Leroy C. Harris

Augmentation of Artificial Circulation During Cardiopulmonary Resuscitation

Experiments in dogs with ventricular fibrillation were carried out to determine the effects of epinephrine, plasma volume expansion and manual pressure over the abdomen upon carotid flow and arterial pressure during external cardiac compressions. Epincphrine given intravenously produced a significant increase in systolic arterial pressure but no significant change in carotid flow. Epinephrine given subcutaneously over the sternum in 2 mg. increments had no effect on either systolic pressure or carotid flow. Both intravenously and intra-arterially administered dextran 75 improved carotid flow during external cardiac compressions, both routes being equally effective. Volume expansion, therefore, is indicated during external cardiac compressions even in normovolemic subjects, provided there is no pulmonary edema. Constant manual pressure exerted over the upper abdomen during external cardiac compressions produced a significant increase in carotid flow, but is not recommended because it promoted rupture of the liver.

Ventilation—Cardiac Compression Rates and Ratios in Cardiopulmonary Resuscitation

Ventilation-compression frequencies and ratios during cardiopulmonary resuscitation in dogs with ventricular fibrillation and ventilation frequencies in apneic healthy human subjects were studied. Lung inflations interposed between sternal compressions gave better ventilation and about equal carotid blood flows as compared to simultaneous inflations. A ventilation—compression ratio of 3/15 (using air) maintained normal oxygenation and ventilation, whereas 6/30 did not In apneic adults with two inflations (tidal volume 1,000 ml) every 15 seconds, oxygenation and ventilation were adequate with FiO26O compressions per minute, while 120 compressions per minute gave insignificantly greater flows than 72 compressions per minute. The recommendation of a ventilation—compression ratio of 2/15 for one operator and 1/5 interposed for two operators (compressions at one second intervals without interruption) is sound.

TREATMENT OF EXSANGUINATING HEMORRHAGE

Principal treatment consists of prompt hemostasis and transfusion of bank blood. Additional therapeutic concepts under investigation by othrs include : Oxygen and controlled hyperventilation (because of increased physiologic dead space and decreased oxygen transport) ; use sf vasodilators (in prolonged shock with splanchnic vasoconstriction) ; use of vasoconstrictors (in threatened cardiac arrest) ; alkalinizing agents (in prolonged shock with low plasma pH) ; warm blood and calcium (in massive transfusion); balanced salt solution (to combat extracellular fluid loss in tissue trauma) ; heparin and fibrinolysin (to prevent and combat intravascular clotting) ; low molecular weight dextran (to promote capillary flow) ; steroids; and hypothermia. Additional therapeutic concepts are under investigation in dogs in our laboratory. Preliminary results are presented below.