Scientists develop method to inject oxygen directly into bloodstream, bypassing lungs

When the lungs fail—whether from COVID-19, acute injury, or the cascade of complications that follows severe illness—the body faces a brutal choice. Doctors can place a patient on a mechanical ventilator, forcing air into damaged lungs with the hope that time and medicine will allow healing. But ventilators themselves carry a cost: they can injure the very tissue they're meant to help, introduce infection, and they're never available in sufficient numbers when crisis strikes. A team of researchers has now demonstrated a method that sidesteps this dilemma entirely, delivering oxygen directly into the bloodstream without passing through the lungs at all.

The approach builds on existing technology called Extracorporeal Membrane Oxygenation, or ECMO, which has long been used in the most desperate cases. ECMO works by routing blood outside the body, oxygenating it there, and returning it—a process that saves lives but requires specialized equipment and expertise. The new technique accomplishes something similar without removing blood from the patient at all. Instead, researchers have engineered a way to inject oxygen-laden bubbles directly into the veins, where they dissolve and release their cargo into the bloodstream.

The engineering challenge was formidable. Oxygen bubbles injected into blood vessels would normally block blood flow or cause other damage. The researchers solved this by creating bubbles so small they're actually smaller than red blood cells themselves—small enough to pass through capillaries without obstruction. They achieved this by forcing an oxygen-laden liquid through a series of progressively smaller nozzles, creating micro-bubbles at the nanoscale. But size alone wasn't enough. The team coated each bubble in a lipid membrane, a fatty layer that prevents the bubbles from becoming toxic to the blood and stops them from sticking together and forming dangerous clots.

When the bubbles enter the bloodstream, the lipid coating dissolves and releases the oxygen. In laboratory tests using donated human blood, the technique raised oxygen saturation levels from 15 percent to over 95 percent in just minutes. When tested on live rats, the same process increased saturation from 20 percent to 50 percent. These results represent proof that the concept works, at least in controlled settings. The researchers emphasize that they can precisely control both the amount of oxygen delivered and the volume of fluid administered—critical parameters when treating patients whose bodies are already in crisis.

The potential applications are significant. Patients with refractory hypoxemia—a condition where the lungs simply cannot absorb enough oxygen, sometimes triggered by prolonged ventilator use itself—could benefit immediately. Rather than accepting the damage that comes with mechanical ventilation, doctors might use this technique to oxygenate the blood directly, buying time for the lungs to recover or for other treatments to take effect. The researchers suggest the device could also serve as a bridge therapy, preparing a patient's body for ventilator support or sustaining them until a machine becomes available during surges in critical illness.

What the technology cannot yet do is replace ventilators or ECMO entirely. The researchers are careful to frame this as a proof of concept, not a finished product. No human has received this treatment. The next phase involves testing on larger animals before any clinical trials begin. The balance required is delicate—too much oxygen delivered too quickly can cause its own harm, while too little defeats the purpose. Getting that calibration right in living systems more complex than rats will take time.

But the researchers see a path forward that doesn't require choosing between this new method and existing life support. They propose integrating the oxygen-injection device directly into ventilators themselves, allowing it to work alongside mechanical ventilation rather than replacing it. This integration into existing clinical workflows could mean the technology reaches patients faster, without requiring hospitals to adopt entirely new equipment or protocols. The work has been published in the Proceedings of the National Academy of Sciences, and the team is now preparing for the next phase of testing. For patients whose lungs have stopped working, this represents a genuinely new option—not a replacement for what exists, but an addition to the toolkit, one that might reduce the damage done in the fight to stay alive.