Approximately 400,000 people in the United States suffer out-of-hospital cardiac arrest (OHCA) each year. One-third present to EMS with a shockable rhythm (v fib/v tach). Of these patients with an initial shockable rhythm, 50% are refractory to treatment resulting in prolonged duration of resuscitation and poor outcomes.1,2
The Minnesota Resuscitation Consortium (MRC) initiated the Advanced Perfusion and Reperfusion Cardiac Life Support Strategy for Out-of-Hospital Refractory Ventricular Fibrillation (v fib) in December 2015, in an effort to improve survival outcomes for patients suffering refractory v fib arrest.
Extracorporeal life support (ECLS) provides two critical advantages to the care of patients with refractory cardiac arrest. First, it provides near complete replacement of cardiac function with flows of 4—5 L/min.
Second, the hemodynamic stability it provides enables the underlying causes of arrest to be addressed. Importantly, the primary etiology of refractory v fib is coronary artery disease, with 84% of refractory v fib patients presenting with severe coronary lesions. Further, these coronary lesions are highly complex with high syntax scores and a high rate of chronic total occlusions.3,4
Three Key Components
The MRC ECPR program has three key components: prehospital, stabilization and recovery. First, the prehospital care is highly coordinated and the paramedics involved have been highly trained to provide rapid assessment on scene and rapid transport, in the case of refractory cardiac arrest, to the cardiac catheterization laboratory (CCL) at the University of Minnesota for initiation of ECLS. Transport is performed with mechanical CPR and ITD and ongoing ACLS.
Patients are screened by paramedics using the following field criteria. Inclusion criteria include the following: 1) age 18—75; 2) OHCA of presumed cardiac etiology; 3) initial cardiac arrest rhythm of v fib, v tach; 4) received three defibrillation shocks without return of spontaneous circulation; 5) received IV amiodarone 300 mg; 6) body habitus accommodating a LUCAS automated CPR device; and 7) estimated transfer time to the CCL of < 30 minutes. Exclusion criteria include: DNR/DNI, live in a nursing home, or have a clear non-cardiac etiology to the arrest.
Second, the stabilization stage begins upon arrival in the CCL, with immediate assessment of the patient for resuscitation termination criteria including: 1) end-tidal carbon dioxide < 10 mmHg; 2) PaO2 < 50 mmHg; and 3) lactic acid < 18 mmol/L.
If none of these criteria are met, resuscitation continues with placement of ECLS within 6—8 minutes of arrival in the CCL.5,6 Ultrasound-guided percutaneous access is used for cannulation. Medical therapy is then provided to achieve hemodynamic stability.
Once hemodynamically stable, coronary angiography and PCI are performed as needed. Pulmonary angiography or laboratory testing may be performed as well. A distal perfusion cannula, IV cooling catheter, and right radial arterial line are placed, and LV venting is considered.
As the patient is transferred to the cardiovascular ICU, a CT scan of the head, chest, abdomen and pelvis is performed to evaluate for trauma. Traumatic injuries are then addressed as needed. Importantly, all patients are considered viable and all procedures are considered if needed until a patient is declared dead.
The last stage is recovery in the cardiovascular ICU, cardiac telemetry floor, and after discharge. Recovery is limited by severe multisystem organ failure, which is ubiquitous in this patient population. Although most organ systems will recover, including the heart, neurologic recovery limits survival in most patients. Recovery is delayed in most patients with mean time to ECMO decannulation of four days, following commands at six days, and hospital discharge at 21 days.
Importantly, prognostication efforts must be delayed, as patients who have neither followed commands nor been declared dead have a 35% chance of surviving at one week and 20% chance of surviving at two weeks post-arrest.
Anoxic brain injury or brain edema on CT scan at the time of cardiovascular ICU admission, decreasing near-infrared spectroscopy over the first 48 hours, severely elevated neuron-specific enolase, and nonconvulsive status epilepticus on EEG are associated with poor outcomes, but no single test can be used to determine prognosis.
Using these selection criteria and protocols, a 43% rate of neurologically intact survival can be achieved. This is compared to a 5% rate of survival for this population prior to initiation of this protocol.6
Importantly, post-discharge care is also critical for complete rehabilitation of this patient population. Psychological consequences including post-traumatic stress disorder, anxiety and depression are common.
Short-term memory deficits and personality changes are common immediately following the hospital stay. These deficits typically resolve with appropriate therapy. Patients are encouraged to seek physical therapy, psychological therapy, neuropsychologist evaluation and genetic counseling if a clear etiology of the cardiac arrest isn’t discovered. Follow-up cardiology care is also provided.
Overall, care for this patient population is highly specialized and time intensive. However, with these protocols, neurologically favorable survival can be improved substantially.
1. Stiell IG, Nichol G, Leroux BG, et al. Early versus later rhythm analysis in patients with out-of-hospital cardiac arrest. N Engl J Med. 2011;365(9):787—797.
2. Cheskes S, Schmicker RH, Rea T, et al. Chest compression fraction: A time dependent variable of survival in shockable out-of-hospital cardiac arrest. Resuscitation. 2015;97:129—135.
3. Yannopoulos D, Bartos JA, Raveendran G, et al. Coronary artery disease in patients with out-of-hospital refractory ventricular fibrillation cardiac arrest. J Am Coll Cardiol. 2017;70(9):1109—1117.
4. Lamhaut L, Tea V, Raphalen JH, et al. Coronary lesions in refractory out of hospital cardiac arrest (OHCA) treated by extra corporeal pulmonary resuscitation (ECPR). Resuscitation. 2018;126:154—159.
5. Yannopoulos D, Bartos JA, Martin C, et al. Minnesota Resuscitation Consortium’s advanced perfusion and reperfusion cardiac life support strategy for out-of-hospital refractory ventricular fibrillation. J Am Heart Assoc. 2016;5(6).
6. Bartos JA, Carlson K, Carlson C, et al. Surviving refractory out-of-hospital ventricular fibrillation cardiac arrest: Critical care and extracorporeal membrane oxygenation management. Resuscitation. 2018;132:47-55.