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Neurologically intact survival following prolonged cardiac arrest monitored with continuous capnography and subsequent treatment with therapeutic hypothermia.

To the Editor: Previously, we reported complete neurologic recovery following a prolonged cardiac arrest in which the resuscitation was guided by continuous capnography.1 Herein we report a similar incident in a man with a long period of pulselessness and eventual recovery in which both continuous capnography and subsequent therapeutic hypothermia were used. 
 
A 61-year-old man told his wife that he was “not feeling well,” proceeded to the bathroom in their residence, and collapsed. His wife confirmed that he was unresponsive and called 911 emergency services. With coaching from the dispatcher, she attempted cardiopulmonary resuscitation (CPR), but chest compressions were frequently interrupted by competing attempts to arouse her husband or communicate with the dispatcher. A sheriff’s deputy arrived 9.2 minutes after receipt of the 911 call and attached an automated external defibrillator (AED) (HeartStart FR2+, Philips Medical Systems, Seattle, WA). The AED algorithm determined that ventricular fibrillation (VF) was present but not of sufficient amplitude, frequency, and conduction properties to warrant a shock, and therefore the rescuer was directed to perform 2 minutes of CPR before the first shock (Figure). This type of VF represents a rhythm that has degenerated over time into a nonshockable state. Emergency medical technicians from the community volunteer Emergency Medical Services arrived and continued CPR. They inserted a Combitube airway (Nellcor, Pleasanton, CA) and ventilated the patient with 100% oxygen. During the next 28 minutes, 10 shocks were delivered by the AED for recurrent VF, with each shock momentarily converting the rhythm, after which VF resumed. Thereafter paramedics and a medical helicopter flight crew arrived. An advanced life-support monitor/defibrillator (Zoll M Series, Zoll Medical Corp, Chelmsford, MA) was attached, which confirmed VF, and a shock was delivered. As with the preceding AED shocks, VF was only momentarily terminated. An intraosseous infusion was begun, the trachea was intubated, and end-tidal carbon dioxide tension monitoring was initiated (Respironics Novametrix, Wallingford, CT). Except for a brief period during which the end-tidal carbon dioxide tension was in the range of 13 to 21 mm Hg, the measurement was in the 28 to 35 mm Hg range, consistent with good pulmonary blood flow. Epinephrine 1 mg was injected, and subsequently two 300-mg doses of amiodarone were administered because of continued recurrence of VF, requiring a total of 6 shocks with the paramedic defibrillator. During the brief moments when VF was terminated by a shock, a pulse was never palpable. Another 1-mg dose of epinephrine was administered. After the sixth of these shocks, 50 mEq of sodium bicarbonate was injected because of the long duration of the cardiac arrest. Epinephrine was used sparingly because of the presence of recurrent VF and because the end-tidal data indicated an apparently adequate perfusion pressure during most of the resuscitation.1 After the sixth paramedic shock, followed by a period of CPR, an organized rhythm was present on the monitor, and the end-tidal carbon dioxide tension was 37 to 43 mm Hg. The calculated time interval from collapse to restoration of a sustained spontaneous circulation was 63 minutes. Ice packs were applied (around the neck, in the axillae, and over the groins), an intravenous infusion was initiated by the flight crew, and iced 0.9% saline solution was administered during helicopter transport. During transport to the hospital, the patient maintained a spontaneous circulation. Therapeutic hypothermia using the Arctic Sun Temperature Management System (Medivance Inc, Louisville, CO) was initiated. This intervention has been shown to improve survival and neurologic outcome in patients who remain comatose after resuscitation from out-of-hospital cardiac arrest with VF as the presenting rhythm.2 A 12-lead electrocardiogram revealed ST-elevation myocardial infarction, and the patient was taken to the cardiac catheterization laboratory where coronary angiography confirmed the presence of coronary artery disease and an intracoronary thrombus in the left anterior descending coronary artery. He underwent successful percutaneous coronary intervention and stent placement. An intra-aortic balloon pump was inserted to maintain hemodynamic stability. 
 
 
 
Figure. 
 
Presenting rhythm. This is nonshockable ventricular fibrillation as described in the text. 
 
 
 
For editorial comment, see page 1038 
 
The postintervention period in the coronary care unit was accompanied by respiratory and renal failure, requiring prolonged mechanical ventilation and venovenous hemodialysis. The patient recovered from both of these insults and underwent a brief period of brain rehabilitation. One month after the event, he was discharged home with a cerebral performance category score of 1, representing a fully conscious state, alertness, and normal cerebral function except for a mild memory deficit. 
 
As we previously reported, resuscitation from a very prolonged cardiac arrest caused by recurrent VF can result in a favorable outcome with aggressive interventions. Guidance of resuscitation by continuous capnography provides an objective quantitative measure of the adequacy of chest compressions and the likelihood that a spontaneous circulation can be restored.3,4 Use of continuous capnography during resuscitation followed by therapeutic hypothermia in similar prolonged VF arrests may offer new opportunities for a favorable outcome, even when the arrest is very prolonged and seemingly intractable.