The Square-Wave Electromagnetic Flowmeter: Theory of Operation and Design of Magnetic Probes for Clinical and Experimental Applications

Spencer, Merrill P.; Denison, Adam B.

doi:10.1109/iret-me.1959.5007970

Cited by 57 publications

(18 citation statements)

References 12 publications

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“…A computer system, connected to the flowmeter output, was developed to discount variations due to changes in the concentration of electrolytes in the acidic chyme and the proximity of biliary secretion that can modify the baseline level and thus the integration of the area under the flow curve (Spencer & Denison, 1959). The slow but non-constant shift caused by inherent drift of the electromagnetic probe was also corrected.…”

Section: Validationstudiesmentioning

confidence: 99%

Duodenal bulb control of the flow rate of digesta in the fasted and fed dog.

Malbert

Ruckebusch

1989

The Journal of Physiology

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SUMMARY1. Continuous measurement of the flow of digesta near the pylorus, and 5 cm aborally, was assessed in the conscious dog using a chronically implanted flowmeter. The patterns of flow were related to motor activity of the gastroduodenal junction.2. Electromagnetic measurement of the flow was calibrated in vitro by means of a pulsatile pump. Validation was obtained in vivo by direct evaluation of the amount of chyme collected from an open duodenal cannula and indirectly by a dye-dilution technique.3. After a 12 h fast, only small amounts of gastric contents were delivered into the duodenum. This transfer occurred during periods of irregular motor activity recorded along the gastroduodenal junction, which occupied less than 25% of the recording time. The patterns of flow near the pylorus and beyond the duodenal bulb were correlated to antral and duodenal contractions respectively. 4. After a meal, gastric emptying occurred intermittently and was related to enhanced antral motor activity beyond the duodenal bulb; digesta flowed in clusters of gushes which were related to the duodenal contractions.5. It is concluded that the mechanical role of the duodenal bulb is to change the intermittent juxtapyloric flow of digesta into a uniform flow at the duodenal level.

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Section: Validationstudiesmentioning

confidence: 99%

Duodenal bulb control of the flow rate of digesta in the fasted and fed dog.

Malbert

Ruckebusch

1989

The Journal of Physiology

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“…The "gold standard" for flow-volume measurements is invasive electromagnetic flowmeters. 3 Noninvasive assessment of flow volume is possible by various ultrasound approaches. First is the so-called QFM flowmeter, which integrates Doppler and A-mode information.…”

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confidence: 99%

Reference Values for Vertebral Artery Flow Volume by Duplex Sonography in Young and Elderly Adults

Seidel

Eicke

Tettenborn

et al. 1999

Stroke

121

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Background and Purpose-Vertebrobasilar ischemia has been attributed to a reduction of net vertebral artery flow volume, the product of mean flow velocity and the cross-sectional area of the vessel. It can be determined by duplex sonography. There are no reference values for vertebral artery flow volume in an age group representative of patients with cerebrovascular disease. Methods-We examined 50 nonvascular neurological patients (age 55.8Ϯ14.0 years). Flow velocities and vessel diameters were recorded in the intertransverse (V2) segments bilaterally, and the flow volume was calculated according to the following equations: (1) Q1ϭtime-averaged mean velocityϫarea and (2) Q2ϭ(time-averaged maximum velocity/2)ϫarea. Results-Flow velocities and vessel diameters tended to be lower on the right side, resulting in a lower flow volume. Flow volumes (according to Equation 1) were 77.2Ϯ29.8 mL/min on the right side, 105.3Ϯ46.4 mL/min on the left side, and 182.0Ϯ56.0 mL/min net. Side-to-side differences were not significant. Flow volumes calculated with the 2 equations did not differ significantly. An age dependence could not be shown, but vessel diameters and net vertebral artery flow volumes were significantly lower in women than in men. The normal range for net vertebral artery flow volume defined by the 5th to 95th percentiles is between 102.4 and 301.0 mL/min. This wide range is due to the high interindividual variability of the parameters. Conclusions-On

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“…The manufacturer states that the response of this instrument is flat to 50 cps. Calibrations were carried out following each experiment according to the method outlined by Spencer and Denison (7). Flow pulses were generated by passing 30-ml volumes of the experimental animal's own blood through the flow transducer and recording the flow signal at maximum paper speed on the Dynograph (250 mm/sec).…”

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Influence of Sympathetic Nerve Stimulation on Right Ventricular Outflow-Tract Pressures in Anesthetized Dogs

Pace

Keefe

Armour

et al. 1969

Circulation Research

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Stellate ganglion stimulation in the anesthetized, open-chest dog consistently resulted in the generation of pressure differences which averaged 20 mm Hg across the infundibular region of the right ventricle. Before stimulation, peak systolic pressures in the sinus and conus were closely matched. Peak sinus pressure showed ah average increase of 184 and 162% during stimulation of the left and right stellate ganglia, respectively. Simultaneously, peak conus pressure showed average increases of 88 and 61% during left and right stellate ganglion stimulation, respectively. In addition, the maximal rate of intrasinus pressure development (dP/dt) was usually elevated above conus dP/dt, and this change contributed to the generation of early systolic pressure differences. Cervical vagosympathetic nerve stimulation following atropine administration also resulted in the generation of infundibular pressure differences, but the latter were less marked than those elicited during stellate ganglion stimulation. Elevations in main pulmonary arterial resistance abolished the induced pressure differences by allowing peak conus pressure to rise to the same extent as peak intrasinus pressure. Simultaneous electromagnetic flow recordings of pulmonary arterial blood flow during stellate ganglion stimulation revealed two-to five-fold increases in maximum flow acceleration with relatively little change in stroke volume. Infundibular pressure gradients which developed in early systole were associated with maximum flow changes in the pulmonary artery.ADDITIONAL KEY WORDS stellate ganglion stimulation pulmonary arterial occlusion pulmonary arterial blood flow sinus and conus regions of the right ventricle vagosympathetic stimulation right ventricular infundibulum • The early anatomical and embryological studies of Sir Arthur Keith (1, 2) demonstrated that the conus arteriosus of the developing embryo was incorporated into the right ventricular myocardium and formed the terminal portion of the infundibulum in the adult heart. The conus homologue on the left side was obliterated during the embryological development of the left ventricle. In lower forms, From the Department of Physiology, Loyola University, Stritch School of Medicine and the Graduate School, 1400 South First Avenue, Hines, Illinois 60141.This work was supported in part by U. S. Public Health Service Grants HE 08682 and CM 999 from the National Institutes of Health.Received October 14, 1968. Accepted for publication, January 24, 1969. such as the tortoise, the conus arteriosus is anatomically distinct from the rest of the right ventricular musculature, and Woodbury and Robertson (3) demonstrated that this region can act as a functional stricture to divert blood through the interventricular foramen to the left ventricle. Studies on the canine heart by March et al. (4) have shown that the inflow or sinus region of the right ventricle is activated before the infundibular region, thus demonstrating physiological inflow-outflow pressure differences. Recently Tobin et al...

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The Square-Wave Electromagnetic Flowmeter: Theory of Operation and Design of Magnetic Probes for Clinical and Experimental Applications

Cited by 57 publications

References 12 publications

Duodenal bulb control of the flow rate of digesta in the fasted and fed dog.

Duodenal bulb control of the flow rate of digesta in the fasted and fed dog.

Reference Values for Vertebral Artery Flow Volume by Duplex Sonography in Young and Elderly Adults

Influence of Sympathetic Nerve Stimulation on Right Ventricular Outflow-Tract Pressures in Anesthetized Dogs

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