A 70-year-man developed cardiac arrest from hyperkalemia. Advanced cardiac life support was performed for asystole for 26 minutes while he was treated with calcium gluconate, glucose-insulin, sodium bicarbonate and epinephrine, intubation and ventilation. Eight minutes after being pronounced dead, the patient had gasping respirations and spontaneous recovery of circulation and respirations. PaCO2 was 10 mm Hg during the resuscitation. It was hypothesized that the lag period was due to the time required for the medication to take effect and the cessation of high intra-pleural pressures from vigorous ventilatory support, allowing improved venous return to the heart and increased cardiac output. Ann. Emerg. Med. 25:4, 562. The development of a gasping respiratory effort has previously been noted as a sign preceding the Lazarus phenomenon. Lancet 341:841, 1993. This phenomenon may be seen in instances of dynamic hyperinflation during CPR when positive pressure ventilation results in auto-PEEP development and associated hypotension or pulseless electrical activity sometimes referred to as electromechanical dissociation. High intrathoracic pressures result in decreased venous return and increased aortic impedance and hypotension. This may occur in patients with chest trauma and pulmonary contusions, ARDS, or asthma. These patients may have return of pulse and blood pressure when resuscitation is discontinued and positive pressure in the thorax is decreased. JAMA 269:2128, 1993.
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