“Rescue 1, delta response for a cardiac arrest at 911 Post Street, ‘The Gym.’ CPR in progress.”
On arrival, you find a 57-year-old male lying next to a treadmill. CPR is being performed by first responders, who state that when they arrived, bystanders were performing compressions-only CPR.
The first responders report they took over CPR at a rate of 30:2 using a bag-valve mask (BVM) and attached ResQPOD impedance threshold device (ITD). They applied their AED, which indicated a shockable rhythm, and the patient was defibrillated with 200 joules bi-phasic. They immediately resumed CPR without stopping to check for a post-shock pulse.
You and the first responders rotate a different crew member to perform chest compressions every two minutes while obtaining vascular access. The AED provides feedback prompts to encourage you to perform compressions at 100/min, and it also prompts you to push harder when the depth of compressions is too shallow.
After two minutes of CPR, you analyze the rhythm, and the AED indicates a shock is advised. You charge and deliver a second shock at 200 joules and immediately resume chest compressions. You insert a King LTS-D and attach the ITD to it. A waveform capnography reading of 25 indicates good perfusion with CPR.
Following two more minutes of CPR, you switch to your ALS monitor/defibrillator and, seeing that the underlying rhythm is V-fib, administer 40 units of vasopressin. You then defibrillate the patient with 200 joules and continue CPR for an additional two minutes.
The patient is now in a sinus tachycardia of 120 with a pulse and a BP of 80/40. You remove the ITD and induce hypothermia by administering two liters of chilled saline and sedating the patient with Versed.
In preparation for transport, you place the patient on a mechanical CPR device in the event CPR is needed during transport. You establish a second IV and prepare dopamine in case the patient’s BP drops further. However, at this time, you hold off administering it because pulse oxymetry is 98% and EtCO2 is 40, indicating good perfusion.
Just prior to transport, you perform a 12-lead ECG that shows ST elevation in leads II and III and a rhythm consistent with an inferior wall myocardial infarction.
Because the airway is secure and the patient is sufficiently stable for transport, you bypass the nearest hospital for one your medical director has designated as a cardiac arrest resuscitation center, and you activate a cardiac arrest alert.
On arrival, the stability of the patient is assessed, and a special cooling jacket is applied to continue induced hypothermia. From there, he’s taken directly to the cath lab, where he undergoes coronary angiography and has a stent placed in the right coronary artery. Additionally, an internal cardio-defibrillator is inserted. The patient is then taken to the ICU, where he’s kept in a pharmacologic coma, and therapeutic hypothermia is continued for 24 hours.
On day two of his hospitalization, your patient awakens with no memory of the event but exhibits no sign of neurological deficit. He’s discharged to home on day seven to begin cardiac rehab at the very same athletic club where he suffered his cardiac arrest.
The sad fact is that this sequence of events doesn’t reflect the typical out-of-hospital cardiac arrest in most EMS systems throughout the country today. We’ve made great strides in our understanding of the physiology of cardiac arrest, and the 2005 AHA guidelines provided us with several clear recommendations.1
The most notable points of the recommendations are the emphasis on quality CPR and the use of the ITD (Class I and Class IIa), which has more science to support its use than the drugs we administer (Class IIb or indeterminate).
Since these guidelines were released, a flurry of research has promoted one form of CPR over another. The largest of these was the multi-center Resuscitation Outcomes Consortium (ROC) Prehospital Resuscitation using an IMpedance valve and Early versus Delayed Defibrillation (PRIMED) study that was ended early when the researchers issued a National Institutes of Health press release Nov. 6, excerpted here:
“The Resuscitation Outcomes Consortium (ROC), the largest clinical research network to study prehospital treatments for cardiac arrest in the United States and Canada, tested both resuscitation strategies as part of the Prehospital Resuscitation using an IMpedance valve and Early versus Delayed (ROC PRIMED) clinical trial. An impedance valve, also called an impedance threshold device (ITD), is a small, hard plastic device about the size of a fist that is attached to the face mask or breathing tube during CPR administered by EMS providers. The device is designed to improve circulation by enhancing changes in pressures within the chest during CPR.
The study’s independent monitoring board and the National Heart, Lung, and Blood Institute (NHLBI), the lead sponsor of the study, stopped enrollment based on preliminary data suggesting that neither strategy significantly improved survival.”
Unfortunately, many took this to mean that nothing improves cardiac arrest survival. In actuality, every service that participated in the study had an increase in survival regardless of which arm of the study they were in. The real take-home message is that there’s no “silver bullet” for cardiac arrest resuscitation.
It’s like making the world’s greatest apple pie. You can’t simply throw all the ingredients into a bowl and expect a pie to spontaneously appear. The right ingredients must be placed together in the proper sequence to be successful. This applies equally to cardiac arrest resuscitation.
If bystander CPR isn’t performed, and it takes eight minutes to get to the patient, the outcome is dreadful. If bystander CPR is performed, and first responders take over but perform poor-quality CPR before you arrive, the outcome is the same.
The ITD isn’t a ventilatory device, despite the fact that it’s used in combination with the BVM. It’s a circulatory enhancer, and if the goal of quality CPR is to promote perfusion, it makes the most sense to utilize the ITD with the BVM rather than delay its application until after an advanced airway is established some four to eight minutes into the resuscitation.
If we transport a patient in cardiac arrest, the science shows that manual CPR provides less than 25% of the perfusion of stationary CPR. Mechanical CPR devices can do what the human can’t—maintain reliable performance of a repetitive and tiring motor skill. The rate of return of spontaneous circulation (ROSC) following transportation of a patient in cardiac arrest with manual CPR en route is no better than those who didn’t receive bystander CPR.
For too long our patients have died in the hospital despite our delivering them to the emergency department with a pulse. The data supporting the use of induced hypothermia and early cardiac catheterization strongly favor the designation of cardiac arrest resuscitation centers that utilize them.
Only when we approach cardiac arrest resuscitation with a systemwide deployment of all the ingredients that we believe improve survival will we see a significant improvement in survival (see Table 1, JEMS August issue, pg. 38).
Leading by Example
Many initiatives have shown the benefit of such an approach. The most notable is the Wake County (N.C.) experience.2 The value of treating cardiac arrest with the same type of systemwide approach we do for trauma is also highlighted by the success of Arizona and its designation of resuscitation centers.3 In fact, the ROC PRIMED study found a wide variation in pre-study survival by each of the participating systems, from a low of 5% to high of 28%, which would indicate significant differences in their system’s approach to cardiac arrest resuscitation.4
Take Heart America is a program that provides the tools to develop a true systemwide approach and has a proven track record of success.5
I’m looking forward to the 2010 AHA guidelines; I suspect they’ll further emphasize the need for a systemwide approach, so we can quit wasting our time searching for the silver bullet and instead get serious about putting all the ingredients together for successful patient care. JEMS
This article originally appeared in July JEMS as “No Silver Bullet: Cardiac arrest survival depends on numerous strategies.”