The Journal of Thoracic and Cardiovascular Surgery, Vol 76, 244-251, Copyright © 1978 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Optimizing myocardial supply/demand balance with alpha-adrenergic drugs during cardiopulmonary resuscitation
JJ Livesay, DM Follette, KH Fey, RL Nelson, EC DeLand, RJ Barnard and GD Buckberg
In 14 dogs the determinants of myocardial blood supply and metabolic
demands were assessed during cardiopulmonary resuscitation (CPR) and under
steady-state conditions in fibrillating hearts on cardiopulmonary bypass.
During open chest cardiac massage (nine dogs), coronary diastolic blood
pressure and blood flow were low. Vasopressor infusion (methoxamine or
epinephrine) raised diastolic pressure from 33 +/- 3 to 55 +/- 3 mm. Hg and
increased coronary blood flow (CBF) 124 percent (from 38 +/- 3 to 85 +/- 11
c.c. per 100 Gm. per minute. Comparison of these drugs in fibrillating
hearts on cardiopulmonary bypass showed that epinephrine increased the
"vigor of fibrillation" (intraventricular balloon pressure rose 24 percent
and oxygen uptake increased 42%) but impeded subendocardial flow 53%
(endocardial/epicardial flow ratio fell from 0.79 to 0.48). In contrast,
methoxamine did not significantly change intraventricular balloon pressure,
oxygen uptake, coronary flow, or its distribution. We conclude that
augmentation of diastolic pressure with alpha adrenergic drugs during CPR
improves coronary perfusion and that inotropic drugs may worsen myocardial
ischemia during CPR by raising oxygen demands while simultaneously impeding
subendocardial blood supply.