We describe an out-of-hospital cardiac arrest without prior hypothermia in which the patient made a complete neurologic recovery after 96 minutes of sustained pulselessness caused by recurrent ventricular fibrillation (VF). To our knowledge, this report describes the longest duration of continuous cardiopulmonary resuscitation in a normothermic person experiencing an out-of-hospital cardiac arrest that resulted in a good clinical outcome.

These events unfolded on a cold day in January 2011 with an outside temperature of −4°C. The patient was moved out of the cold into a fire hall garage across the street from the site of arrest for continued resuscitation. While a Mayo Clinic medical transport helicopter and flight crew were en route, the first responders continued CPR and, during the next 24 minutes, 6 rectilinear biphasic waveform defibrillation shocks with escalating energy (120-200 J) were delivered at intervals separated by CPR. Four of the 6 shocks terminated VF transiently, with recurrence of VF from 11 to 420 seconds after each shock. At no time were the first responders able to palpate a pulse, despite the transient presence of an organized electrocardiographic rhythm after 4 of the shocks.

The flight crew arrived on the scene 34 minutes after receiving the 911 call. By this time, several other emergency medical services agencies from neighboring communities had arrived to assist, and thereafter chest compressions and ventilations were rotated among all the personnel. After a period of uninterrupted CPR, the flight crew attached their advanced life support (ALS) monitor-defibrillator (Zoll M Series CCT defibrillator). Ventricular fibrillation was observed; the trachea was intubated, ventilation provided by a bag-valve-tube device, intravenous access obtained, CPR continued, and the first defibrillation shock from the ALS defibrillator delivered. The ALS defibrillator also delivered rectilinear biphasic waveform shocks. An end-tidal carbon dioxide sensor (Respironics Novametrix, Wallingford, CT) was attached to the endotracheal tube and, throughout the remainder of the resuscitation, end-tidal carbon dioxide tension was continuously monitored. This measurement is an objective indicator of pulmonary and therefore systemic blood flow during CPR^1,2 and of the efficacy of chest compressions.³ It has been used to determine the likelihood of a successful resuscitation in an out-of-hospital cardiac arrest.^4,5

Throughout the following 41 minutes, 5 mg of epinephrine, 300 mg of amiodarone, 1 mg of atropine, and 200 mg of lidocaine were administered intravenously. Despite the long period of arrest and resuscitation, the dose of epinephrine was limited to 5 mg because of documentation of good perfusion pressure by end-tidal carbon dioxide measurements and because of concern that further doses of epinephrine might perpetuate the recurrence of VF. Five defibrillation shocks interspersed with CPR were administered, 3 of which transiently restored an organized but pulseless rhythm for up to a maximum of 40 seconds. Throughout resuscitation, end-tidal carbon dioxide tension was consistently in the 28- to 36-mm Hg range during VF. These levels were consistent with good chest compression–generated blood flow (Figure 2), justifying continuation of the resuscitation with the hope of a good outcome. Continued rotation of rescuers performing chest compression ensured avoidance of rescuer fatigue. During chest compressions after the third ALS shock, a pulseless wide QRS complex rhythm was restored. The fourth shock changed the amplitude of this rhythm, which then degenerated back into VF. After the fifth ALS shock, with VF still present, a decision was made to administer 300 mg of additional amiodarone, rather than the protocol-authorized 150 mg. Following continued CPR, the sixth shock was delivered. After this shock, the end-tidal carbon dioxide tension was 37 mm Hg, and an organized rhythm was present (Figure 3). Although a pulse could not yet be palpated, it was assumed that a spontaneous circulation had resumed, and CPR was discontinued. The time from collapse to restoration of a sustained spontaneous circulation using this end point was 96 minutes. After several minutes, with sustained end-tidal carbon dioxide tensions observed on the monitor screen, an organized electrocardiographic rhythm resumed, and carotid and femoral pulses were palpated.

With continued sustained spontaneous circulation, the patient was placed into the helicopter and transported to Saint Marys Hospital in Rochester, MN. The flight took approximately 20 minutes. From the time of collapse to restoration of pulses, a total of 12 defibrillation shocks were delivered: 6 from the first responder AED and 6 with the ALS defibrillator.

On admission of the patient to the emergency department, a 12-lead electrocardiogram showed a sinus tachycardia, a nonspecific intraventricular conduction block, and ventricular premature complexes (Figure 4). After additional amiodarone was administered in the emergency department (for an episode of nonsustained ventricular tachycardia) and the patient was stabilized, he was urgently transferred to the cardiac catheterization laboratory, where a 100% occlusion of the mid-left anterior descending coronary artery with thrombus was confirmed. Percutaneous transluminal coronary angioplasty, stent deployment, and thrombectomy were performed successfully (Figure 5). Multivessel coronary artery disease was present, with chronic right coronary artery and obtuse marginal artery occlusions. Because the patient was experiencing acute pulmonary edema and cardiogenic shock, an intra-aortic balloon pump was inserted, and he was returned to the coronary care unit. Mechanical ventilation, begun during helicopter transport, was continued. Transthoracic echocardiography revealed an estimated left ventricular ejection fraction of 30% to 35%. Therapeutic hypothermia was not used because of hemodynamic instability that required an intra-aortic balloon pump and inotropic support. During the next several days, hemodynamic factors stabilized, pulmonary edema resolved, and acute renal failure, treated with continuous venovenous hemodialysis, also resolved.

A previous case report described resuscitation of 107 minutes with patient survival. The patient had been submerged in cold water for the preceding 48 minutes, and body temperature was 26.2°C after retrieval from the cold water.⁶ The accidental hypothermia provided brain protection during the submersion and most likely contributed to the good outcome.

A retrospective study reviewed a 5-year experience with prolonged resuscitation efforts in the cardiac catheterization laboratory with use of a mechanical device to maintain chest compression.⁷ Of 38 patients, 11 survived to hospital discharge, with a mean treatment time with the mechanical compression device of 28.15 minutes (standard error of the mean, ±3.4 minutes; range, 1-90 minutes).