Frequently Asked Questions (Page 3)

ROC PRIMED Questions and Answers

What is an ITD?

An impedance threshold device is a small, hard plastic device about the size of a fist that is attached to the face mask or breathing tube during CPR by EMS providers. The ITD has been shown to increase blood flow and thus potentially improve CPR, which provides only about a quarter of normal blood flow when performed using standard methods. While the impedance device goes over the patient's mouth, it is not a breathing aid. Instead, the device increases the normal pressures created when the chest decompresses to improve blood flow to vital organs. In animal and smaller human research studies, the device has been shown to markedly increase blood flow during CPR and raise blood pressure. Human studies showed a tendency toward improved short-term outcomes without adverse effects. However, a large human study, such as ROC PRIMED, was needed to show whether the device significantly improves survival without neurological damage. A modified version of the ITD is approved by the U.S. Food and Drug Administration (FDA) for use in low blood flow conditions other than cardiac arrest.

What have other studies of ITD shown?

Smaller published studies in humans suggested that the ITD improves blood circulation and short-term outcomes, such as increased blood pressure. However the total number of patients enrolled was small. Although there was some evidence in these earlier studies favoring use of an ITD, the lack of demonstrated benefit in survival convinced the NHLBI and the ROC investigators that a larger randomized trial was needed to test whether an active ITD is better than a non-functional ITD.

What have other studies of Analyze Late versus Analyze Early shown?

Smaller published studies in humans suggested that CPR before defibrillation may increase survival but the results to date were inconclusive. Although there was some evidence in these earlier studies favoring immediate defibrillation (30 to 90 seconds) in cases where the response time is less than two minutes, such response times are rare and the frequent delay in recognition of the out-of-hospital cardiac arrest and calling 911, as well as the complexity of the resuscitation protocol, convinced the ROC investigators that a randomized trial was necessary to test whether Analyze Later is better than Analyze Early.

How did patients indicate they would participate in this study?

In most cases, the participant or their representative could not provide informed consent prior to treatment, as is done in most clinical trials. Because of the nature of the research, participants will either be in a semi-conscious or unconscious state when they are enrolled in ROC studies. Life-supporting interventions must be given immediately in the field to save their life. Patients are too sick to consent to immediate treatment. Surviving patients and/or their authorized representatives are informed about the trial as soon as feasible after the intervention has been given. Instead, the ROC research studies were conducted under federal regulations that allow an exception from explicit informed consent.

Before any patients were enrolled, communities were consulted about participation and made aware that informed consent will not be obtained for most study participants, as required by law. ROC PRIMED also includes follow-up telephone calls with survivors who are required to provide consent for this part of the study.

What is an exception from informed consent?

In 1996, the FDA developed specific regulations to permit research without prospective consent under carefully controlled circumstances. This is in recognition of the unique nature of emergency medical situations in which patients or family members cannot give informed consent before treatment as well as the need to allow emergency care to advance through research. According to FDA regulations, to qualify for an exception from informed consent, the research study must involve participants suffering from a life-threatening disease process or injury for which the current standard of care is associated with a very high failure or mortality rate. In addition, there must be reasonable evidence that the research has the potential to provide real and direct benefit to the patient. Furthermore, studies must be held to the highest ethical standards. The ROC trials have undergone multiple independent rigorous reviews to ensure that they meet these standards.

The use of a randomized clinical trial is the "gold standard" for determining what works best for people. For treatments that must be given immediately to be effective, exception from informed consent research is considered appropriate by federal regulatory bodies and many ethicists who study this field. The obligation to improve standard treatments that yield poor results in life-threatening conditions is also considered an ethical imperative, as is maintaining individual rights of citizens. In waiver of consent trials, citizens receive standard treatment in addition to research treatment. To be tested in this fashion, the research treatment has to have shown promise in earlier or smaller studies.

Would you let a family member be enrolled in a future study like this?

Yes, absolutely. Randomized trials are the best way for us to learn how to treat patients with acute life-threatening conditions like cardiac arrest. It is critical that we understand how to effectively treat patients with out-of-hospital cardiac arrest as it remains a significant and serious public health issue.

Should public bystanders be performing full CPR, with breathing and chest compressions, or using the "Hands Only" method that was introduced last year?

The ROC PRIMED study did not explore this issue, however, the American Heart Association (AHA) in 2008 put out a science advisory to encourage the general public to skip the ventilation step in CPR and focus only on continuous chest compressions and having someone call 911. Chest compressions should be delivered until professional assistance arrives. The AHA last issued revised guidelines in 2005. In the 2005 version, it was recommended that trained emergency medical service providers use a combination of ventilation and chest compressions, with a greater emphasis placed on chest compressions. The next AHA guidelines are scheduled to come out in October 2010.

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More information:

Study Results

Results were published in the New England Journal of Medicine on September 1, 2011.

Cardiac Arrest and the Limitations of Clinical Trials
Read the Editorial

A Trial of an Impedance Threshold Device in Out-of-Hospital Cardiac Arrest
Read the Article

Early versus Later Rhythm Analysis in Patients with Out-of-Hospital Cardiac Arrest
Read the Article