Engineering Commons^™

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 …

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).

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 …

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 …

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 …