There are times when doctors in the emergency room need to deliver oxygen to a patient fast, but for some reason -- lung failure, blocked windpipe -- they can't do it by traditional methods.

Now researchers led by Boston Children's Hospital pediatrician John N. Kheir have concocted a new way to deliver the breath of life to patients with incapacitated lungs: a foam made up of tiny pockets of gas surrounded by a thin layer of fat, able to be injected directly into the bloodstream.

The researchers described how they were able to use the injectable oxygen to keep rabbits alive for 15 breathless minutes in a paper published Wednesday in the journal Science Translational Medicine.

Kheir said in a statement Wednesday that the microparticle solution could help stabilize patients in dire straits, buying critical seconds and minutes for doctors to put in a breathing tube while staving off heart attacks and brain injury.

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, Kheir says.

The microparticles can't be used for periods much longer than 15 to 30 minutes, Kheir cautioned, since the fluid they're suspended in would dilute the patient's blood if administered for too long.

Kheir started working on injectable oxygen in 2006 after one of his patients, a young girl suffering from pneumonia, died when she began bleeding into her lungs and his team couldn't get her into a heart-lung machine quick enough.

Some of the most convincing experiments were the early ones, Kheir says. 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.

Kheir and his colleagues soon hit upon a method for making oxygen microbubbles and described it in a 2010 paper in the journal Langmuir.

The microscopic oxygen bubbles are made using a sonicator, which mixes oxygen and fat particles together with high-intensity sound waves. Each bubble is about 2 to 4 micrometers -- 2 to 4 thousandths of a millimeter -- across.

That small size allows Kheir's team to succeed where previous attempts to intravenously administer oxygen have failed. Whereas large bubbles of air in the bloodstream can get stuck in tiny vessels and block the flow of blood, causing an embolism, the little bubbles in their flexible fat casings can squeeze through.

Kheir says he owes much to his team, which over the years had to test different versions of the microparticle mixture to find the most optimal one.

The effort was truly multidisciplinary, says Kheir. It took chemical engineers, particle scientists and medical doctors to get the mix just right.

SOURCE: Kheir et al. Oxygen Gas-Filled Microparticles Provide Intravenous Oxygen Delivery. Sci Transl Med 4: 140ra88, 27 June 2012.

Medicine