CARDIAC RESUSCITATION BY RETROAORTIC INFUSION OF BLOOD

Current methods of closed-chest cardiac resuscitation generate coronar y perfusion pressures that rarely exceed one fourth of normal, and thi s decreases with prolongation of cardiac arrest. The resuscitation eff ort is therefore almost uniformly unsuccessful when precordial compres sion is initiated after 8 minutes of untreated cardiac arrest. This re port introduces a new option for cardiac resuscitation by infusion of oxygenated blood into the ascending aorta such as to transiently incre ase the pressure gradient for coronary perfusion. Thirty-six anestheti zed, mechanically ventilated normovolemic rats were investigated. Card iac arrest was induced with an alternating current delivered through a n electrode catheter advanced into the right ventricle. Ventricular fi brillation was untreated for 4, 6, or 8 minutes, after which resuscita tion was attempted without blood infusion, with infusion of oxygenated blood, or with infusion of oxygenated blood containing 30 mg/kg epine phrine. The boluses of blood were delivered through a catheter advance d from the right carotid artery into the ascending aorta. Except for m echanical ventilation and direct current precordial countershock for e lectrical defibrillation, no other mechanical resuscitation interventi on, and specifically no precordial compression, was administered. None of six control animals that received either no retroaortic infusion o r right atrial infusion was resuscitated after 4 minutes of untreated ventricular fibrillation. Each of five animals was successfully resusc itated by retroaortic infusion after 4 minutes of untreated cardiac ar rest; one was resuscitated after 6 minutes, and none wets resuscitated after 8 minutes. When epinephrine was added to donor blood, each of f ive animals was successfully resuscitated by bolus ascending aortic in jections after 4, 6, and 8 minutes of untreated cardiac arrest. Succes sful resuscitation was closely related to the extent to which the bolu ses increased coronary perfusion pressure. Retroaortic infusion of oxy genated blood and especially blood containing epinephrine, which marke dly increased coronary perfusion pressure, was an effective alternativ e to precordial compression for cardiac resuscitation in a murine mode l after prolonged cardiac arrest.