Flow-Volume Loop

• Variable Extrathoracic Upper Airway Obstruction: adversely affects predominantly inspiratory flow (as inspiratory negative intraluminal pressures exacerbate the inspiratory airway narrowing, while expiratory positive intraluminal pressures splints the obstruction open)
  • Example: vocal cord paralysis -> inspiratory stridor with no expiratory obstruction
• Variable Intrathoracic Upper Airway Obstruction: adversely affects predominantly expiratory flow (as inspiratory negative pressures decrease the inspiratory airway narrowing, while expiratory positive intrapleural pressures exacerbate the airway obstruction)
  • Example: tracheomalacia -> expiratory worsening of airway obstruction
• Fixed Upper Airway Obstruction: adversely affects both inspiratory and expiratory flows

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Spirometry

• xxx

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Lung Volumes

• xxx

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Diffusion Capacity for Carbon Monoxide (DLCO)

Increased DLCO

Etiology

• Diffuse Alveolar Hemorrhage (DAH) (see Diffuse Alveolar Hemorrhage, [[Diffuse Alveolar Hemorrhage]])
• Asthma (see Asthma, [[Asthma]]): due to increased pulm capillary blood volume

Decreased DLCO

Etiology

• Obstructive Lung Diseases (see Obstructive Lung Disease, [[Obstructive Lung Disease]])
  • Chronic Obstructive Pulmonary Disease (COPD) (see Chronic Obstructive Pulmonary Disease, [[Chronic Obstructive Pulmonary Disease]])
• Restrictive Lung Diseases
  • Interstitial Lung Disease (ILD) (see Interstitial Lung Disease, [[Interstitial Lung Disease]])
• Pulmonary Vascular Disease
  • Chronic Thromboembolic Pulmonary Hypertension (CTEPH) (see Chronic Thromboembolic Pulmonary Hypertension, [[Chronic Thromboembolic Pulmonary Hypertension]])
  • Idiopathic Pulmonary Arterial Hypertension (IPAH) (see Idiopathic Pulmonary Arterial Hypertension, [[Idiopathic Pulmonary Arterial Hypertension]])
• Other
  • Anemia (see Anemia, [[Anemia]])

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Restriction

Etiology -> P-A-I-N-T-O-P-P-M

Pleural Disease

• Examples
  • Fibrothorax (see Fibrothorax, [[Fibrothorax]])
  • Large Pleural Effusion (see Pleural Effusion-Exudate, [[Pleural Effusion-Exudate]])
• PFT Features
  • Variable lung volumes

Alveolar Filling Process

• Examples
  • Cardiogenic Pulmonary Edema (CHF) (see Congestive Heart Failure, [[Congestive Heart Failure]])
  • Pulmonary Alveolar Proteinosis (PAP) (see Pulmonary Alveolar Proteinosis, [[Pulmonary Alveolar Proteinosis]])
• PFT Features
  • Proportional decrease in TLC, FRC, RV, and VC

Interstitial Lung Disease (ILD)

• Examples
  • Idiopathic Pulmonary Fibrosis (IPF) (see Idiopathic Pulmonary Fibrosis, [[Idiopathic Pulmonary Fibrosis]])
  • Hypersensitivity Pneumonitis (HP) see Hypersensitivity Pneumonitis, [[Hypersensitivity Pneumonitis]])
• PFT Features
  • Decreased TLC
  • Decreased FRC
  • Decreased VC
  • Small decrease in RV

Neuromuscular Disease

• Examples
  • Amyotrophic Lateral Sclerosis (ALS) (see Amyotrophic Lateral Sclerosis, [[Amyotrophic Lateral Sclerosis]])
  • Bilateral Diaphragmatic Paralysis (see Bilateral Diaphragmatic Paralysis, [[Bilateral Diaphragmatic Paralysis]])
  • Guillain-Barre Syndrome (GBS) (see Guillain-Barre Syndrome, [[Guillain-Barre Syndrome]])
  • Muscular Dystrophy
  • Myasthenia Gravis (see Myasthenia Gravis, [[Myasthenia Gravis]])
  • Poliomyelitis (see Poliomyelitis, [[Poliomyelitis]])
• PFT Features
  • Decreased TLC in pure inspiratory weakness, but not in pure expiratory muscle weakness (this is one of the cases where restriction can be diagnosed in setting of a normal TLC)
  • No change in FRC in cases with both inspiratory and expiratory muscle weakness

Thoracic Cage Abnormality

• Examples
  • Ankylosing Spondylitis (see Ankylosing Spondylitis, [[Ankylosing Spondylitis]]): due to costovertebral spondylosis
  • Ascites (see Ascites, [[Ascites]])
  • Kyphoscoliosis (see Kyphoscoliosis, [[Kyphoscoliosis]])
  • Polydermatomyositis (see Polydermatomyositis, [[Polydermatomyositis]]): extensive soft tissue chest wall calcification
  • Pregnancy (see Pregnancy, [[Pregnancy]])
  • Scleroderma (see Scleroderma, [[Scleroderma]]): skin tightness over chest may restrict thoracic cage expansion
• PFT Features
  • Decreased TLC
  • Decrease in VC
  • Small decrease in FRC (normal-slightly increased in Ankylosing Spondylitis cases with restricted thoracic cage expansion)

Obesity

• PFT Features
  • xxxx

Pulmonary Hypertension

• Associated Disorders
  • Chronic Thromboembolic Pulmonary Hypertension (CTEPH) (see Chronic Thromboembolic Pulmonary Hypertension, [[Chronic Thromboembolic Pulmonary Hypertension]]): restrictive PFT’S are seen in 20% of cases
  • Pulmonary Hypertension (see Pulmonary Hypertension, [[Pulmonary Hypertension]])
• PFT Features
  • Generally mild restriction

Poor Cooperation

• PFT Features
  • xxxx

Miscellaneous

• Beta Thalassemia Major (see Thalassemias, [[Thalassemias]]): restriction may occur (for unclear reasons)
  • Pulmonary function test (PFT) defects correct with transfusion and do not correlate with the iron burden, blood counts, or degree of hemolysis

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References

• xxx