Researchers at the University of Pennsylvania School of Medicine have helped develop a technique in animal models for using the abdominal cavity to exchange gas, supplementing the function normally performed by the lungs.
The goal is to provide a way to support patients who are on a mechanical ventilator, suffering from reversible lung failure, but who need extra time and support to heal -- beyond what a ventilator can provide -- in order to survive. The findings are in the August 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," explains Joseph Friedberg, MD, Associate Professor of Surgery and principal investigator of this 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, SARS, trauma, 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."
The system these researchers developed involves recirculating a gas-carrying liquid through the abdomen to deliver oxygen. They 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 (the actual percentage of blood that's carrying oxygen) from 73% to 89%. Doctors generally aim to keep the oxygen saturation of patients in the 90% range. Friedberg adds, "If this experimental finding can be translated to a critical care setting, this could be a potentially life-saving increase in oxygenation."
Friedberg's idea was inspired by a similar technique, already used for patients suffering from kidney failure -- peritoneal dialysis -- 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. Friedberg wondered if it would be possible to use the lining of the abdominal cavity for gas exchange, like a "supplemental" lung, analogous to the way it is used like a "supplemental" kidney with peritoneal dialysis. To test this idea, it was clear that a nontoxic liquid capable of dissolving large volumes of gas would be needed. Friedberg felt perfluorocarbons were well suited for this purpose.