Median frequency--a new parameter for predicting defibrillation success rate.

Study Hypothesis: Current American Heart Association guidelines recommend immediate defibrillation of ventricular fibrillation. When this is unsuccessful, there are no guidelines to help determine the optimum time at which to defibrillate after the administration of an alpha-adrenergic agonist. Previous studies have shown that the median frequency of the ventricular fibrillation ECG signal correlates with myocardial perfusion during CPR.

Hemodynamic effects of 1-[3,4-dihydroxyphenyl]-1,2-diaminoethane versus norepinephrine during ventricular fibrillation and cardiopulmonary resuscitation.

We hypothesized that substitution of the hydroxyl group (OH) on the beta carbon of norepinephrine (NE) with an amino group would yield a compound, 1-(3,4-dihydroxyphenyl)-1,2-diaminoethane (DHPDAE), that would maintain the hemodynamic properties of NE during CPR, but would decrease the rate of post-defibrillation dysrhythmias. Six mixed breed swine weighing greater than 28 kg were studied. The animals were instrumented for cerebral (CBF) and myocardial blood flow (MBF) measurements.

Time dependency of endotoxin-induced resistance to transplantable tumors in mice.

A single injection of bacterial endotoxin induced cyclic changes of enhanced or reduced host reactivities, as determined in some measurements of the beneficial effects of endotoxin, such as immune potentiation or protection against lethal irradiation. The results described here show that endotoxin-induced resistance to subsequent challenge with transplantable tumors such as Lewis lung carcinoma or L1210 murine leukemia is similarly time dependent. While certain time intervals between endotoxin treatment and tumor challenge will provide significant protection, others will render the recipients highly susceptible to the same tumor.