Relationship Between PFTs and Pdi in DMD

The Relationship Between Pulmonary Function Measures and Transdiaphragmatic Measures in Duchenne Muscular Dystrophy Subjects

A cross-sectional study to explore the relationship between clinically assessed pulmonary function test (PFT) measures and transdiaphragmatic (Pdi) measures in Duchenne muscular dystrophy (DMD) as well as to explore the relationship between sniff nasal inspiratory pressure (SNIP) and transdiaphragmatic (Pdi) measures in Duchenne muscular dystrophy.

Two small balloons, which are attached to small, flexible tubes, will be put into the esophagus and stomach through your nose. Each balloon is about 2 inches long (deflated) and about the width of a pencil tip. To reduce any discomfort with this procedure, lidocaine gel or spray will be put into the subject's nose and administered to the back of the throat before the balloon. In addition, swallowing water during the procedure will help to reduce any gagging sensation and will assure that the balloon goes into the esophagus. Proper placement of the catheters will be determined using normal tidal breathing against an occluded mouthpiece with a nose clip. Once proper placement is ensured, the catheters will remain in place during your normal PFT maneuvers. Additionally, while the gastric and esophageal balloon catheters are in place, the subject will be asked to perform a maximal sniff maneuver (SNIP) while one nostril is occluded with a plug containing a distal pressure measurement catheter to measure airway pressure. The distal end of the pressure catheter will be connected to a hand held pressure meter to display peak pressure and to provide you visual feedback. This maneuver will be performed 10 times.

Two small balloons, which are attached to small, flexible tubes, will be put into the esophagus (food tube) and stomach through the nose. Each balloon is about 2 inches long (deflated) and about the width of a pencil tip. A gastric balloon will be inserted into subject's stomach while an esophageal balloon will be inserted into the subject's esophagus. To reduce any discomfort with this procedure, lidocaine gel or spray will be put into the subject's nose and administered to the back of the throat before the balloon. In addition, swallowing water during the procedure will help to reduce any gagging sensation and will assure that the balloon goes into the esophagus.

While the gastric and esophageal balloon catheters are in place, the subject will be asked to perform a maximal sniff maneuver (SNIP) while one nostril is occluded with a plug containing a nasal pressure transducer to measure airway pressure during maximal inspiration. The distal end of the pressure catheter will be connected to a hand held pressure meter to display peak pressure and to provide you visual feedback. This maneuver will be performed 10 times.

Small flexible catheter with deflated balloon at distal end to be inserted into the esophagus through the nose

Small flexible catheter with deflated balloon at distal end to be inserted into the stomach through the nose

For all subjects Pdi (transdiaphragmatic pressure measures) will be assessed with gastric and esophageal balloons

For all subjects, SNIP (sniff nasal inspiratory pressures) will be assessed with a nasal pressure transducer

For all subjects, FEF25-75 (the average forced expiratory flow during the mid (25 - 75%) portion of the FVC) will be assessed with spirometry

Inclusion Criteria: Clinical diagnosis of Duchenne muscular dystrophy Exclusion Criteria: Inability to follow verbal instructions