An all too familiar and frustrating sight for doctors and nurses the world over, patients who suffer a cardiac arrest under their care due to trauma involving car accidents, gunshot or stab wounds rarely survive, with CPR techniques presenting less than a 5% survival rate in the hospital Emergency Room (ER).
To counteract these low survival rates, a suspended animation technique known as Emergency Preservation and Resuscitation (EPR) has been developed utilizing hypothermia in humans to buy vital time to stabilize the patient before irreversible organ damage occurs. Human trials, however, have been greatly complicated by the fact victims of trauma and cardiac arrest are incapacitated and therefore unable to personally consent.
Suspended animation in the ER
Now, a study from researchers at the University of Maryland places humans in suspended animation for the first time after gaining special exemption from the FDA for their trial. The team states by extending the time window for surgical management of vascular injury and other hemorrhagic pathology, EPR may allow patients to survive previously lethal bleeding. The interim results were presented by the lab at a symposium for the New York Academy of Sciences.
Recent studies in large animals from the group have demonstrated cooling to tympanic membrane temperature of 10°C during exsanguination cardiac arrest can allow up to 2 hours of circulatory arrest and repair of simulated injuries with normal neurologic recovery.
Moving this technique into human trials meant the FDA had to make the trial exempt from needing patient consent based on the criteria the participants’ injuries were likely to be fatal and there was no alternative treatment available.
The team was also legally required to have discussions with the local community, place ads in newspapers describing the trial, and direct people to a website where they could legally opt-out of the trial should they have a critical accident requiring CPR in an ER setting. The current study investigates the use of EPR on patients who have lost approximately 50% of their blood and had their chest opened previously during ER treatment, which will allow injection of the cooling solution directly into the heart.
The current study will involve 10 people who receive EPR and 10 people acting as controls who would have been eligible for the treatment had the EPR team been present at the time of admittance to the ER.
EPR involves rapidly cooling the person to around 10 to 15°C by replacing all of their blood with ice-cold saline to induce a suspended animated state. The patient’s brain activity almost completely stops when they are disconnected from the cooling system and their body, which would otherwise be classified as dead, is moved to the operating theatre.
Results show the lab was successful in giving a surgical team extra time to fix a participant’s injuries before they were warmed up and their heart restarted. The team state now they are placing people in suspended animation, they are learning a lot as they move forward with the trial.
Injuries are minimized using EPR
They go on to add it may be possible to give people a cocktail of drugs to help minimize injuries and extend the time in which they are suspended, however, they stress they haven’t identified all the causes of reperfusion injuries yet.
The team surmises they have successfully placed a person in suspended animation. For the future, the researchers state they hope to be ready to announce the full results of the trial by the end of 2020.
Source: New Scientist
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