PubMed Health⌕ Search

Biomedical subjects

J E Snyder

Publications and source records attributed to J E Snyder.

7 recordsLinked to original sources
PubMed1990

Effects of position changes on transcutaneous carbon dioxide tension in neonates with respiratory distress.

Routine neonatal care includes frequent position changes. Recent research has concluded that positions other than supine may result in beneficial physiologic responses. Specifically, several studies suggest that neonates may ventilate more effectively in a prone rather than in a supine position. This study tested the hypothesis that transcutaneous carbon dioxide tension (TcPCO2) would be lower in the prone than in the supine position in neonates with respiratory distress. Fourteen ventilated infants were studied. TcPCO2 was measured and recorded in prone, supine, and right-side-lying positions for each subject. There were no statistically significant differences in mean TcPCO2 values between the three positions (F = .45; df 2,39; P = .64). The relationship between TcPCO2 and PaCO2 values was stable (r = .88) during the studies. The results indicate that changing a neonate's position does not significantly alter transcutaneous carbon dioxide tension.

Blood Gas Monitoring, Transcutaneous↗
PubMed1987

Continuous-wave Doppler for the noninvasive evaluation of aortic blood velocity and rate of change of velocity: evaluation in dogs.

A new continuous-wave Doppler device is described, which has the capability of measuring peak aortic blood velocity and acceleration noninvasively in the ascending aorta of patients. To test the accuracy of the device, blood velocity and acceleration in the ascending aorta were compared with measurements obtained using an electromagnetic flowmeter in 16 open-chest anesthetized dogs. The Doppler probe was hand held directly on the aorta. Aortic flow was measured with a cuff electromagnetic flow transducer placed at the root of the aorta. Isoproterenol and propranolol, sometimes in combination with lidocaine, were administered intravenously to augment or reduce left ventricular contractile performance. Values of peak velocity, measured with the Doppler, corresponded closely to values measured with the electromagnetic flowmeter (r = 0.95). Values of peak acceleration also corresponded closely with the electromagnetic flow measurements (r = 0.96). The results indicate that valid measurements of blood acceleration in the ascending aorta, as well as blood velocity, can be obtained with continuous-wave Doppler.

Animals↗
PubMed1986

Real-time orthogonal mode scanning of the heart. I. System design.

A necessary percursor to real-time three-dimensional echocardiographic imaging is the ability to obtain multiple planes of acoustic data simultaneously. A new ultrasound imaging technique facilitates the display of two real-time orthogonal B-mode images (O-mode). The O-mode technique uses a novel two-dimensional transducer and system processor to interrogate the two perpendicular planes simultaneously, yielding sector arcs that share one origin. It permits simultaneous display of two sector arcs on a single monitor either side by side or in a two-dimensional projection designed to convey the three-dimensional nature of the acoustic data. Clinical results from the first 50 patients undergoing O-mode evaluation indicate that image quality in the two simultaneously obtained planes is equal to that of a single plane when the system is operating in its conventional format. These data confirm the feasibility of real-time multiplane imaging. The system design offers the potential for the future addition of more simultaneous planes and, thus, the possibility of real-time three-dimensional ultrasound imaging.

Adult↗
PubMed1986

Noninvasive evaluation of left ventricular performance based on peak aortic blood acceleration measured with a continuous-wave Doppler velocity meter.

Peak aortic blood acceleration is recognized to be a sensitive index of global left ventricular performance. In the present study peak acceleration was assessed noninvasively in patients with a continuous-wave Doppler velocity meter. Peak aortic blood velocity and peak blood acceleration were measured by placing the ultrasonic transducer at the suprasternal notch. Measurements were obtained in 36 patients undergoing diagnostic cardiac catheterization. Peak velocity and acceleration were measured at rest just before left ventriculography. In patients with ejection fractions greater than 60%, peak acceleration was 19 +/- 5 m/sec/sec. In patients with ejection fractions of 41% to 60%, peak acceleration was lower, at 12 +/- 2 m/sec/sec (p less than .001). In patients with ejection fractions of 40% or less, peak acceleration (8 +/- 2 m/sec/sec) was markedly lower than in patients with ejection fractions greater than 60% (p less than .001). Peak acceleration showed a good linear correlation with ejection fraction (r = .90), and a better power fit (r = .93). These results indicate that peak acceleration, measured noninvasively with a continuous-wave Doppler velocity meter, is a useful indicator of global left ventricular performance.

Aorta↗
PubMed1979

[Electroophthalmological characteristics in ischemic retinopathy (author's transl)].

In the ERG the b-wave and the oscillatory potentials are reduced or nonrecordable in ischemic retinopathy. The photopic b-wave appeared to be more sensitive than the scotopic b-wave. In the EOG the slow oscillation is reduced. These clinical observations are in accordance with the results of experimental studies in rhesus monkeys.

Animals↗
PubMed1970

Infection control.

Explore the source record for details and available documents.

Cross Infection↗