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Articles 5791 - 5820 of 6326

Full-Text Articles in Engineering

Influence Of Interposed Ventilation Pressure Upon Artificial Cardiac Output During Cardiopulmonary Resuscitation In Dogs, Charles F. Babbs, W D. Voorhees, K R. Fitzgerald, H R. Holmes, L A. Geddes Jan 1980

Influence Of Interposed Ventilation Pressure Upon Artificial Cardiac Output During Cardiopulmonary Resuscitation In Dogs, Charles F. Babbs, W D. Voorhees, K R. Fitzgerald, H R. Holmes, L A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

This study was conducted to determine the effects of high pressure interposed ventilations during cardiopulmonary resuscitation (CPR). Cardiac output was measured by a modified indicator dilution technique in eight anesthetized, intubated mongrel dogs. Positive pressure ventilations (12/min, 80% O2) were interposed after every five chest compressions (performed at 62/min) by a mechanical chest compressor (Thumper®). On repeated trials in the same animal, ventilation pressures from 10-50 cm of H2O were tested in randomized sequence, while the technique of chest compression was held constant. Arterial blood gases immediately after resuscitation were monitored. Increasing ventilation pressure had surprisingly little effect on cardiac …


Evaluation Of The Operating Internal Resistance And Capacitance Of Intact Trapezoidal Waveform Defibrillators, Charles F. Babbs, Sj Whistler, La Geddes Jan 1980

Evaluation Of The Operating Internal Resistance And Capacitance Of Intact Trapezoidal Waveform Defibrillators, Charles F. Babbs, Sj Whistler, La Geddes

Weldon School of Biomedical Engineering Faculty Publications

No abstract provided.


Regional Blood Flow During Cardiopulmonary Resuscitation In Dogs, W D. Voorhees, Charles F. Babbs, W A. Tacker Jan 1980

Regional Blood Flow During Cardiopulmonary Resuscitation In Dogs, W D. Voorhees, Charles F. Babbs, W A. Tacker

Weldon School of Biomedical Engineering Faculty Publications

To determine differences in regional blood flow during cardiopulmonary resuscitation (CPR) versus normal cardiac function, we measured regional blood flow to sev~ral organs in 19 pentobarbital-anesthetized dogs (6-12 kg). Regional blood flow was measured during sinus rhythm in 5 dogs and during electrically induced ventricular fibrillation with CPR in the other 14 dogs. Regional blood flow and cardiac output were measured using radioactively labelled polystyrene microspheres of 15 ±3P diameter, injected into the left ventricle. Adequacy of microsphere mixing at low cardiac outputs was verified by comparing flow rates to paired organs. Cardiac output was 175 ml/kg/min during sinus rhythm …


Therapeutic Indices For Transchest Defibrillator Shocks: Effective, Damaging, And Lethal Electrical Doses, Charles F. Babbs, Willis A. Tacker, John F. Vanvleet, Joe D. Bourland, Leslie A. Geddes Jan 1980

Therapeutic Indices For Transchest Defibrillator Shocks: Effective, Damaging, And Lethal Electrical Doses, Charles F. Babbs, Willis A. Tacker, John F. Vanvleet, Joe D. Bourland, Leslie A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

Although prospective studies of defibrillator shock overdose cannot be performed in man, the therapeutic indices of various defibrillating current waveforms can be measured in animals. We determined the ratios TD50/ED50 and LD50/ ED50 (where TD50 = median "toxic" or damageinducing dose, ED50 = median effective or defibrillating dose, and LD50 = median lethal dose) as measures of the therapeutic index for damped sine wave defibrillator shocks in dogs. Death of an animal and/or any degree of cardiac damage found by gross or microscopic examination were defined as harmful effects of shock, analogous to drug toxicity. In terms of peak current, …


An Animal Model For Testing Automatic Defibrillators, J D. Bourland, Charles F. Babbs, W A. Tacker, L A. Geddes Jan 1980

An Animal Model For Testing Automatic Defibrillators, J D. Bourland, Charles F. Babbs, W A. Tacker, L A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

A promising therapy for ventricular fibrillation--a life-threatening cardiac arrhythmia--is the implantation of an automatic defibrillator. A critical component of such a device is the system that detects the presence of ventricular fibrillation. Automatic systems for detecting ventricular fibrillation have been tested with arrhythmias produced by electric shocks in normal canine hearts, but have not been tested with spontaneous arrhythmias in hyperirritable hearts. We have developed an animal model to create arrhythmias without electrical stimulation and have used it to test our automatic defibrillator. This model permits evaluation of both reliability to diagnose ventricular fibrillation and reliability to reject other tachyarrhythmias.


A New Technique For Repeated Measurement Of Cardiac Output During Cardiopulmonary Resuscitation, L A. Geddes, Charles F. Babbs Jan 1980

A New Technique For Repeated Measurement Of Cardiac Output During Cardiopulmonary Resuscitation, L A. Geddes, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

We have developed a method for measurement of cardiac output during CPR with ventricular fibrillation. The method avoids the problems encountered when conventional techniques are used under the conditions of very low cardiac output. The method consists of injecting 5% saline as the indicator into the left ventricle and detecting its appearance in the descending aorta by withdrawing blood through an electrically calibrated conductivity cell. The adequacy of indicator mixing has been verified by obtaining dilutions curves simultaneously from the brachial and femoral arteries. Cardiac output can be determined even when output is as low as 7 ml/min/kg during CPR …


Influence Of Adrenergic Drugs Upon Vital Organ Perfusion During Cpr, H R. Holmes, Charles F. Babbs, W D. Voorhees, W A. Tacker, B De Garavilla Jan 1980

Influence Of Adrenergic Drugs Upon Vital Organ Perfusion During Cpr, H R. Holmes, Charles F. Babbs, W D. Voorhees, W A. Tacker, B De Garavilla

Weldon School of Biomedical Engineering Faculty Publications

To determine whether adrenergic drugs administered during cardiopulmonary resuscitation (CPR) alter the distribution of artificial card:l.ac output, we measu"red regional blood flow and cardiac output using radioactive microspheres in 12 dogs. Ventricular fibrillation was induced electrically and CPR was immediately begun with a mechanical chest compressor and ventilator (Thurn per ( R) ) at 60 compressions/min, with a ventilation:compression ratio of 1:5, a compression duration of 0.5 sec, and a ventilation pressure of 20 em H 2 o. Compression force was sufficient to develop 40-50 mmHg peak intraesophageal pressure. After 30 sec of CPR, either 0.9% saline vehicle or 50 …


Dependence Of Defibrillation Threshold Upon Extracellular/Intracellular K+ Concentrations, Charles F. Babbs, S J. Whistler, G Yim, L A. Geddes Jan 1980

Dependence Of Defibrillation Threshold Upon Extracellular/Intracellular K+ Concentrations, Charles F. Babbs, S J. Whistler, G Yim, L A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

The effect of increasing extracellular potassium concentration (Ko) upon electrical ventricular defibrillation threshold was investigated in pentobarbital anesthetized dogs treated with intravenous potassium chloride. Defibrillation threshold fell during potassium intoxication. The percent decrease in defibrillation threshold was linearly related to the logarithm of Ko and to the potassium equilibrium potential, EK, calculated from measured extracellular and intracellular potassium concentrations of ventricular muscle. In dogs supported by left ventricular bypass in order to maintain the circulation during potassium intoxication, the values of Ko and EK required for spontaneous, K+ induced defibrillation (electrical defibrillation …


Dynamic Intraesophageal Imagining Of The Heart With Ultrasound, N E. Fearnot, Charles F. Babbs, J D. Bourland, L A. Geddes Jan 1980

Dynamic Intraesophageal Imagining Of The Heart With Ultrasound, N E. Fearnot, Charles F. Babbs, J D. Bourland, L A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

Real-time images of the heart from within the esophagus are produced by a new intraesophageal ultrasonic sector scanner. Sixty images per second are displayed on a gray scale CRT in real-time and recorded on standard videotape for review. By interactive positioning of the esophageal probe, heart ventricles, atria, and valves can be visualized and their dynamics can be studied. The esophageal probe comprises four 5 MHz PZT-5 piezoelements of 6.35 mm diameter, mounted on a shaft that rotates at 900 rpm. The piezoelements are pulsed at a 5 kHz rate and the echoes are processed electronically.


New Versus Old Theories Of Blood Flow During Cpr, Charles F. Babbs Jan 1980

New Versus Old Theories Of Blood Flow During Cpr, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Today, the physiology of blood flow during external chest compression appears more complicated than had previously been imagined. New evidence requires that at least two possible mechanisms be considered for generating artificial circulation by external chest compression. The first is the classical mechanism in which the heart propels blood because it is squeezed between the sternum and the spine. The second is a more recently appreciated mechanism in which the entire thorax acts as a pump because of global intrathoracic pressure changes. The first might be called the cardiac pump mechanism and the second might be called the thoracic pump …


The Effects Of Added Softening Agents Upon The Behavior Of Cold Recycled Asphalt Mixtures : Interim Report, Akio Iida Jan 1980

The Effects Of Added Softening Agents Upon The Behavior Of Cold Recycled Asphalt Mixtures : Interim Report, Akio Iida

JTRP Technical Reports

No abstract provided.


The Fabric Of A Medium Plastic Clay Compacted In The Laboratory And In The Field : Interim Report, Dean Matthews White Jan 1980

The Fabric Of A Medium Plastic Clay Compacted In The Laboratory And In The Field : Interim Report, Dean Matthews White

JTRP Technical Reports

No abstract provided.


Additives To Control Slaking In Compacted Shales : Interim Report, Mariappa Surendra Jan 1980

Additives To Control Slaking In Compacted Shales : Interim Report, Mariappa Surendra

JTRP Technical Reports

No abstract provided.


The Effect Of Laboratory Compaction On The Compressibility Of Compacted Highly Plastic Clay : Interim Report, Albert Dibernardo, C. W. Lovell Jan 1979

The Effect Of Laboratory Compaction On The Compressibility Of Compacted Highly Plastic Clay : Interim Report, Albert Dibernardo, C. W. Lovell

JTRP Technical Reports

No abstract provided.


Characterization Of Cold Mixed Asphalt Emulsion Treated Bases, Michael S. Mamlouk Jan 1979

Characterization Of Cold Mixed Asphalt Emulsion Treated Bases, Michael S. Mamlouk

JTRP Technical Reports

No abstract provided.


The Effect Of Laboratory Compaction On The Unconsolidated Undrained Strength Behavior Of A Highly Plastic Clay : Interim Report, David W. Weitzel, C. W. Lovell Jan 1979

The Effect Of Laboratory Compaction On The Unconsolidated Undrained Strength Behavior Of A Highly Plastic Clay : Interim Report, David W. Weitzel, C. W. Lovell

JTRP Technical Reports

No abstract provided.


Analysis Of Hardened Concrete For Admixture Content : Interim Report, Larry Chester Muszynski Jan 1979

Analysis Of Hardened Concrete For Admixture Content : Interim Report, Larry Chester Muszynski

JTRP Technical Reports

No abstract provided.


Development And Use Of A Computer Simulation Model For The Evaluation Of Design And Control Alternatives For Intersections Of Minor Road With Multi-Lane Rural Highways: Selection Of Simulation Model: Interim Report, Ahmed Essam Radwan, Kumares C. Sinha, Harold L. Michael Jan 1979

Development And Use Of A Computer Simulation Model For The Evaluation Of Design And Control Alternatives For Intersections Of Minor Road With Multi-Lane Rural Highways: Selection Of Simulation Model: Interim Report, Ahmed Essam Radwan, Kumares C. Sinha, Harold L. Michael

JTRP Technical Reports

No abstract provided.


Evaluation And Development Of Synthetic Trip Distribution Modeling Techniques As Applied To Small Urban Areas : Interim Report, James Robert Mekemson, Kumares C. Sinha Jan 1979

Evaluation And Development Of Synthetic Trip Distribution Modeling Techniques As Applied To Small Urban Areas : Interim Report, James Robert Mekemson, Kumares C. Sinha

JTRP Technical Reports

No abstract provided.


Methodology For Evaluating The Impacts Of Energy, National Economy, And Public Policies On State Highway Financing And Performance, Fred L. Mannering Jan 1979

Methodology For Evaluating The Impacts Of Energy, National Economy, And Public Policies On State Highway Financing And Performance, Fred L. Mannering

JTRP Technical Reports

No abstract provided.


The Effects Of Simplifying Traffic-Zone And Street-Network Systems On The Accuracy Of Traffic Assignments In Small Urban Areas In Indiana : Interim Report, Edward Wilson Hanscom, Kumares C. Sinha Jan 1979

The Effects Of Simplifying Traffic-Zone And Street-Network Systems On The Accuracy Of Traffic Assignments In Small Urban Areas In Indiana : Interim Report, Edward Wilson Hanscom, Kumares C. Sinha

JTRP Technical Reports

No abstract provided.


Superior Bluegrasses For Roadside Turf, William Hugh Daniel, R. P. Freeborg Jan 1979

Superior Bluegrasses For Roadside Turf, William Hugh Daniel, R. P. Freeborg

JTRP Technical Reports

No abstract provided.


Traffic Speed Report No. 107 : Interim Report, James Robert Mekemson, George K. Stafford Jan 1979

Traffic Speed Report No. 107 : Interim Report, James Robert Mekemson, George K. Stafford

JTRP Technical Reports

No abstract provided.


Development And Use Of A Computer Simulation Model For The Evaluation Of Design And Control Alternatives For Intersections Of Minor Road With Multi-Lane Rural Highways: Model Application: Interim Report, Ahmed Essam Radwan, Kumares C. Sinha, Harold L. Michael Jan 1979

Development And Use Of A Computer Simulation Model For The Evaluation Of Design And Control Alternatives For Intersections Of Minor Road With Multi-Lane Rural Highways: Model Application: Interim Report, Ahmed Essam Radwan, Kumares C. Sinha, Harold L. Michael

JTRP Technical Reports

No abstract provided.


Relationship Of Highway Development And City Development For Non-Metropolitan Places In Indiana, Hadi Yamin Jan 1979

Relationship Of Highway Development And City Development For Non-Metropolitan Places In Indiana, Hadi Yamin

JTRP Technical Reports

No abstract provided.


Validation And Practical Application Of The Utcs-1s Network Simulation Model On An Urban Arterial Street : Interim Report, Bruce Allen Hillson Jan 1979

Validation And Practical Application Of The Utcs-1s Network Simulation Model On An Urban Arterial Street : Interim Report, Bruce Allen Hillson

JTRP Technical Reports

No abstract provided.


Traffic Speed Report No. 109 : Interim Report, Richard Philip Guenthner, George K. Stafford Jan 1979

Traffic Speed Report No. 109 : Interim Report, Richard Philip Guenthner, George K. Stafford

JTRP Technical Reports

No abstract provided.


The Development And Application Of A Standard Compaction-Degradation Test For Shales : Interim Report, Barney Conrad Hale Jan 1979

The Development And Application Of A Standard Compaction-Degradation Test For Shales : Interim Report, Barney Conrad Hale

JTRP Technical Reports

No abstract provided.


Development And Use Of A Computer Simulation Model For The Evaluation Of Design And Control Alternatives For Intersections Of Minor Road With Multi-Lane Rural Highways: Field Studies And Model Validation: Interim Report, Ahmed Essam Radwan, Kumares C. Sinha, Harold L. Michael Jan 1979

Development And Use Of A Computer Simulation Model For The Evaluation Of Design And Control Alternatives For Intersections Of Minor Road With Multi-Lane Rural Highways: Field Studies And Model Validation: Interim Report, Ahmed Essam Radwan, Kumares C. Sinha, Harold L. Michael

JTRP Technical Reports

No abstract provided.


Attenuation And Speed Of 10 Mhz Ultrasound In Canine Blood Of Various Packed Cell Volumes At 37c, D J. Hughes, L A. Geddes, Charles F. Babbs, J D. Bourland, V L. Newhouse Jan 1979

Attenuation And Speed Of 10 Mhz Ultrasound In Canine Blood Of Various Packed Cell Volumes At 37c, D J. Hughes, L A. Geddes, Charles F. Babbs, J D. Bourland, V L. Newhouse

Weldon School of Biomedical Engineering Faculty Publications

The attenuation coefficient and the speed of 10 MHz ultrasound were determined in canine blood at 37 oC by a differential path length technique. Blood specimens with packed cell volumes (PCV) ranging from 0 to 53% were prepared by separating the cells from the plasma and mixing the two components. The mean attenuation coefficient increased linearly with packed cell volume, the least squares regression function being  (dB/cm) = 0.992 +0.039 PCV with a standard error of the estimate = 0.255. The speed of 10 MHz ultrasound, c, in millimetres per second, increased with packed cell volume, the regression function …