Oxygen-Filled Microparticles Could Save Lives When Breathing Is Impaired

Patients unable to breathe due to acute lung failure or an obstructed airway could be saved by tiny, gas-filled microparticles that can be injected directly into the bloodstream to oxygenate the blood quickly.

Researchers at Boston Children’s Hospital (MA, USA) developed the microparticles, which consist of a single layer of lipids that surround a tiny pocket of oxygen gas, and are delivered in a liquid solution. The microparticle solutions are portable and could stabilize patients in emergencies for a period of up to 15-30 minutes. Longer periods are riskier, because they are carried in fluid that would overload the blood if used excessively. The time span could help paramedics or intensive care unit (ICU) clinicians to more safely intubate patients or perform other life-saving therapies.

To manufacture the microparticles the researchers used a device called a sonicator, which uses high-intensity sound waves to mix the oxygen and lipids together. The process traps between 50 and 90 milliliter of oxygen gas per deciliter of suspension inside particles averaging 2-4 micrometers in size, which dramatically increase the surface area for gas exchange, and enables them to “squeeze through” capillaries where free gas would get stuck. The resulting solution, with oxygen gas making up 70% of the volume, allows the delivery of a concentrated suspension that carries three to four times the oxygen content of red blood cells (RBCs).

In in-vivo experiments, when the microparticles were infused by intravenous injection into hypoxemic rabbits, arterial saturations increased within seconds to near-normal levels; this was followed by a decrease in oxygen tensions after stopping the infusions. An infusion of the microparticles into rabbits with complete tracheal obstruction restored blood oxygen saturation to near-normal levels within seconds, keeping the animals alive without breathing for 15 minutes, thus drastically reducing the incidence of organ injury and cardiac arrest. The study was published in the June 27, 2012, issue of Science Translational Medicine.

“This is a short-term oxygen substitute, a way to safely inject oxygen gas to support patients during a critical few minutes,” said lead author John Kheir, MD, of the department of cardiology. “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.”

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Boston Children’s Hospital