When an individual suddenly collapses, first quickly check for pulse or heartbeat. If one is present, raise the victim's legs two feet above the plane of the reclining body (to augment fluid return to the central circulation); then, call for medical assistance. If there is no pulse, immediately suspect Cardiac Arrest. Check the airway for obstruction and clear it. Because most victims resuscitated from cardiac arrest have ventricular tachycardia or ventricular fibrillation, assume that is the problem and follow one of these two procedures: Cough or Thump...

If the victim is conscious and capable, he or she should be encouraged to cough vigorously once or twice. Forceful coughs have been shown to transmit a small amount of current to the heart capable of terminating these catastrophic dysrhythmias and allowing for an effective cardiac rhythm to be reestablished. This maneuver is especially suited for self-administration; a patient with known cardiac disease who suddenly feels palpitations in the chest followed by lightheadedness and the feeling of impending loss of consciousness could do little harm by bringing forth one or two vigorous coughs. During the cough's inspiratory phase, the downward movement of the diaphragm facilitates the return of blood from the body to the heart's right ventricle and even oxygenates the blood flowing through the lungs at that time. During the expiratory phase, contraction of the abdominal muscles forces the diaphragm into the chest cavity, generating high pressures that are applied to the heart and its associated large blood vessels, which in turn propels blood through the open heart valves to the brain and other organs.

If the patient is not capable of coughing, one or two thumps to the mid chest can be given with a clenched fist within no more than one minute of collapse. The thump should be applied from six to eight inches above the chest and directed at an area about two thirds of the distance down the breastbone. Should the first blow not result in a pulse, a second, stronger blow should be given immediately. The thump can also be self-administered. It is not known how the thump procedure works, although it is suspected that the thump causes a mechanoelectrical stimulus that terminates the undesirable rhythm disturbance.