An injection that delivers oxygen directly into the bloodstream for patients who cannot breathe has been invented by scientists at Boston Children's Hospital, according a report published in Science Translational Medicine. The authors explained that when patients suffer from an obstructed airway or acute lung failure, they urgently need oxygen to reach their blood, otherwise they have brain injury or suffer from cardiac arrest.
The researchers designed an injection filled with tiny, gas-filled microparticles that can be administered directly into the bloodstream, supplying it with much-needed oxygen.
The microparticles are made of a single layer of fatty molecules that surround a miniscule pocket of oxygen - they are placed in a liquid solution and injected into the patients.
John Kheir and team say that patients who are injected with this solution, may regain near-normal blood oxygen levels within seconds.
In animal experiments, the authors reported that they could beep the animals alive without breathing for 15 minutes, drastically reducing the incidence of organ injury and cardiac arrest (the heart stops completely).
The oxygen injection may buy the patient valuable timeJohn Kheir explained that the microparticle solutions are easy to carry around, and could conveniently be utilized to keep people who cannot breathe alive, giving emergency personnel more time to get patients to a safe place where more sophisticated life-saving procedures can be carried out.
"This is a short-term oxygen substitute - a way to safely inject oxygen gas to support patients during a critical few minutes," he says. "Eventually, this could be stored in syringes on every code cart in a hospital, ambulance or transport helicopter to help stabilize patients who are having difficulty breathing."
The authors say the microparticle solution injections could not be used for more than fifteen to thirty minutes, because they contain fluid that would overload the blood if used for any longer.
These are not blood substitutes, Kheir stressed. Blood substitutes carry oxygen, but are of limited use when the lungs are not working and cannot oxygenate them. These microparticles are specifically designed for people who cannot breathe.
After caring for a young girl who had severe pneumonia in 2006 and suffered severe brain injury because of extremely low blood-oxygen levels, Kheir starting looking into the idea of injectable oxygen.
The little girl died before the medical team could get her on a heart-lung machine.
"Some of the most convincing experiments were the early ones. We drew each other's blood, mixed it in a test tube with the microparticles, and watched blue blood turn immediately red, right before our eyes."
It was several years before the team managed to get the microparticles safe for injection. Kheir said "The effort was truly multidisciplinary. It took chemical engineers, particle scientists and medical doctors to get the mix just right."
They used a sonicator - a device which emits high-intensity sound waves to mix lipids and oxygen together. Oxygen gas gets trapped inside tiny particles, about two to four micrometers in size - too small to see with the naked eye. They found that a solution in which 70% of the volume consisted of oxygen was just right for human blood.
"One of the keys to the success of the project was the ability to administer a concentrated amount of oxygen gas in a small amount of liquid. The suspension carries three to four times the oxygen content of our own red blood cells."
In previous studies in the early 1900s, scientists attempted to oxygenate blood with intravenous oxygen, but they failed. Sometimes they caused fatal gas embolisms.
The authors said:
"We have engineered around this problem by packaging the gas into small, deformable particles. They dramatically increase the surface area for gas exchange and are able to squeeze through capillaries where free gas would get stuck."
Written by Christian Nordqvist