QuestionSBA
QuestionChoice
An obstructive pattern is seen in asthma: FEV1/FVC is less than 0.75. This occurs because the inflammatory bronchoconstriction increases the resistance to airflow, especially during acute attacks in which a wheeze can be auscultated.
10001198
c
Asthma
QuestionChoice
In pulmonary fibrosis, a restrictive pattern is seen in which FEV1/FVC is greater than 0.75. This occurs as the fibrotic lung cannot expand to the same degree as the normal lung but its airways remain open, allowing rapid flow on exhalation. Patients have a decreased capacity to inhale (decreasing forced vital capacity).
10001196
a
Pulmonary fibrosis
QuestionChoice
In healthy lungs, FEV1/FVC is usually 0.75-0.85. Any higher represents a restrictive pattern, whilst lower represents an obstructive pattern. In these conditions, both FEV1 and FVC are often reduced however, one is more decreased than the other, resulting in the characteristic ratios.

<br>
10001200
e
Healthy lungs
QuestionChoice
In cystic fibrosis, an obstructive pattern is seen in which FEV1/FVC is less than 0.75. This occurs as defective CFTR decreases chloride secretion into the alveoli, decreasing osmosis into the bronchioles, and resulting in thick mucus which narrows and blocks the airways.
10001199
d
Cystic fibrosis
QuestionChoice
An obstructive pattern is seen in COPD with emphysema: FEV1/FVC is less than 0.75. This occurs because the bronchioles narrow increasing resistance to flow while the parenchyma loses its elasticity which decreases the ability of the lung to expel air without increased effort. This results in the dichotomy of the 'red puffers' who can expend this increased effort, and the 'blue bloaters' who cannot.
10001197
b
COPD with emphysema
Concept
Chapter
2693
3893
Volume, pressure and compliance
Topic
150
Respiratory physiology
12786
A patient's FEV1/FVC is found to be 0.9.

Which of the following conditions do they most likely have?
a