29 CARDIOVASCULAR COLLAPSE AND SUDDEN DEATH
Harrison’s Manual of Medicine
CARDIOVASCULAR COLLAPSE AND SUDDEN DEATH
Management of Cardiac Arrest
Unexpected cardiovascular collapse and death most often result from ventricular fibrillation in pts with underlying coronary artery disease, with or without acute MI. Other common causes are listed in Table 29-1. The arrhythmic causes may be provoked by electrolyte disorders (primarily hypokalemia), hypoxemia, acidosis, or massive sympathetic discharge, as may occur in CNS injury. Immediate institution of cardiopulmonary resuscitation (CPR) followed by advanced life support measures (see below) are mandatory. Ventricular fibrillation, or asystole, without institution of CPR within 4–6 min, usually causes death.
Table 29-1 Differential Diagnosis of Cardiovascular Collapse and Sudden Death
Management of Cardiac Arrest
Basic life support (BLS) commences immediately (Fig. 29-1):
FIGURE 29-1. Major steps in cardiopulmonary resuscitation. A. Make certain the victim has an open airway. B. Start respiratory resuscitation immediately. C. Feel for the carotid pulse in the groove alongside the “Adam’s apple” or thyroid cartilage. D. If pulse is absent, begin cardiac massage. Use 60 compressions/min with one lung inflation after each group of 5 chest compressions when two people are performing resuscitation or twice in rapid succession for every 15 compressions when one person performs both ventilation and compression. (From J Henderson, Emergency Medical Guide, 4th ed, New York, McGraw-Hill, 1978.)
1. Open mouth of patient and remove visible debris or dentures. If there is respiratory stridor, consider aspiration of a foreign body and perform Heimlich maneuver.
2. Tilt head backward, lift chin, and begin mouth-to-mouth respiration if rescue equipment is not available (pocket mask is preferable to prevent transmission of infection). The lungs should be inflated once for every 5 chest compressions when two persons are performing resuscitation or twice in rapid succession for every 15 chest compressions when one person performs both ventilation and chest compression.
3. If carotid pulse is absent, perform chest compressions (depressing sternum 3–5 cm) at rate of 80–100 per min. For one rescuer, 15 compressions are performed before returning to ventilating twice.
As soon as resuscitation equipment is available, begin advanced life support (Fig. 29-2) with continued chest compressions and ventilation. Although performed as simultaneously as possible, defibrillation takes highest priority, followed by placement of intravenous access and intubation. 100% O2 should be administered by endotracheal tube or, if rapid intubation cannot be accomplished, by bag-valve-mask device; respirations should not be interrupted for more than 30 s while attempting to intubate. Initial intravenous access should be through the antecubital vein, but if drug administration is ineffective, a central line (internal jugular or subclavian) should be placed. Intravenous NaHCO3 should be administered only if there is persistent severe acidosis (pH < 7.15) despite adequate ventilation. Calcium is not routinely administered but should be given to pts with known hypocalcemia, those who have received toxic doses of calcium channel antagonists, or if acute hyperkalemia is thought to be the triggering event for resistant ventricular fibrillation.
FIGURE 29-2. Advanced life support algorithm. *Antecubital route preferred; if infusions not effective, place central line. †If hypomagnesemic state or if rhythm is torsades de pointes. †Do not infuse sodium bicarbonate in same IV as calcium, epinephrine, or dopamine. LVEF, left ventricular ejection fraction; VF, ventricular fibrillation; VT, ventricular tachycardia; PEA, pulseless electrical activity (formerly termed electromechanical dissociation); SVT, supraventricular tachycardia. [Modified from American Heart Association Circulation 102 (Suppl I): I-142–157, 2000.]
If cardiac arrest was due to ventricular fibrillation in initial hours of an acute MI, follow-up is standard post-MI care (Chap. 121). For other survivors of a ventricular fibrillation arrest, extensive evaluation, including evaluation of coronary anatomy, left ventricular function, and invasive electrophysiologic testing, is recommended. Long-term antiarrhythmic drug therapy, implantation of an automatic defibrillator, and/or cardiac surgery (coronary artery bypass graft, aneurysmectomy, or resection/ablation of arrhythmic foci) may be necessary.
For a more detailed discussion, see Myerburg RJ, Castellanos A: Cardiovascular Collapse, Cardiac Arrest, and Sudden Death, Chap. 39, p. 228, in HPIM-15.