John Kheir, MD, a physician in the Cardiac Intensive Care Unit at Boston Children’s Hospital, led a team that created tiny particles filled with oxygen gas, which, when mixed with liquid, could be injected directly into the blood. In an emergency, IV oxygen delivery could potentially buy clinicians time to start life-saving therapies.
In 2012, the solution could completely saturate red blood cells in oxygen-deprived rabbits within seconds of injection, and they kept rabbits with totally blocked airways alive for 15 minutes using the oxygen-infused microparticles. “Essentially as soon as we started injecting it, clinically we started to see an effect,” Kheir told ScienceNOW.
Researchers are now testing the microparticle solution on large animals, and if those and later human clinical trials are successful.
The microparticle used to package oxygen gas, covered by a layer of fatty molecules and stabilizing agents. Upon contact with an oxygen-poor red blood cell, it releases oxygen, which rapidly binds to the cell. The lipid shell is metabolized by the body.
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Microparticles delivered by an IV catheter. (Images: Emily McIntosh)
ABSTRACT – We have developed an injectable foam suspension containing self-assembling, lipid-based microparticles encapsulating a core of pure oxygen gas for intravenous injection. Prototype suspensions were manufactured to contain between 50 and 90 ml of oxygen gas per deciliter of suspension. Particle size was polydisperse, with a mean particle diameter between 2 and 4 μm. When mixed with human blood ex vivo, oxygen transfer from 70 volume % microparticles was complete within 4 s. 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. The particles were also infused into rabbits undergoing 15 min of complete tracheal occlusion. Oxygen microparticles significantly decreased the degree of hypoxemia in these rabbits, and the incidence of cardiac arrest and organ injury was reduced compared to controls. The ability to administer oxygen and other gases directly to the bloodstream may represent a technique for short-term rescue of profoundly hypoxemic patients, to selectively augment oxygen delivery to at-risk organs, or for novel diagnostic techniques. Furthermore, the ability to titrate gas infusions rapidly may minimize oxygen-related toxicity.