Dr. Wolfgang Kuebler, a Li Ka Shing Knowledge Institute scientist at St. Michael’s Hospital, has found that in patients with lung edema – a common symptom of various diseases, such as acute heart disease, where the lungs fill with fluid – the lungs are actually pumping the wrong way, causing the lungs’ air spaces to fill with fluids. This groundbreaking research was published online on May 3 in Proceedings of the National Academy of Sciences of the United States of America, a high-impact journal and one of the world’s most-cited multidisciplinary scientific serials.
“Usually, our lungs pump fluid out of the air space, but in people who suffer from lung edema, the pump mechanism doesn’t work properly. It was previously believed that it just stopped,” said Dr. Kuebler. “We’ve found that not only have they stopped pumping fluid out, as they’re supposed to do, they’ve gotten confused and are actually pumping in the reverse direction, bringing fluid into the lungs.”
This finding has important implications for the treatment of lung edema. Stopping the pumping mechanism, although seemingly counterintuitive, is protective. For the first time, this explains why Lasix, a commonly prescribed drug, works in treating lung edema – it simply prevents the pumps from pumping fluid into the air spaces. Lasix was previously believed to work exclusively by targeting the kidneys.
“With this information, more effective drugs that target just the lungs, and not the kidneys, can now be developed,” says Dr. Kuebler. “This is important for those who suffer from high-altitude edema, for example. These people are dehydrated, so while Lasix would work on the lungs, it wouldn’t help with their overall fluid status.”
Dr. Kuebler points out that this mechanism of pumping fluid into the air spaces is reminiscent of what happens in the fetal lung. In the womb, the lung works to pump fluids in and only after the baby is born, does that pumping mechanism reverse itself to pump fluid out. “You can actually now interpret lung edema as a functional regression of the adult lung to a fetal stage,” he says.
This research was funded by a Boehringer Ingelheim MD fellowship and a Canadian Institutes of Health Research grant.
St. Michael’s Hospital.