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Shots - Health Blog
Wed September 19, 2012
Tiny Bubbles: Injectable Oxygen Foam Tested For Emergency Care
A lot of medicine's direst emergencies come down to one problem: lack of oxygen.
Cardiologist John Kheir started thinking about that when a little girl in his care, drowning from lung hemorrhages, died before she could be hooked up to a heart-lung machine that would have kept her blood oxygenated while the damage was repaired.
That was in 2006. Now Kheir and his colleagues at Children's Hospital in Boston think they've figured out a way to inject oxygen directly into the bloodstream — a route that could save the lives of many patients who can't get enough oxygen, fast enough, through their airways.
Currently, injecting oxygen (or any gas) directly into the bloodstream is a big no-no, because it can form a large bubble called an embolism — an obstruction that can be fatal.
The new method — not yet tried in humans — encapsulates pure oxygen in microbubbles made of fat molecules. "It's a foam a lot like shaving cream," Kheir told Shots. "The purpose is to carry oxygen gas in an injectable way."
The bubbles release the oxygen in milliseconds in oxygen-starved tissues. That happens because of the natural affinity of hemoglobin, the business molecule within red blood cells, for oxygen. If there's any oxygen in the vicinity, hemoglobin immediately soaks it up.
Kheir says his injectable oxygen foam could buy crucial time in a number of medical scenarios, such as:
- On ambulances, when there's a need to deliver oxygen as fast as possible to a patient during cardiac arrest, an asthma attack, a near-drowning episode or other catastrophes.
- On the battlefield, when it can be difficult to insert a breathing tube into the airway of an injured soldier in hemorrhagic shock.
- In the intensive care unit, when conventional oxygen delivery through a mask is compromised by lung injury or disease, severe asthma, obesity or convoluted airways.
"This would help us stabilize patients for a few minutes, and that could be immensely valuable," Kheir says.
So far the injectable oxygen has been tested only in rabbits with experimentally blocked windpipes. The researchers have been able to keep rabbits alive for up to 15 minutes without a single breath. All but one of the animals that got the oxygen foam avoided the cardiac arrest that follows oxygen deprivation within 8 to 10 minutes.
The next step is to give the oxygen injections to healthy volunteers to test its safety. Then comes the difficult part — identifying those patients who could be given the oxygen foam during real-life instances of oxygen deprivation.
"That's a complicated question," Kheir says, "because we really want to have a patient population we can not only study effectively but who can consent ahead of time, and these are emergency situations."
The research has been funded up to now by a $1.5 million grant from the Department of Defense. The work is described in a paper published in Science Translational Medicine.