Technique Helps Sick Lungs Deliver Oxygen

A new technique has been developed in animal models for using the abdominal cavity to exchange gases, supplementing the function normally performed by the lungs.

Researchers at the University of Pennsylvania School of Medicine (Philadelphia, USA) developed the technique, which involves recirculating inert perfluorocarbons--a class of compounds developed during the Manhattan Project that have an extraordinary gas-dissolving capacity--through the abdomen to deliver oxygen.

The researchers tested the system in adult pigs that were put to sleep and ventilated with low concentrations of oxygen to simulate lung failure. Using this technique, they observed an increase in arterial oxygen saturation--preferably in the 90% range--from 73% to 89%. The idea was inspired by peritoneal dialysis, a similar technique already used for patients suffering from kidney failure, in which a catheter is placed into the abdominal cavity and the blood is cleansed by using the lining of the abdominal cavity to exchange toxins and electrolytes. The research findings were published in the August 2006 issue of Chest, the journal of the American College of Chest Physicians.

"This is an alternate, novel way to deliver oxygen to the body that does not attempt to wring more function out of an already injured lung, by using ventilator settings that can actually exacerbate the underlying lung injury. The only other alternates that can ‘rest' the lung involve variations of bypass machine technology, all of which require anticoagulation,” said Joseph Friedberg, M.D., associate professor of surgery and principal investigator of the study. "The ability to rest the lungs and provide supplemental oxygen with a technique that appears nontoxic and does not require anticoagulants could have huge implications some day for patients suffering from potentially reversible pulmonary failure from such diseases as anthrax, bird flu, severe acute respiratory syndrome [SARS], trauma, acute respiratory distress syndrome [ARDS], pulmonary embolism, pneumonia, and others. Sometimes patients have a condition in which they might have a chance to recover if they could survive the most severe phase of their disease.”

An underlying problem of ventilation is ventilator-induced lung injury (VILI), a vicious cycle where the high vent settings required to support a patient with lung failure actually exacerbate the underlying lung disease, requiring even more vent support. A technique like abdominal perfusion, if proven to be safe and effective, could be used to short-circuit this positive feedback loop and "rest” the lungs instead of having them go into a potentially fatal spiral.



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