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Biomedical subjects

J L Orth

Publications and source records attributed to J L Orth.

6 recordsLinked to original sources
PubMed1988

In vitro development of automatic control for the actively filled electrohydraulic heart.

The in vitro development of automatic control of the actively filled, alternately pumped, volumetrically coupled, electrohydraulic total artificial heart was the goal of this investigation. Control features under study were (a) cardiac output (CO) response to preload; (b) CO relationship to mean aortic pressure (AoP); and (c) control of balanced ventricular outputs. A modified pulmonic valve to increase backflow was used as a balancing mechanism. Hydraulic fluid pressure transducers monitored diastolic pressures, and microprocessor control of motor speed maintained in a mild suction to yield filling rate dependent on atrial pressure. Results indicated a rise in CO from 5 to 9 L/min, with a change in mean right atrial pressure (RAP) from 0 to 7 mm Hg. No significant difference in CO was found as AoP was varied from 80 to 120 mm Hg with a maximum variation of +/- 0.5 L/min on CO and +/- 1 mm Hg on RAP. Balance was maintained for bronchial flows up to 50% with mean left atrial pressure never exceeding 15 mm Hg. An alternately pumped electrohydraulic heart was automatically controlled to respond sensitively to preload changes. Afterload changes did not alter the CO response curve. Automatically controlled, balanced ventricular outputs were maintained.

Algorithms↗
PubMed1985

Speech recognition experience with multichannel cochlear implants.

Four patients received multichannel intracochlear implants before 1978 as part of the University of Utah program. By 1983, sound coding strategies and electronic miniaturization were developed to allow production and use of a portable sound processor/cochlear stimulator unit. Approval for expanded clinical trials has allowed implantation of five additional patients by August 1984. Data on the earlier patients demonstrate stability of electrode thresholds and impedance, low risk of the percutaneous pedestal, and the development of speech recognition scores of greater than 60% with electrical stimulation alone and greater than 90% with electrical stimulation combined with lipreading. Data on recent recipients indicate early electrode threshold stability, lower thresholds for apical electrodes, possibility of replacing single-channel with multi-channel units, and low morbidity of the implantation. Return to function in a verbally communicating environment has been achieved by one earlier patient.

Adult↗
PubMed1983

Intra-aortic balloon pumping in infants and children.

From November 1981 to November 1982, intra-aortic balloon pumping (IABP) was used after surgery in eight patients who were from 6 weeks to 6 years old and who weighed from 4.2 to 16.2 kg. In seven patients, specially constructed intra-aortic balloons with 2.5 and 5.0 ml volumes mounted on No. 5F catheters were used. In the largest and oldest patient, a two-chamber 10 ml balloon was used. The pumping module used was the Datascope System 82. Effective diastolic augmentation of arterial pressure was accomplished in seven of the eight patients and suprasystolic diastolic augmentation was accomplished in four. The two youngest and smallest patients are the only long-term survivors. There were two short-term survivors who died 5 and 10 days after successful IABP. In only one patient was there no appreciable effect of IABP. Miniaturization of the equipment has permitted IABP to be used effectively in pediatric patients.

Assisted Circulation↗
PubMedDate not supplied

Effects of retrovenous myocardial drug delivery after coronary artery occlusion in sheep.

Retrovenous (RV) myocardial delivery of blood and drugs into the coronary sinus (CS) through a 3 lumen balloon catheter was evaluated in sheep (no coronary collaterals) for protection from ventricular fibrillation (VF) during coronary artery occlusion. The balloon was asynchronously inflated (CS occlusion) for 5 sec and then deflated for 5 sec with 1 cc/sec of flow. The left anterior descending coronary artery was occluded with inflation of a percutaneous transluminal coronary angiography balloon and therapy started immediately. In a control group (no therapy, n = 4) all developed VF by 30 min after coronary artery occlusion. The drugs lidocaine (L), esmolol (E), adenosine (A), and deferoxamine (D) were evaluated for effects on eliminating developing VF with intravenous (i.v.) administration compared with RV administration with venous blood (VB) or arterial blood (AB). The percent survival after CA occlusion (no VF) was: L i.v., 0%; L RV with VB, 43%; L RV with AB, 17%; E i.v., 50%; E RV with VB, 70%; A. i.v., 29%; A RV with VB, 88%; D i.v., 17%; and D RV with AB, 80%. There was a trend toward lower myocardial necrosis (seen by tetrazolium stain and/or light microscopy) in the RV survivors (especially with VB) compared with the group i.v. survivors. These data suggest that RV antiarrhythmic drug delivery is a feasible alternative to i.v. administration during CA occlusion.

Adenosine↗