Treatments for Victims of Cardiac Arrest
The HYPOTHERMIA study is being conducted under the U. S. Food and Drug Administration (FDA) “emergency waiver of consent” guidelines. This means subjects are enrolled in the study without their prior consent. Federal regulations usually do not allow patients to be enrolled in a study without their informed consent or without the consent of their next of kin. However, in certain limited situations, such as emergency medicine research, the U. S. Food and Drug Administration (FDA) does allow some studies to be conducted without prior consent. In order to be able to do a study using “waiver of consent” requirements established by the FDA must be met.
Cardiac arrest is a commonplace medical problem with major adverse health impacts. In the United States 225,000 people per year will die from cardiac arrest before reaching the hospital. Many more may never leave the hospital, or will do so severely disabled.
Following cardiac arrest, the brain is often injured due to a lack of blood and oxygen. Some patients will recover and wake up. However, a majority of patients resuscitated from cardiac arrest never awaken, despite the excellent care they receive. In other words, these patients never regain enough neurologic function to allow them to follow commands or to have comprehensible speech.
Effective treatments to protect the brain from the damage that accompanies cardiac arrest would allow more patients to awaken after cardiac arrest. To date, studies using various drugs have failed to improve neurological outcome after cardiac arrest. Researchers continue to look for new therapies that may improve the patient’s chance of awakening. Based on studies on patients who are admitted to the hospital following cardiac arrest, induced hypothermia (cooling the body) has been shown to improve the chances that a patient will wake up. In fact, in some hospitals, such as Harborview Medical Center, it is standard of care to cool these patients as soon as they are admitted to the hospital. Typically, patients who are unconscious following cardiac arrest are cooled to 33° 34° C (91.4°- 93.2° F) for 24 hours.
Animal studies have shown that the greatest benefits of cooling occur if it is started as soon as possible after the cardiac arrest.
Researchers at the University of Washington based at Harborview Medical Center are planning to conduct a large study of induced hypothermia in patients who have out of hospital cardiac arrest. It is thought that starting hypothermia outside the hospital may improve neurologic outcome and survival in this group of patients.
These same investigators recently completed a small pilot study of 125 subjects to test whether starting cold fluids in the field is safe and effective. The study showed that Seattle Fire Department paramedics could identify appropriate patients and begin the infusion of cold IV fluids in patients with out of hospital cardiac arrest. Patients arrived at the hospital with temperatures lower than those patients who did not receive any cold fluid. In this preliminary study there were no adverse effects. A study involving a larger number of subjects would allow more safety data to be obtained.
The purpose of the larger Hypothermia study is to test whether starting cooling, using cold IV fluids, as soon as possible before someone arrives at the hospital improves their condition and survival. This type of cooling is considered experimental. It is allowed by the United States Food and Drug Administration (FDA) in research studies only. This larger study will enroll 1000 subjects and will involved Seattle Fire Department and King County Emergency Services paramedics.
The potential risks involved in this trial include the following: discomfort or pain, too large of a temperature drop and fluid overload. There are safety measures built into the plan to minimize any of these risks. In the studies cited above there have not been any of these complications reported. However there may be unknown or unexpected risks.
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