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Articles 1 - 11 of 11
Full-Text Articles in Biomedical Engineering and Bioengineering
Methods For Calculating Coronary Perfusion Pressure During Cpr, Michael P. Otlewski, Leslie A. Geddes, Michael Pargett, Charles F. Babbs
Methods For Calculating Coronary Perfusion Pressure During Cpr, Michael P. Otlewski, Leslie A. Geddes, Michael Pargett, Charles F. Babbs
Weldon School of Biomedical Engineering Faculty Publications
Coronary perfusion pressure (CPP) is a major indicator of the effectiveness of cardiopulmonary resuscitation in human and animal research studies; however methods for calculating CPP differ among research groups. Here we compare the 6 published methods for calculating CPP using the same data set of aortic (Ao) and right atrial (RA) blood pressures. CPP was computed using each of the 6 calculation methods in an anesthetized pig model, instrumented with catheters with Cobe pressure transducers. Aortic and right atrial pressures were recorded continuously during electrically induced ventricular fibrillation and standard CPR. CPP calculated from the same raw data set by …
Effect Of Deferoxamine On Late Deaths Following Cpr In Rats, Charles F. Babbs, Sushil D. Kompala, Karl E. Blaho
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 …
Potassium Efflux From Myocardial Cells Induced By Defibrillator Shock, M J. Niebauer, L A. Geddes, Charles F. Babbs
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 …
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
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 …
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
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, …
Improved Oxygen Delivery During Cardiopulmonary Resuscitation With Interposed Abdominal Compressions, William D. Voorhees, Mark J. Niebauer, Charles F. Babbs
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, …
Cardiopulmonary Resuscitation With Interposed Abdominal Compression In Dogs, Sandra H. Ralston, Charles F. Babbs, Mark J. Niebauer
Cardiopulmonary Resuscitation With Interposed Abdominal Compression In Dogs, Sandra H. Ralston, Charles F. Babbs, Mark J. Niebauer
Weldon School of Biomedical Engineering Faculty Publications
This study was conducted to evaluate the hemodynamic effectiveness of a new modification of cardiopulmonary resuscitation (CPR), termed interposed abdominal compression- CPR (IAC-CPR). IAC-CPR utilizes all the steps of standard CPR with the addition of abdominal compressions interposed during the release phase of chest compression. Ventricular fibrillation was induced electrically in 10 anesthetized dogs, and either IAC-CPR or standard CPR was initiated while arterial and venous blood pressures and cardiac output were monitored. The two CPR methods were alternated every three minutes over a period of thirty minutes. The addition of interposed abdominal compressions to standard CPR improved arterial pressures …
Transchest Defibrillation Under Conditions Of Hypothermia, W A. Tacker, Charles F. Babbs, D R. Abendschein, L A. Geddes
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 …
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
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, …
Evaluation Of The Operating Internal Resistance And Capacitance Of Intact Trapezoidal Waveform Defibrillators, Charles F. Babbs, Sj Whistler, La Geddes
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.
Effect Of Pentobarbital Anesthesia On Ventricular Defibrillation Threshold In Dogs, Charles F. Babbs
Effect Of Pentobarbital Anesthesia On Ventricular Defibrillation Threshold In Dogs, Charles F. Babbs
Weldon School of Biomedical Engineering Faculty Publications
The effect of pentobarbital anesthesia upon the minimal voltage and current required for electrical ventricular defibrillation (the defibrillation threshold) was investigated in dogs. Threshold current, energy, and charge in five dogs averaged 2 per cent, 13 per cent, and 6 per cent less under surgical levels of pentobarbital anesthesia than thresholds in the same animals in the awake, unanesthetized state. In dogs given sufficient pentobarbital to produce apnea and supported by mechanical ventilation, threshold current, energy, and charge averaged 3 per cent, 17 per cent, and 2 per cent less than comparable awake values. These differences were far from statistically …