Pulmonary Function Tests
Pulmonary Function Tests (PFTs) might look like squiggly lines and confusing numbers, but they're actually revealing dramatic stories about what's happening inside your patient's lungs. Let's decode these tales!
The Three PFT Patterns You'll See Everywhere
The Obstructive Pattern: The "Trapped Air" Tale
Key Characters: Decreased FEV1, Normal/Decreased FVC, Decreased FEV1/FVC ratio
Starring in: Asthma, COPD, Bronchiectasis, Cystic Fibrosis
The Plot: Air gets in but struggles to get out due to narrowed airways
Visual Clue: Flow-volume loop shows "scooped out" expiratory limb
Treatment Twist: Bronchodilators often improve these numbers dramatically
The Restrictive Pattern: The "Shrinking Lungs" Saga
Key Characters: Decreased FVC, Decreased FEV1, Normal/Increased FEV1/FVC ratio
Starring in: Pulmonary fibrosis, Sarcoidosis, Obesity, Neuromuscular disorders
The Plot: Lungs can't fully expand, but airflow through available airways is normal
Visual Clue: Flow-volume loop looks like a smaller version of a normal curve
Treatment Twist: Bronchodilators typically don't help much here
The Mixed Pattern: The "Double Trouble" Drama
Key Characters: Decreased FEV1, Decreased FVC, Decreased FEV1/FVC ratio
Starring in: COPD with concurrent fibrosis, Cystic fibrosis, Advanced bronchiectasis
The Plot: Two villains attacking simultaneously - trapped air AND reduced lung capacity
Visual Clue: Flow-volume loop shows both reduced volume and scooped expiratory limb
Treatment Twist: Complex and requires addressing both obstructive and restrictive components
Bonus Characters in the PFT Story
RV (Residual Volume): The air that refuses to leave (increased in obstruction)
TLC (Total Lung Capacity): The maximum lung real estate (decreased in restriction)
DLCO: The gas transfer efficiency subplot (decreased in emphysema and pulmonary vascular disease)
Translating PFTs into Plain English for Patients
Instead of saying: "Your FEV1/FVC ratio is reduced at 65% with normal TLC." Try: "Your lungs are good at filling up with air, but they're having trouble emptying completely because the airways are narrower than they should be."
Quick Memory Hack
O-FLAT-R:
Obstructive = FEV1 Low, FVC near normal, FEV1/FVC rAtio Trashed
Restrictive = All volumes Reduced, but ratio preserved
Tomorrow: The respiratory medications cheat sheet you'll want to laminate and keep forever!