Biomedical Engineering and Bioengineering Commons^™

Physical Principles Of Local Heat Therapy For Cancer, Charles F. Babbs, David P. Dewitt

Weldon School of Biomedical Engineering Faculty Publications

Local hyperthermia therapy for cancer can produce selective heating of solid tumors on the basis of known physical laws. If energy is deposited in the general region of the tumor, temperature tends to develop in the tumor higher than that in surrounding normal tissues. The goal of therapy is to achieve cytotoxic temperature elevations in the tumor for an adequate period of time, without damaging nearby normal tissues. Several modalities exist for local heat treatment, of which radiofrequency and ultrasound offer the most promise for controlled, localized heating at depth. A paucity of blood flow in the tumor compared to …

Alteration Of Defibrillation Threshold By Antiarrhythmic Drugs: A Theoretical Framework, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

No abstract provided.

Cardiac Output During Cpr: A Comparison Of Two Methods, D L. Silver, R J. Murphy, Charles F. Babbs, L A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

Simultaneous Fick and saline dilution methods were compared for measuring cardiac output during experimental cardiac arrest and resuscitation in anesthetized dogs. During cardiopulmonary resuscitation (CPR) cardiac output averaged 53 ± 30 ml/min-kg (42% of pre-arrest values). Values obtained using the Fick vs. saline methods were highly correlated (r = 0.96), and were not statistically different (t = 1.47, df = 16).

Transchest Defibrillation Under Conditions Of Hypothermia, W A. Tacker, Charles F. Babbs, D R. Abendschein, L A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

This study was conducted to determine whether or not hypothermia changes ventricular defibrillation threshold. Ventricular fibrillation was induced by electrical stimulation of the endocardium in pentobarbital anesthetized dogs, both during normothermia and hypothermia produced by circulating 8 °C water through a rubber bladder implanted in the peritoneal cavity. Defibrillation threshold was determined as the shock strength needed to defibrillate the ventricles and differing no more than 10 percent from a shock strength that failed to defibrillate. Defibrillation threshold current was stable for body temperatures ranging from 37 oC to 22 oC. Threshold energy increased linearly with decreasing temperature in keeping …

Effect Of Thoracic Venting On Arterial Pressure, And Flow During External Cardiopulmonary Resuscitation In Animals, Charles F. Babbs, Nicholas Bircher, Dennis E. Burkett, Henry A. Frissora, Brian C. Hodgkin, Peter Safar

Weldon School of Biomedical Engineering Faculty Publications

To test the hypothesis that fluctuations in global intrathoracic pressure are the dominant cause of blood flow during external cardiopulmonary resuscitation (CPR) the authors studied the effects of open pneumothorax on experimental CPR in 7 domestic pigs and 12 mongrel dogs. Similar studies were conducted independently at three laboratories and are reported jointly. All studies were conducted during electrically induced ventricular fibrillation and with standard CPR technique, including ventral-dorsal chest compression at 60/min, 0.5 sec compression duration, 1:5ventilation:compression ratio. During alternate periods of CPR, intrathoracic pressure was vented through bilateral chest tubes, placed to create open pneumothorax and partial collapse …

Cardiac Output During Cardiopulmonary Resuscitation At Various Compression Rates And Durations, Kevin R. Fitzgerald, Charles F. Babbs, Henry A. Frissora, Robert W. Davis, Douglas I. Silver

Weldon School of Biomedical Engineering Faculty Publications

Cardiac output during cardiopulmonary resuscitation (CPR) was measured by a modified indicator-dilution technique in 20 anesthetized dogs (6-12 kg) during repeated 1- to 2-min episodes of electrically induced ventricular fibrillation and CPR, produced by a mechanical chest compressor and ventilator. With compression rates from 20 to 140/min and compression durations (duty cycles) from 10 to 90% of cycle time, cardiac output (CO) was predicted by the equation:

,

where CR is compression rate, DC is duty cycle, SV_max (19 ml) is the effective capacity of the pumping chamber, and k_l (0.00207 min) and k₂ (0.00707 min) are …

Metric Units Of Measure- Part I Length, Area And Volume, Elbert C. Dickey, Allen R. Rider, Gerald R. Bodman

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The metric system was developed by government and scientific groups in 1790 to replace a host of diverse measuring systems used throughout France. By the early 1900's it had been adopted by most European and Latin American nations. By 1970 over 90 percent of the world, including all major industrial nations except the United States, had either adopted the metric system or had undertaken programs to implement it.

Use of the decimal-based metric system was made legal in the United States by Congress in 1866. Although some scientists and educators readily adopted the metric system, little acceptance was made by …

Metric Units Of Measure - Part Ii Fluid Volume, Mass, Temperature, Pressure, Power And Energy, Elbert C. Dickey, Allen R. Rider, Gerald Bodman

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The metric and U.S. customary systems of measure differ in terminology for fluid volume, mass, temperature, pressure, power and energy. The relationships between the metric and U.S. customary system for these units are described and illustrated graphically in the following text.

Fluid Volume- Fluid volumes are usually measured in milliliters or liters. Small quantities of liquid products are expressed as milliliters or as cubic centimeters. Gasoline, milk and other similar sized volumes are measured in liters.

Mass - Mass is the amount of matter in an object and is normally referred to as weight. The common metric units of …

Lecture Draft On Sensory Recall Device - 1980, Wendy J. Gordon

Scholarship Chronologically

Perception is a bodily function. The brain “sees” according to the orders which the optic nerve relays from its position at the back of the eye. Similarly, it is the brain which also "hears." As we know from our dreaming and our remembering, neither eye nor ear is indispensable to having the sensations of seeing and hearing.

Design Of Vegetative Filters For Feedlot Runoff Treatment In Humid Areas, D. H. Vanderholm, Elbert C. Dickey

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The vegetative filter approach uses overland flow or shallow channelized flow to treat feedlot runoff by infiltration, dilution and filtration. Based on extensive monitoring of four field systems in Illinois over a two year period, acceptable performance standards were selected. Design criteria to meet the standards were developed for both the overland flow vegetative filters and the channelized or serpentine terrace filters. A major design criterion for both types of vegetative filters is the time required for applied runoff to flow the length of the filter.

An alternative to using zero-discharge treatment systems to control feedlot runoff is to replace …

Home Sewage Treatment Systems, Elbert C. Dickey, Robert P. Pharris, Phillip W. Harlan, Gary Hosek

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Homeowners in areas not served by municipal sewage treatment systems face a problem of providing safe and effective wastewater treatment systems for their homes.

There are several methods currently available for proper treatment of home sewage, including septic tank absorption fields, mounds, lagoons, aerobic treatment units and others. These systems and their advantages and disadvantages are discussed in this NebGuide.

Treatment and disposal of domestic sewage is of concern because of the variety of pathogenic organisms contained in sewage. These include bacteria, viruses, and other microorganisms that come from the digestive tract, respiratory tract, and skin of man. Some of …

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

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

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

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

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

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

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

Weldon School of Biomedical Engineering Faculty Publications

The effect of increasing extracellular potassium concentration (K_o) 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 K_o and to the potassium equilibrium potential, E_K, 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 K_o and E_K 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

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

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 …

Center Pivot Irrigation In Nebraska: An Institutional Analysis Case Study, Thomas Nutt-Powell, Stewart Landers

Department of Agricultural and Biological Systems Engineering: Faculty Publications

This paper is one of a series resulting from institutional analysis of photovoltaic (PV) acceptance. It reports the results of a study of institutional factors influencing acceptance of center-pivot irrigation in the Nebraska agricultural community. Center-point irrigation (CP) was an interesting topic for study because (1) it was a major recently introduced technological innovation in agriculture which (2) had potentially detrimental attributes – water and energy intensity. A brief historical review of the introduction and acceptance of center-pivot irrigation in the Nebraska agricultural community is presented. Institutions which were a likely part of this institutional arena relative to CP introduction …

A Pressure Injection Device For Inoculation Of Maize With Bacterial Phytopathogens, Randall R. Carlson, A. K. Vidaver, David S. Wysong, J. H. Riesselman

Biological Process Development Facility: Staff Publications

A pressure injection device (PID) was used to inoculate maize (Zea mays) with bacterial phytopathogens. The PID was evaluated for its speed, effectiveness, and precision relative to the needle-eye method of inoculation. Corynebacterium nebraskense, Erwinia stewartii, and Pseudomonas andropogonis were each used successfully as inocula to infect maize and produce symptoms typical of Goss's wilt, Stewart's wilt and bacterial stripe, respectively. Quantitative inoculation with the PID was faster and as statistically precise as using a calibrated needle-eye.

A Septic Tank System For Sewage Treatment, Elbert C. Dickey, Phillip W. Harlan, Gary Hosek

Department of Agricultural and Biological Systems Engineering: Faculty Publications

A properly designed, installed ao1d maintained septic tank system is an approved method of sewage treatment for private residences in rural or urban areas where public sewage treatment systems are not available. The components of a septic system are the house sewer, the septic tank and the absorption field, as illustrated in Figure 1. Sewage flows to the septic tank through the house sewer. In the septic tank, the solids are separated from the liquids, undergo anaerobic digestion and are stored as sludge at the bottom of the tank. The liquid (septic tank effluent) flows to the absorption field …

A Comparative Analysis Of Intrusion Of Incisor Teeth Achieved In Adults And Children According To Facial Type, Ronald L. Otto

Loma Linda University Electronic Theses, Dissertations & Projects

A comparison of incisor intrusion achieved in deep bite adults and children was made. Facial type was also examined for affect upon intrusion achieved. Fifty-five cases treated with Bioprogressive mechanics were studied cephalometrically, including twenty-four adults and thirty-one children. Neither age nor facial type was found to be statistically related to the amount of incisor intrusion achieved in this sample. A method of measuring intrusion at the root apices was devised which was felt to give a more accurate indication of actual bodily intrusion. More external root changes during treatment were observed for adults than for growing children. Wide latitude …

Maintaining A Septic Tank System, Elbert C. Dickey, Gary Hosek, Phillip W. Harlan

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Once a septic tank and absorption field are installed, you can do several things to prolong their life, thus protecting an investment which may cost $2500 or more. Here are several tips you can follow.

Often overlooked or neglected is the fact that septic tanks should be inspected at least once annually. In every properly functioning septic tank, sludge accumulates in the bottom. This sludge is composed of solid materials and must be removed periodically. If the sludge is not removed, the accumulated solids will build up in the septic tank and will begin to wash out into the absorption …

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 …

Elevation Of Ventricular Defibrillation Threshold In Dogs By Antiarrhythmic Drugs, Charles F. Babbs, Gkw Yim, S J. Whistler, W A. Tacker, L A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

Effects of antiarrhythmic drugs upon the threshold delivered energy (TDE) and threshold peak current (TPC) for electrical ventricular defibrillation by damped sinusoidal shocks were investigated in 25 pentobarbital-anesthetized dogs. TDE and TPC were increased by the three antiarrhythmic drugs tested. Bolus injections produced a transient rise, and continuous infusions produced a steady rise in defibrillation threshold. The maximal percent elevations in mean defibrillation threshold during the 60 minutes after intravenous drug treatment in groups of n = 5 dogs were: Treatment % increase in TDE % increase in TPC Lidocaine bolus (3 mg/kg) 48 26 Lidocaine (0.5 mg/Kg/min) 99 45 …

Measurements Of Young's Modulus Of Elasticity Of The Canine Aorta With Ultrasound, D J. Hughes, Charles F. Babbs, L A. Geddes, J D. Bourland

Weldon School of Biomedical Engineering Faculty Publications

We have developed an ultrasonic technique for determining the dynamic Young's modulus of elasticity (E) of the canine aorta in vivo. Young's modulus was measured in the descending thoracic aorta (DTA) and the abdominal aorta (AA) of 12 dogs over a range of mean blood pressures from 40-200 mmHg. The vessels were excised and dynamic moduli were determined in vitro postmortem from pressure-volume curves. The data so obtained were compared to the in vivo values. In vivo and in vitro moduli increased exponentially with mean distending pressure (P). The equation of best fit for these data was of the form …

Micro-Relief Surface Depression Storage: Changes During Rainfall Events And Their Application To Rainfall-Runoff Models, J. Kent Mitchell, Benjamin A. Jones Jr.

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Micro-relief surface depression storage is one of the dynamic components of the rainfall-runoff process. The quantification of the effect of rainfall intensity and duration on the micro-relief was the subject of this study. Micro-relief measurements were made on 88 soil bin samples before and after the application of simulated rainfall events. The surface depression changes are described with empirical equations, using basic rainfall, surface hydrology, and soil parameters and their cross products as independent variables. A rainfall-runoff model demonstrates the value of a dynamic description of the surface depression storage function.