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Biomedical Engineering and Bioengineering Commons™

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2005

Weldon School of Biomedical Engineering Faculty Publications

Articles 1 - 6 of 6

Full-Text Articles in Biomedical Engineering and Bioengineering

Optimal Control Theory Applied To A Difference Equation Model Of Cardiopulmonary Resuscitation, Eunok Jung, Charles F. Babbs, Suzanne Lenhart, Vladimir A. Protopoescu Oct 2005

Optimal Control Theory Applied To A Difference Equation Model Of Cardiopulmonary Resuscitation, Eunok Jung, Charles F. Babbs, Suzanne Lenhart, Vladimir A. Protopoescu

Weldon School of Biomedical Engineering Faculty Publications

Objective: To apply the mathematical techniques of optimal control theory (OCT) to a validated model of the human circulation during cardiopulmonary resuscitation (CPR), so as to discover improved waveforms for chest compression and decompression that maximize the systemic perfusion pressure (SPP). Methods: The human circulatory system is represented by seven difference equations, which describe the pressure changes in systemic vascular compartments caused by chest compression. The forcing term is the intrathoracic pressure generated by the external chest compression, which is taken as the “control” variable for the system. The optimum waveform of this forcing pressure as a function of time, …

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A Dose-Response Curve For The Negative Bias Pressure Of An Intrathoracic Pressure Regulator During Cpr, Charles F. Babbs, Demetris Yannopoulos Oct 2005

A Dose-Response Curve For The Negative Bias Pressure Of An Intrathoracic Pressure Regulator During Cpr, Charles F. Babbs, Demetris Yannopoulos

Weldon School of Biomedical Engineering Faculty Publications

An intrathoracic pressure regulator (ITPR) is a device that can be added to the external end of an endotracheal tube to create controlled negative airway pressure between positive pressure ventilations. The resulting downward bias of the airway pressure baseline promotes increased venous return and enhanced circulation during CPR and also during hypovolemic shock. In the present study we exercised a mathematical model of the human cardiopulmonary system, including airways, lungs, a 4 chambered heart, great vessels, peripheral vascular beds, and the biomechanics of chest compression and recoil, to determine the relationship between systemic perfusion pressure during CPR and the value …

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Intravenous Polyethylene Glycol Inhibits The Loss Of Cerebral Cells After Brain Injury, Andrew O. Koob, Bradley S. Duerstock, Charles F. Babbs, Yinlong Sun, Richard B. Borgens Oct 2005

Intravenous Polyethylene Glycol Inhibits The Loss Of Cerebral Cells After Brain Injury, Andrew O. Koob, Bradley S. Duerstock, Charles F. Babbs, Yinlong Sun, Richard B. Borgens

Weldon School of Biomedical Engineering Faculty Publications

We have tested the effectiveness of polyethylene glycol (PEG) to restore the integrity of neuronal membranes after mechanical damage secondary to severe traumatic brain injury (TBI) produced by a standardized head injury model in rats. We provide additional detail on the standardization of this model, particularly the use and storage of foam bedding that serves to both support the animal during the impact procedure and to dampen the acceleration of the brass weight. Further, we employed a dye exclusion technique using ethidium bromide (EB; quantitative evaluation) and horseradish peroxidase (HRP; qualitative evaluation). Both have been successfully used previously to evaluate …

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Biophysics Of Cardiopulmonary Resuscitation With Periodic Z-Axis Acceleration Of Abdominal Compression At Aortic Resonant Frequencies, Charles F. Babbs Sep 2005

Biophysics Of Cardiopulmonary Resuscitation With Periodic Z-Axis Acceleration Of Abdominal Compression At Aortic Resonant Frequencies, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Periodic z-axis acceleration (pGz)-CPR involves oscillating motion of a whole patient in the head-to-foot dimension on a mechanized table. The method is able to sustain blood flow and long-term survival during and after prolonged cardiac arrest in anesthetized pigs. However, the exact mechanism by which circulation of blood is created has remained unknown. Objectives: To explain the hemodynamic mechanism of pGz-CPR and to suggest theoretically useful improvements. Method: Computer modeling using a hybrid analytical-numerical approach, based upon Newton’s second law of motion for fluid columns in the aorta and vena cavae, Ohm’s law for resistive flow through vascular beds, and …

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Effects Of An Impedance Threshold Valve Upon Hemodynamics In Standard Cpr: Studies In A Refined Computational Model, Charles F. Babbs Mar 2005

Effects Of An Impedance Threshold Valve Upon Hemodynamics In Standard Cpr: Studies In A Refined Computational Model, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

An impedance threshold valve (ITV) is a new airway adjunct for resuscitation that permits generation of a small vacuum in the chest during the recoil phase of chest compression. Objectives: To explore in detail the expected magnitude and the hemodynamic mechanisms of circulatory augmentation by an ITV in standard CPR. Method: A 14-compartment mathematical model of the human cardiopulmonary system—upgraded to include applied chest compression force, elastic recoil of the chest wall, anatomic details of the heart and lungs, and the biomechanics of mediastinal compression—is exercised to explore the conditions required for circulatory augmentation by an ITV during various modes …

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Relative Effectiveness Of Interposed Abdominal Compression Cpr: Sensitivity Analysis And Recommended Compression Rates, Charles F. Babbs Jan 2005

Relative Effectiveness Of Interposed Abdominal Compression Cpr: Sensitivity Analysis And Recommended Compression Rates, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Interposed abdominal compression (IAC)-CPR incorporates alternating chest and abdominal compressions to generate enhanced artificial circulation during cardiac arrest. The technique has been generally successful in improving blood flow and survival compared to standard CPR; however some questions remain. Objective: To determine "why does IAC-CPR produce more apparent benefit in some subjects than in others? and "what is the proper compression rate, given that there are actually two compressions (chest and abdomen) in each cycle?" Method: Computer models provide a means to search for subtle effects in complex systems. The present study employs a validated 12-compartment mathematical model of the human …

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