Vol. 19 • Issue 18 • Page 10
Patients with moderate to severe chronic obstructive pulmonary disease (COPD) exhibit a disordered breathing-swallowing pattern that may account for their higher risk of aspiration pneumonia, according to new research from the University of Pittsburgh.1
Patients with moderate to severe COPD exhibit alterations between breathing and swallowing patterns even when they are not experiencing exacerbations, reported Roxann Diez Gross, PhD, CCC-SLP, director of the UPMC Swallowing Disorders Center, Eye & Ear Institute, in Pittsburgh, PA.
While patients with COPD were known to exhibit decoupling of the breathing-swallowing pattern of saliva during exacerbations, there had been no formal studies detailing to what extent these disruptions in breathing and swallowing coordination occurred in this population outside of exacerbations during normal eating.
Dr. Gross and her colleagues examined the relationship between swallowing and timing of breathing in 25 patients with moderate to severe COPD and compared them with 25 healthy subjects. Each subject consumed nine wafer cookies and 10 teaspoons of pudding to determine any differences in the handling of solid versus semi-solid food. A pattern emerged in patients with COPD that was strikingly different from that of the healthy controls.
"In healthy subjects the usual pattern is to time swallows to occur during early to mid-exhalation," said Dr. Gross. "Healthy individuals also nearly exclusively follow each swallow with exhalation. This pattern assures that there is sufficient air pressure below the vocal folds during a swallow and prevents inhalation of food residue after swallowing."
In contrast, she said, "We saw that several aspects of the swallowing and breathing timing in COPD patients were disrupted such that swallows were occurring during inhalation or were followed by inhalation. COPD patients also swallowed more often at the end of exhalation at lower lung volumes."
The complicated physiology of the upper respiratory tract may be thrown out of balance by the respiratory burden imposed by COPD, Dr. Gross explained. "Because breathing and eating share the structures of the upper airway, precise coordination is needed to prevent food material from entering the airway while eating. In patients with COPD, the competition for the upper airway may cause the respiratory drive to override swallowing function and disrupt the normal patterning. The lungs of COPD patients have less elasticity than those of healthy individuals, and this may also play a role in
Difficulty swallowing, often related to weakness, is associated with many neurological diseases, such as Parkinson's disease. The observed impaired breathing and swallowing patterns in patients with COPD suggest a possible explanation for the presence of swallowing disorders in people who do not have neurological illness.
These findings have immediate clinical implications, Dr. Gross noted. "Unrecognized aspiration can occur prior to or during COPD exacerbation and may contribute to the onset and severity of the exacerbations. Patients with COPD should have their swallowing function evaluated during hospitalizations, and aspiration should be suspected when exacerbations cannot be linked to viral infections or other factors."
Further research is being conducted that examines the interactions between control of the respiratory cycle, lung elasticity and swallowing function. Currently, therapies that manipulate the respiratory system are being developed to improve swallowing function and safety.
1. Gross, R.D., Atwood, C.W., Ross, S.B., et al. (2009). The coordination of breathing and swallowing in chronic obstructive pulmonary disease. American Journal of Respiratory and Critical Care Medicine, 179 (7): 559-65.