San Diego—Patients with inflammatory bowel disease (IBD) may experience a flare of IBD-related symptoms when they travel by air, according to new findings reported here at the annual Digestive Disease Week conference.
Airplane cabins are pressurized to maintain an atmospheric pressure of about 2400 m (8000 ft), with an oxygen pressure that is 25% less than sea level. As a result, air passengers are exposed to hypoxic conditions that could exacerbate certain clinical conditions.
After Stephan Vavricka, PhD, chief of the division of gastroenterology and hepatology, Trieml Hospital in Zurich, Switzerland, and colleagues noted that some IBD patients who had traveled by air seemed to have flares of their disease, the group reviewed a cohort of 103 patients with known IBD and asked them about recent air travel or exposure to high-altitude environments. Of these 103 patients, 52 had recent flares of their disease, 21 of whom (40%) had such environmental exposures within 4 weeks of the flare. Of those with no recent disease flares, only 8 of 51 (16%) had been exposed to high altitudes or flights within 4 weeks of their flare.
A worsening of chronic inflammatory conditions related to air travel is biologically plausible. The body has sensitive mechanisms to detect and react to hypoxia, and when it detects low oxygen levels, activation of transcription factor 1-α up-regulates several gene systems. These include systems that generate energy by glycolysis and others that respond to vascular endothelial growth factor by inducing the formation of blood vessels. Humans exposed to high-altitude, hypoxic conditions have elevated blood levels of the inflammatory mediator molecules IL-6 and C-reactive protein, consistent with activation of inflammatory pathways.
Several physicians in the audience acknowledged similar observations of a possible link between air travel and IBD flares in patients with the condition. Alternative hypotheses for this potential relationship include changes in diet related to the travel destinations, bloating above obstructed bowel in patients with Crohn disease who have chronic obstruction, and the stress of long flights.
Larger, prospective studies are needed to confirm a potential association between IBD flares and flying. Nevertheless, given the plausible physiological evidence for the potential association, the researchers said, clinicians should consider obtaining a careful travel history from patients with IBD flares.