Anatomy, ventilation, and pulmonary function tests

Obstructive vs. restrictive pulmonary disease patterns

Pulmonary function test results are used to sort disease processes into two broad patterns:

• Obstructive pattern: airflow out of the lungs is limited, so FEV1 drops more than FVC and the FEV1/FVC ratio falls below 70%. RV and TLC are often increased from air trapping. Common causes include chronic obstructive pulmonary disease (COPD), asthma, and bronchiectasis.
  • During an acute asthma exacerbation the patient has wheezing, tachypnea, tachycardia and visible effort to breathe, and in severe cases a silent chest with no audible wheezing can signal impending respiratory failure.
  • Chronic asthma is controlled with medications that modulate the allergic and immune response, usually inhaled glucocorticoids, while a short-acting beta-2 agonist is the quick-relief (rescue) inhaler.
  • Vocal cord dysfunction is paradoxical closing of the vocal cords on inspiration, causing inspiratory stridor and throat tightness that is often mistaken for asthma.
• Restrictive pattern: lung expansion itself is limited, so TLC and vital capacity are reduced while the FEV1/FVC ratio stays normal or increases. Common causes include pulmonary fibrosis, chest wall or neuromuscular restriction, and atelectasis.

Example: interpreting a spirometry result

A patient’s spirometry shows an FEV1/FVC ratio of 62%, along with an increased RV. Which disease pattern does this suggest?

Answer: An obstructive pattern, such as COPD. The FEV1/FVC ratio is below 70%, and the increased RV reflects air trapping. The PTA notes the documented PFT results in the medical record and communicates relevant findings to the supervising PT, who considers them when establishing or modifying the plan of care; the medical diagnosis itself is made by the physician.

Other pulmonary findings

• Clubbing is a change in the tissue under and around the fingernails and toenails; lung cancer is its most common cause, and chronic lung infections (bronchiectasis, cystic fibrosis, lung abscess), interstitial lung disease, and conditions that lower blood oxygen, such as some congenital heart defects, can also cause it.
• In the early stages of pulmonary hypertension, a person may have shortness of breath only with exercise, and breathlessness becomes more frequent as the disease progresses.
• Tactile fremitus is increased over pulmonary consolidation, such as lobar pneumonia, and decreased in pleural effusion and pneumothorax; bronchial breath sounds are heard over areas of consolidation.
• With some pneumonias a patient coughs up greenish or yellow mucus, or even bloody mucus; in pulmonary edema the sputum is frothy and blood-tinged instead.

Pulmonary rehabilitation, postural drainage, and mucolytics

• Pulmonary rehabilitation is a supervised program of exercise training and education for people with lung disease such as COPD; oxygen level, blood pressure and heart rate are tracked during exercise.
• In postural drainage, the right middle lobe is drained with the patient in Trendelenburg position rotated a quarter turn to the left with the knees flexed, the lingula with the patient in Trendelenburg position rotated a quarter turn to the right with the knees flexed, and the lateral basal segment of a lower lobe with the patient lying on the opposite side, rotated a quarter turn toward prone, with the foot of the bed raised.
• Mucolytics such as N-acetylcysteine and dornase alfa break down the chemical bonds or DNA polymers that hold mucus together, whereas expectorants increase the water content of secretions.