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Articles 361 - 390 of 417

Full-Text Articles in Biomedical Engineering and Bioengineering

Protection From Reperfusion Injury In The Isolated Rat Heart By Postischaemic Deferoxamine And Osypurinol Administration, Stephen F. Badylak, Abby Simmons, John Turek, Charles F. Babbs Jan 1987

Protection From Reperfusion Injury In The Isolated Rat Heart By Postischaemic Deferoxamine And Osypurinol Administration, Stephen F. Badylak, Abby Simmons, John Turek, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

The Langendorff isolated rat heart preparation was used to determine the effect of oxypurinol, a xanthine oxidase inhibitor, and deferoxamine, an iron binding agent, on the extent of myocardial reperfusion injury after 60 minutes of ischaemia. Thirty rats were divided into three groups of 10. and an isolated heart preparation made from each rat. The isolated hearts were perfused for 15 minutes with a modified Krebs-Henseleit perfusate solution to permit stabilisation of the preparation. Each heart was then subjected to 60 minutes of total ischaemia at 37°C followed by 60 minutes of reperfusion with either saline treated perfusate, oxypurinol treated …

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A Predictive-Adaptive, Multipoint Feedback Controller For Local Heat Therapy Of Solid Tumors, Charles F. Babbs, V A. Vanguine, J T. Jones May 1986

A Predictive-Adaptive, Multipoint Feedback Controller For Local Heat Therapy Of Solid Tumors, Charles F. Babbs, V A. Vanguine, J T. Jones

Weldon School of Biomedical Engineering Faculty Publications

Uniform heating of tumor tissue to therapeutic temperatures without damaging surrounding normal tissue is required for optimal local heat therapy of cancer. This paper describes an algorithm for online computer control that will allow the therapist to minimize the standard deviation of measured intratumoral temperatures. The method is applicable to systems incorporating multiple surface and/or interstitial applicators delivering microwave, radiofrequency, or ultrasonic power and operating under the control of a small computer. The essential element is a novel predictive-adaptive control algorithm that infers relevant thermal parameters from the responses of multiple temperature sensors, as each of the power applicators is …

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Effect Of Deferoxamine On Late Deaths Following Cpr In Rats, Charles F. Babbs, Sushil D. Kompala, Karl E. Blaho Jan 1986

Effect Of Deferoxamine On Late Deaths Following Cpr In Rats, Charles F. Babbs, Sushil D. Kompala, Karl E. Blaho

Weldon School of Biomedical Engineering Faculty Publications

The iron chelating agent deferoxamine was studied in an animal model as post-resuscitation therapy to prevent late deaths and brain damage following total circulatory arrest and resuscitation. Cardio-respiratory arrest was induced by injection of cold, 1% KC1 into the left ventricles of ketamine anesthetized rats pretreated with succinylcholine chloride, and by discontinuation of positive pressure ventilation. CPR was begun after six minutes, and animals with return of spontaneous circulation were entered into the study. Within five minutes after return of spontaneous circulation, treated animals received deferoxamine (50 mg/kg, IV). At ten days, 16 of 25 (64%) of treated animals had …

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Relationship Between Pulse-Wave Velocity And Arterial Elasticity, F J. Callaghan, L A. Geddes, Charles F. Babbs, J D. Bourland Jan 1986

Relationship Between Pulse-Wave Velocity And Arterial Elasticity, F J. Callaghan, L A. Geddes, Charles F. Babbs, J D. Bourland

Weldon School of Biomedical Engineering Faculty Publications

Pulse wave velocity (PWV) was measured in situ in 11 isolated canine common carotid arteries. Seven arteries exhibited a linear PWV vs. pressure function at pressures ranging from 0 to 200 mmHg. Four arteries yielded a linear relationship between PWV and pressure between 1 and 100 mmHg; for these vessels the relationship was nonlinear at higher pressures. Seven arteries (five from the group which was linear up to 200 mmHg and two from the group which was linear up to 100 mmHg) were excised and pressure/volume measurements were made in vivo. Using pressure/volume data, the Moens-Korteweg equation was evaluated as …

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Potassium Efflux From Myocardial Cells Induced By Defibrillator Shock, M J. Niebauer, L A. Geddes, Charles F. Babbs Jan 1986

Potassium Efflux From Myocardial Cells Induced By Defibrillator Shock, M J. Niebauer, L A. Geddes, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

A transient, dose-dependent cardiac depression was produced by defibrillator shocks in an isolated, working canine heart preparation perfused with oxygenated arterial blood from a support dog. Accompanying this depression was an efflux of potassium (K+ ), forced out of the myocardial cells by the passage of defibrillating current. The transient increase in extracellular K + concentration was recorded graphically in the venous outflow. It was found that 5-msec rectangular wave shocks, from three to ten times defibrillatory current threshold, released doserelated pulses of K+ . We conclude that because extracellular K + is a myocardial depressant, at least part of …

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The Effect Of Carbon Dioxide, Lidoflazine, And Deferoxamine Upon Long Term Survival Following Cardiorespiratory Arrest In Rats, Stephen F. Badylak, Charles F. Babbs Jan 1986

The Effect Of Carbon Dioxide, Lidoflazine, And Deferoxamine Upon Long Term Survival Following Cardiorespiratory Arrest In Rats, Stephen F. Badylak, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This study examined the effect of carbon dioxide, lidoflazine, and deferoxamine therapy upon the 10-day survival incidence and subsequent neurologic function of rats subjected to 7 min of cardiorespiratory arrest with resuscitation. Cardiac arrest (asystole) was induced at time zero by injection of cold, 1% KCl into the left ventricle of ketamine-anesthetized rats pretreated with succinylcholine. Positive pressure ventilation was discontinued at time zero. Cardiopulmonary resuscitation (CPR) was begun at 7 min, and animals with return of spontaneous circulation were entered into the study. Twenty treated rats were ventilated for 1 h with 7% carbon dioxide-93% oxygen and given lidoflazine …

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Abdominal Binding And Counterpulsation In Cardiopulmonary Resuscitation, Charles F. Babbs, William E. Blevins Jan 1986

Abdominal Binding And Counterpulsation In Cardiopulmonary Resuscitation, Charles F. Babbs, William E. Blevins

Weldon School of Biomedical Engineering Faculty Publications

The history and potential of abdominal pressure as an adjunct to standard cardiopulmonary resuscitation (CPR) is reviewed. Abdominal pressure during CPR may be either static or phasic. Static abdominal pressure redirects limited blood flow generated by chest compressions toward the heart and brain, and away from the abdominal organs and lower extremities, thus boosting coronary perfusion pressure. Phasic abdominal pressure applied whenever chest pressure is released, in counterpoint to the rhythm of chest compression—so called interposed abdominal compression (IAC)-CPR—generates blood flow by an independent abdominal pump mechanism that augments the systemic perfusion created by chest compressions. New imaging data are …

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Writing A Scientific Paper Prior To The Research, Charles F. Babbs, Martha M. Tacker Jan 1985

Writing A Scientific Paper Prior To The Research, Charles F. Babbs, Martha M. Tacker

Weldon School of Biomedical Engineering Faculty Publications

The traditional approach to preparing a research report for publication is to begin writing after the study has been completed. We propose another approach- to write a "zeroth" draft before the study is begun. This approach helps to focus the investigator's attention during the planning stage on critical aspects of the study. The discipline of writing down the rationale, the methods, and the variety of possible outcomes and their significance helps to clarify the logic on which the study is based. If these are acceptable to all authors and colleagues in the zeroth draft, it is likely that the research …

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An Inspiration-Triggered Delivery System For Oxygen Therapy Via A Nasal Cannula, Philip Charles Krause, Charles F. Babbs Jan 1985

An Inspiration-Triggered Delivery System For Oxygen Therapy Via A Nasal Cannula, Philip Charles Krause, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Therapy for severe chronic lung disease currently includes the administration of supplemental oxygen to prevent breathlessness and tissue hypoxia. Although effective, this therapy is unnecessarily costly, because oxygen is administered to the patient during expiration as well as inspiration. To eliminate this inefficiency, a delivery system that senses the inspiratory effort and delivers oxygen to the patient only during inspiration was developed. The 11  5  8-cm flow control unit attaches easily to a portable oxygen supply. The components of the system have an expected life of five years, and the 9-Volt battery provides power for about one month …

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Use Of Combined Systemic Hypothermia And Local Heat Treatment To Enhance Temperature Differences Between Tumor And Normal Tissues, Charles F. Babbs, William D. Voorhees Iii, Robert R. Clark, David P. Dewitt Jan 1985

Use Of Combined Systemic Hypothermia And Local Heat Treatment To Enhance Temperature Differences Between Tumor And Normal Tissues, Charles F. Babbs, William D. Voorhees Iii, Robert R. Clark, David P. Dewitt

Weldon School of Biomedical Engineering Faculty Publications

The feasibility of combining local heat treatment with wholebody hypothermia in an effort to improve therapeutic gain was assessed. Superficial, non perfused phantom tumors were fashioned in eight anesthetized mongrel dogs by transplantation of the spleen from the abdomen to a subcutaneous site on the hind limb. After pretreatment of the animal with the vasodilator hydralazine (0.5 mg/kg, IV) to enhance normal tissue perfusion, the spleen implant was heated with a 2450-MHz microwave diathermy apparatus, first with the animal's core body temperature in the normal range (39°C) and then after the animal had been packed in ice to reduce core …

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Endotracheal Versus Intravenous Epinephrine During Electromechanical Dissociation With Cpr In Dogs, Sandra H. Ralston, Willis A. Tacker, Lee Showen, Alice B. Carter, Charles F. Babbs Jan 1985

Endotracheal Versus Intravenous Epinephrine During Electromechanical Dissociation With Cpr In Dogs, Sandra H. Ralston, Willis A. Tacker, Lee Showen, Alice B. Carter, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

The dose-response curves of epinephrine given either IV or endotracheally (ET) were compared during resuscitation from electromechanical dissociation (EMD). Ten anesthetized dogs were subjected to a two-minute period of electrically induced ventricular fibrillation (VF) followed by defibrillation without CPR to produce EMD. Mechanical CPR was followed by injection of either ET or IV epinephrine. Successful response was defined as a return of pulsatile blood pressure within two minutes of drug administration. Using log-dose increments of epinephrine, experimental trials were repeated in each animal. The IV and ET median effective doses were 14 and 130 g/kg, respectively. When the trials were …

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Gastric Insufflation During Iac-Cpr And Standard Cpr In A Canine Model, Charles F. Babbs, William E. Schoenlein, Marc W. Lowe Jan 1985

Gastric Insufflation During Iac-Cpr And Standard Cpr In A Canine Model, Charles F. Babbs, William E. Schoenlein, Marc W. Lowe

Weldon School of Biomedical Engineering Faculty Publications

This study was undertaken to determine the effect of interposed abdominal compressions (IAC) during cardiopulmonary resuscitation (CPR) on gastric insufflation when the airway is not secured with an endotracheal tube. A canine model was used in which a common ventilation pressure was applied to separate cuffed esophageal and tracheal tubes. Gas entering the stomach was collected by a pre-placed gastrostomy tube leading to a bell spirometer. Gas entering the lungs was measured with a Wright Respirometer® in series with the endotracheal tube. During standard CPR, measurable gastric gas volume was collected in 28 of 30 trials (mean 215  93 …

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Electroventilation, L A. Geddes, William D. Voorhees, Charles F. Babbs, J A. Deford Jan 1985

Electroventilation, L A. Geddes, William D. Voorhees, Charles F. Babbs, J A. Deford

Weldon School of Biomedical Engineering Faculty Publications

Electroventilation is a term used to describe the production of inspiration by applying rhythmic bursts of short duration stimuli to extrathoracic electrodes to stimulate motor nerves to the inspiratory muscles. In the dog, the optimum site for the electrodes was found to be on the upper chest wall, bilaterally. The inspired volume increased with increasing current intensity. The maximum tidal volume attainable was about four times resting tidal volume. The ability of electroventilation to maintain arterial blood oxygen saturation without the production of cardiac arrhythmias was demonstrated in pentobarbital-anesthetized dogs. The technique has several potential applications and offers promise in …

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Joseph S. Redding's Contributions To Cardiac Resuscitation, Sandra H. Ralston, Charles F. Babbs Jan 1985

Joseph S. Redding's Contributions To Cardiac Resuscitation, Sandra H. Ralston, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

The experimental studies conducted by the late Joseph S. Redding over the past three decades with his students and colleagues form the scientific basis for many aspects of present cardiopulmonary resuscitation (CPR). Redding's research was characterized by its elegance, simplicity, common-sense reasoning, and clinical relevance. Much of his work conducted in the 1960's anticipated with uncanny accuracy some of the most actively discussed issues in resuscitation today (Table 1). Most interesting are Redding's classic studies related to diastolic arterial pressure and myocardial perfusion during CPR, abdominal binding, acid-base status, and use of methoxamine versus other adrenergic drugs for cardiac resuscitation. …

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Irradiation-Hyperthermia In Canine Hemangiopericytomas: Large-Animal Model For Therapeutic Response, Ralph C. Richardson, Virgil L. Anderson, William D. Voorhees, William E. Blevins, Tammy K. Inskeep, Wolfgang Janas, Robert E. Shupe, Charles F. Babbs Nov 1984

Irradiation-Hyperthermia In Canine Hemangiopericytomas: Large-Animal Model For Therapeutic Response, Ralph C. Richardson, Virgil L. Anderson, William D. Voorhees, William E. Blevins, Tammy K. Inskeep, Wolfgang Janas, Robert E. Shupe, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Results of irradiation-hyperthermia treatment in 11 dogs with naturally occurring hemangiopericytomas are reported. Similarities of canine and human hemangiopericytomas are described. Orthovoltage X-irradiation followed by microwaveinduced hyperthermia resulted in a 91% objective response rate. A statistical procedure was given to evaluate quantitatively the clinical behavior of locally invasive, nonmetastatic tumors in dogs that were undergoing therapy for control of local disease. The procedure used a small sample size and demonstrated distribution of the data on a scaled response as well as transformation of the data through classical parametric and nonparametric statistical methods. These statistical methods set confidence limits on the …

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An Experimental Circulatory Arrest Model In The Rat To Evaluate Calcium Antagonists In Cerebral Resuscitation, Lawrence De Garavilla, Charles F. Babbs, Willis A. Tacker Jan 1984

An Experimental Circulatory Arrest Model In The Rat To Evaluate Calcium Antagonists In Cerebral Resuscitation, Lawrence De Garavilla, Charles F. Babbs, Willis A. Tacker

Weldon School of Biomedical Engineering Faculty Publications

A circulatory arrest model in the rat was developed for use in cerebral and cardiac resuscitation studies. Whole-body ischemia was produced for 8 to 18 minutes by arresting the heart with a cold potassium chloride cardioplegic solution. Following cardiopulmonary resuscitation, minimal, standardized intensive care was provided. As the duration of ischemia was increased from 8 to 18 minutes, survival immediately following resuscitation decreased from 100% to 25%, and survival at 48 hours after ischemia decreased from 80% to 0%. Thirty per cent of the rats recovering from 11 minutes of ischemia suffered motor seizures. Survival and the incidence of motor …

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Regional Blood Flow During Cardiopulmonary Resuscitation With Abdominal Counterpulsation In Dogs, William D. Voorhees Iii, Sandra H. Ralston, Charles F. Babbs Jan 1984

Regional Blood Flow During Cardiopulmonary Resuscitation With Abdominal Counterpulsation In Dogs, William D. Voorhees Iii, Sandra H. Ralston, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

The addition of abdominal counterpulsation to standard cardiopulmonary resuscitation (IAC-CPR) during ventricular fibrillation has been shown to improve cardiac output, oxygen uptake, and central arterial blood pressure in dogs. The present study was performed to determine the effect of IAC-CPR on regional blood flow. Regional blood flow was measured with radioactively labeled microspheres during sinus rhythm and during alternate periods of IAC-CPR and standard CPR (STD-CPR) in nine dogs anesthetized with pentobarbital. Blood pressures and oxygen uptake were measured continuously. As in previous studies, diastolic arterial pressure was higher (30.8%) during IAC-CPR than during STD-CPR, as were cardiac output (24.5%) …

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Preclinical Studies Of Abdominal Counterpulsation In Cpr, Charles F. Babbs Jan 1984

Preclinical Studies Of Abdominal Counterpulsation In Cpr, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Abdominal counterpulsation added to standard cardiopulmonary resuscitation improves blood flow in animal models when compared to chest compressions alone. Similar effects can be demonstrated in analog and digital computer models of the circulation. The technique generates both central aortic and central venous pressure pulses, and successful application of the method depends on maximizing the former and minimizing the latter. Proper technique is important in order to generate the largest possible arteriovenous pressure difference.

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Abnormal Response Of Tumor Vasculature To Vasoactive Drugs, Rosanna C. Chan, Charles F. Babbs, Richard J. Vetter, Carlton H. Lamar Jan 1984

Abnormal Response Of Tumor Vasculature To Vasoactive Drugs, Rosanna C. Chan, Charles F. Babbs, Richard J. Vetter, Carlton H. Lamar

Weldon School of Biomedical Engineering Faculty Publications

The effects of the vasoconstrictor, phenylephrine, and the vasodilator, hydralazine, on blood flow to tumor were studied and compared to those on blood flow to normal tissues in vivo. Regional blood flow and cardiac output were measured with the use of radioactive microspheres in 150- to 250 g inbred Harlan F344 rats bearing subcutaneous nodules of two types of transplantable carcinoma ("hard" and "soft") with microscopically different vascular patterns. Three groups of rats were treated with hydralazine, saline, or phenylephrine, and regional blood flow was determined at the time of maximum blood pressure response. Results were correlated with quantitative morphometric …

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Cardiac, Thoracic, And Abdominal Pump Mechanisms In Cardiopulmonary Resuscitation: Studies In An Electrical Model Of The Circulation, Charles F. Babbs, Christopher Weaver, Sandra H. Ralston, Leslie A. Geddes Jan 1984

Cardiac, Thoracic, And Abdominal Pump Mechanisms In Cardiopulmonary Resuscitation: Studies In An Electrical Model Of The Circulation, Charles F. Babbs, Christopher Weaver, Sandra H. Ralston, Leslie A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

To investigate alternative mechanisms generating artificial circulation during cardiopulmonary resuscitation (CPR), an electrical model of the circulation was developed. Heart and blood vessels were modeled as resistive-capacitive networks; pressures in the chest, abdomen, and vascular compartments as voltages; blood flow as electric current; blood inertia as inductance; and the cardiac and venous valves as diodes. External pressurization of thoracic and abdominal vessels, as would occur in CPR, was simulated by application of half-sinusoidal voltage pulses. Three modes of creating artificial circulation were studied: cardiac pump (CP), in which the atria and ventricles of the model were pressurized simultaneously; thoracic pump …

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Intrapulmonary Epinephrine During Prolonged Cardipulmonary Resuscitation: Improved Regional Blood Flow And Resuscitation In Dogs, Sandra H. Ralston, William D. Voorhees, Charles F. Babbs Jan 1984

Intrapulmonary Epinephrine During Prolonged Cardipulmonary Resuscitation: Improved Regional Blood Flow And Resuscitation In Dogs, Sandra H. Ralston, William D. Voorhees, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Blood flow to vital organs was measured at five-minute intervals during 20 minutes of cardiopulmonary resuscitation (CPR) and ventricular fibrillation in two groups of anesthetized dogs (n = 15 per group). The relationship between organ blood flow and restoration of circulation after 20 minutes was assessed with no additional treatment in Group I and with intrapulmonary epinephrine in Group II. Cardiac output and organ blood flow did not vary significantly in Group I. In Group II, intrapulmonary epinephrine significantly improved blood flow to the myocardium, the brain, and the adrenal glands. A mean myocardial blood flow of less than 0.13 …

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Theoretical Advantages Of Abdominal Counterpulsation In Cpr As Demonstrated In A Simple Electrical Model Of The Circulation, Charles F. Babbs, Sandra H. Ralston, Leslie A. Geddes Jan 1984

Theoretical Advantages Of Abdominal Counterpulsation In Cpr As Demonstrated In A Simple Electrical Model Of The Circulation, Charles F. Babbs, Sandra H. Ralston, Leslie A. Geddes

Weldon School of Biomedical Engineering Faculty Publications

Animal studies and preliminary clinical observations suggest that the addition of interposed abdominal compressions (IAC) to ventilation and chest compression of standard cardiopulmonary resuscitation (CPR) augments blood flow, blood pressures, and immediate survival. To investigate the physical basis for enhanced circulation during IAC-CPR, we developed an electrical model of the circulation. Heart and blood vessels were modeled as resistive-capacitive networks, pressures as voltages, blood flow as electric current, blood inertia as inductance, and the cardiac and venous valves as diodes. External pressurization of the heart and great vessels, as would occur in CPR, was simulated by application by half-sinusoidal voltage …

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Efficacy And Safety Of The Reciprocal Pulse Defibrillator Current Waveform, M J. Niebauer, Charles F. Babbs, L A. Geddes, J D. Bourland Jan 1984

Efficacy And Safety Of The Reciprocal Pulse Defibrillator Current Waveform, M J. Niebauer, Charles F. Babbs, L A. Geddes, J D. Bourland

Weldon School of Biomedical Engineering Faculty Publications

The efficacy and safety of a new defibrillating current waveform, consisting of a low-tilt 5 ms trapezoidal pulse followed closely by a second identical pulse of opposite polarity, was tested m seven isolated, perfused, working canine hearts suspended in an isoresistive, isosmotic shock bath at 37 oC. The efficacy and safety of the reciprocal pulse was compared with a single 5 ms pulse, a single 10 ms pulse, and a dual (unidirectional) 5 ms pulse waveform. The mean threshold average current densities for the 5 ms single pulse, 10 ms single pulse, dual 5 ms pulse, and reciprocal pulse (absolute …

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Effects Of Myocardial Infarction On Catheter Defibrillation Threshold, Charles F. Babbs Jan 1983

Effects Of Myocardial Infarction On Catheter Defibrillation Threshold, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Because the automatic implantable defibrillator may be used in patients having ischemic heart disease, it is important to know whether myocardial ischemia changes the threshold for ventricular defibrillation under experimental conditions simulating automatic internal defibrillation. We determined changes in ventricular defibrillation threshold following coronary occlusion, using an electrode catheter designed for use with an automatic implantable defibrillator. Acute myocardial ischemia was produced without thoracotomy in 10 dogs (experimental group) by embolization with a plastic bead injected via a catheter into the left coronary artery. A control group of 4 dogs had only saline injected into the artery. Defibrillation threshold was …

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Simple Methods For Determining The Accuracy Of Tumor Blood Flow Measurements Using Radioactive Microspheres In Rats, Rosanna C. Chan, Charles F. Babbs, Richard J. Vetter Jan 1983

Simple Methods For Determining The Accuracy Of Tumor Blood Flow Measurements Using Radioactive Microspheres In Rats, Rosanna C. Chan, Charles F. Babbs, Richard J. Vetter

Weldon School of Biomedical Engineering Faculty Publications

Two simple methods are presented that allow positive identification of the accuracy and precision of the microsphere technique and a quick verification of sphere entrapment in tumor vessels. A known flow of Ringer's solution from a motor-driven syringe is perfused through the rat's isolated systemic circulation from left ventricle to right atrium and collected in a funnel. Using this preparation, total blood flow in rats measured with radioactive microspheres injected into the left ventricle was 97% of actual flow. The coefficient of variation (standard deviation/mean) of the microsphere measurements was 0.22. In the same preparation, non-entrapment of microspheres in subcutaneous …

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Improved Oxygen Delivery During Cardiopulmonary Resuscitation With Interposed Abdominal Compressions, William D. Voorhees, Mark J. Niebauer, Charles F. Babbs Jan 1983

Improved Oxygen Delivery During Cardiopulmonary Resuscitation With Interposed Abdominal Compressions, William D. Voorhees, Mark J. Niebauer, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

The ability of a new modification of cardiopulmonary resuscitation (CPR) to deliver oxygen to tissues was evaluated. The method utilizes standard CPR techniques with the addition of manual abdominal compressions (100 mm Hg) interposed between chest compressions, and is termed interposed abdominal compression-CPR (IAC-CPR). Oxygen delivery was measured by a spirometer in a closed circuit designed to permit positive-pressure ventilation synchronized with mechanical chest compression. Ventricular fibrillation was induced electrically in 10 anesthetized dogs. In each dog, trials of IAC-CPR and standard CPR were alternated every five minutes during a 30-minute period. Arterial and central venous blood pressures, oxygen consumption, …

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Relationship Of Blood Pressure And Flow During Cpr To Chest Compression Amplitude: Evidence For An Effective Compression Threshold, Charles F. Babbs, W D. Voorhees, K R. Fitzgerald, H R. Holmes, L A. Geddes Jan 1983

Relationship Of Blood Pressure And Flow During Cpr To Chest Compression Amplitude: Evidence For An Effective Compression Threshold, 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 investigate the importance of the depth of chest compression in producing effective cardiopulmonary resuscitation (CPR) in animals, as indicated by cardiac output and mean arterial blood pressure. Cardiac output was measured by a modified indicator dilution technique in 8 anesthetized dogs, 6 to 12 kg body weight, during repeated 2-minute episodes of electrically induced ventricular fibrillation and CPR provided by a mechanical chest compressor and ventilator (Thumper®). Chest compression exceeding a threshold value (x0) between 1.5 and 3.0 cm was required in each animal to produce measurable cardiac output. In particular, …

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Equipment For Local Hyperthermia Therapy Of Cancer, Charles F. Babbs, James R. Oleson, John A. Pearce Jan 1982

Equipment For Local Hyperthermia Therapy Of Cancer, Charles F. Babbs, James R. Oleson, John A. Pearce

Weldon School of Biomedical Engineering Faculty Publications

Rapid improvements in hyperthermia apparatus are being achieved by industrial and university-based research groups that have already led to the marketing of a variety of commercial systems for heat therapy of malignancy. These tissue heating systems employ microwaves, capacitively or inductively coupled radiofrequency current, or high intensity ultrasound to produce controlled local heating of tumor tissues. No single system is superior to others in all applications; each has its limitations.

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Characterization Of The Oscillometric Method For Measuring Indirect Blood Pressure, L A. Geddes, M Voelz, C Combs, D Reiner, Charles F. Babbs Jan 1982

Characterization Of The Oscillometric Method For Measuring Indirect Blood Pressure, L A. Geddes, M Voelz, C Combs, D Reiner, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

In this study, human subjects and dogs were used to determine the ability of the oscillometric method to indicate systolic and diastolic pressure. In the human studies, the auscultatory method was used as the reference. In the animal studies, directly recorded blood pressure was used as the reference. The ability of the sudden increase in cuff pressure oscillations during cuff deflation to indicate systolic pressure was examined and found to overestimate systolic pressure slightly in man, but more in animals. Systolic pressure was encountered when the cuff pressure oscillations were about one half of their maximum amplitude. However, in both …

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Biology Of Local Heat Therapy For Cancer, Charles F. Babbs Jan 1982

Biology Of Local Heat Therapy For Cancer, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Successful cancer therapy must selectively destroy tumor tissue while sparing the host's normal tissues. Local heat treatment can have such a selective effect because abnormalities in tumor blood vessels supply less oxygen to heat-stressed tumor cells and are less efficient in cooling tumor tissue by blood perfusion.

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