Biomedical subjects

F Kepics

Publications and source records attributed to F Kepics.

3 recordsLinked to original sources

PubMed1997

Programmed stimulation for simulation of atrial tachyarrythmias.

Swine have become the preeminent non-human animal model for testing of cardiac assistance devices. Such devices must be robust to perturbations in the EKG; therefore it is expeditious, as part of cardiac assistance device testing, to simulate arrhythmias such as atrial flutter and fibrillation in swine. Methods for producing atrial tachyarrythmias include surgical ablation or crushing of atrial tissue and the administration of drugs. These are dangerous, unreliable and usually irreversible; in varying combinations and degrees. When we applied rapid evenly spaced electrical atrial pacing in swine, the variability of ventricular response was less than expected from the corresponding arrhythmia in man. We will describe efforts to produce reversible atrial tachyarrythmias in swine, using programmed stimulation, with the desired degree of ventricular response variability.

Animals↗

PubMed1987

Reflectance photoplethysmography as an adjunct to assessment of gravitational acceleration tolerance: preliminary findings.

We have examined the feasibility of using reflectance photoplethysmography to assess Gz acceleration tolerance. Reflectance plethysmograms recorded using a sensor placed on the region of the superficial temporal artery were analysed along with the mean value and the pulsatile component of the Doppler velocity recorded from the opposite temporal artery. The photoplethysmogram signal and pulsatile and mean Doppler velocities were examined as predictors of impending peripheral light loss (PLL) during the experiments. Photoplethysmography correctly predicted a large percentage of the PLL runs (80.5%) and non-PLL runs (98.3%). Mean Doppler velocity predicted a higher percentage of PLL runs (88.1%), but with an unacceptably low rate of non-PLL runs (77.2%). The pulsatile Doppler velocity yielded only 50.7% correct prediction of PLL runs. The results of this preliminary study indicate that, with an improved design of the sensor and the electronics, it may be possible to use reflectance photoplethysmography in acceleration tolerance experiments as a reliable predictor of impending peripheral light loss.

Acceleration↗

PubMed1987

An experimental microcomputer controlled system for synchronized pulsating anti-gravity suit.

An experimental system to deliver synchronized external pressure pulsations to the lower body is described in this technical note. The system is designed using a microcomputer with a real time interface and an electro-pneumatic subsystem capable of delivering pressure pulses to a modified anti-G suit at a fast rate. It is versatile, containing many options for synchronizing, phasing and sequencing of the pressure pulsations and controlling the pressure level in the suit bladders. Details of its software and hardware are described along with the results of initial testing in a Dynamic Flight Simulator on human volunteers.

Computers↗