Despite major advances in treatment and survival, cystic fibrosis patients tend to live with a chronic, low-grade inflammation resulting from a chronic state of infection. The genetic mutation that disrupts the body's balance of salt and fluid thickens lung mucus, which traps inhaled bacteria and viruses that are normally cleared.
"They are in a low-grade stage of inflammation all the time," Harris said. Patient participants in the study, for example, had a higher rate of inflammation than healthy controls and the higher their concentrations of inflammatory drivers such as C-reactive protein, the lower their pulmonary function.
When the 15 patients, age 8-18, peddled a stationary bike as long and hard as they could, it was leg fatigue rather than lung limitations, which stopped them. "It's not their lungs that are limiting their exercise capacity," Harris said. "But what about non-pulmonary factors that we had no idea existed in these kids?"
"At this stage, their lungs are as healthy as those of their healthy counterparts," McKie added.
They found that even though the patients could take in oxygen well they were not as good as their 15 healthy counterparts at using it. At rest, oxygen saturation in the patients' blood was lower. During peak exercise, the amount of oxygen they consumed was 14 percent lower while expelled air had higher oxygen levels, indicating that their muscles were not as efficient at using it.
Another telltale sign was the fact that their blood vessels simply didn't dilate as well. The researchers put a cuff on the lower arm to increase blood flow through the brachial artery, a major vessel in the bicep. How much the artery dilates in response to the increased flow when the cuff is released depends on how much nitric oxide is available and it was significantly less in patients versus cont
|Contact: Toni Baker|
Georgia Health Sciences University