equations. Additionally, the expected peak maxima were calculated. The proposed method resulted in effective and safe kanamycin serum levels.

Adult↗
PubMed1976

A computer module for the continuous monitoring of cardiac output in the operating theatre and the ICU.

A new pulse contour method to determine stroke volume and cardiac output continuously in patients on a beat-to-beat basis from the aortic pressure wave has been implemented in the form of a simple, inexpensive, fully automatic computing module for a commercially available patients monitoring system (Philips Medical Systems). Its reliability has been tested and shown in a computer analog, in experimental studies in 10 dogs (not reported here), in 22 hemodynamic studies on 20 young healthy volunteers and during 41 days in 20 postsurgical patients in the ICU, the most important result being that erros figures (15 and 19% respectively in the two human studies) are of the same order as when two standard methods, Fick and dye dilution are compared. The clinical studies have further indicated the easy applicability of the module 1 degree in the monitoring of critically ill patients in ICU's, 2 degrees as a monitor of the systemic circulation during anesthesia, and 3 degrees as a tool for studying the hemodynamic effects of pharmacological agents. The instrument consitutes no burden to the patients and has, several times during the course of the evaluation, provided an early warning of a deteriorating hemodynamic status of the patient to the physician.

Age Factors↗