Neuromuscular disease or upper airway obstruction can present with breathlessness on exertion. Routine physiologic studies such as spirometry or maximum voluntary ventilation (MW) may provide clues to their presence but unfortunately often give similar results making it difficult to separate the contribution of these diseases. Cardiopulmonary exercise testing (CPET) has been used in the evaluation of patients with dyspnea, but most of these studies have been in patients with cardiac disease, chronic airflow obstruction (CAO), or pulmonary parenchymal disorders. There are few reports of exercise studies in patients with tracheal stenosis or in patients with neuromuscular disease. The following case demonstrates the utility of CPET in discerning the cause of dyspnea in a patient who suffered from both neuromuscular respiratory disease and upper airway obstruction following remote poliomyelitis.
A 50-year-old white woman presented with acute poliomyelitis at age 10 years. Severe bulbar symptoms developed and required tracheostomy and negative pressure mechanical ventilation for approximately 6 months. The patient recovered with no discernible peripheral muscle weakness. She did note mild, subjective abdominal muscle weakness. She remained quite active with no limitation until age 34 years when she noted mild shortness of breath with exertion. Pulmonary function studies supported a central airway obstruction (Table 1). An otolaryngologist confirmed normal vocal cords but a tracheal abnormality. Tracheogram demonstrated narrowing of the trachea within 4 cm of the carina with “dynamic narrowing of the trachea to less than 50 percent of the normal tracheal lumen” consistent with tracheomalacia. canadian neighborhood pharmacy
Six years later, the patient was noted to have “tracheal stenosis at the glottic chink” by bronchoscopy. However, she did well until 1 year prior to presentation when she again reported worsening dyspnea with exertion and was evaluated at the University of Michigan. She was a life-long nonsmoker and had no other medical problems or allergies. There was no history of major surgical procedures other than the prior tracheostomy. She complied with a regular exercise program (daily aerobic exercise, including walking) that was unchanged over the several weeks preceding this evaluation. She was receiving no medication at the time of the study. Review of systems identified no symptoms of sleep disturbance, daytime hypersomnolence, or morning headaches.
Table 1—Serial Pulmonary Function Tests in a Patient With a History of Poliomyelitis
|FVC, % predicted||92||79||81||90|
|FEV,, % predicted||99||92||89||88|
|TLC, % predicted||105|