Pulmonology
Pulmonary questions test spirometry interpretation, obstructive disease management, arterial blood gases, pleural fluid analysis and severity scoring for pneumonia and PE.
Spirometry and COPD
A post-bronchodilator FEV1/FVC below 0.70 confirms airflow obstruction; severity is graded by FEV1 percent predicted (GOLD 1 ≥80, 2 = 50–79, 3 = 30–49, 4 <30). GOLD ABE grouping drives initial therapy: group A a single bronchodilator, group B LABA plus LAMA, group E LABA plus LAMA with inhaled corticosteroid added if eosinophils are 300 or more.
Asthma
Every patient should receive inhaled corticosteroid-containing therapy; reliever-only short-acting beta-agonist strategies are no longer acceptable because of exacerbation and death risk.
Blood gases
Read in order: pH, then PaCO2, then bicarbonate, then compensation. A raised PaCO2 with a normal or high bicarbonate in a breathless COPD patient indicates chronic compensation, not an acute crisis.
Pleural fluid
Light's criteria classify an exudate if any one applies: fluid protein/serum protein above 0.5, fluid LDH/serum LDH above 0.6, or fluid LDH above two-thirds the upper limit of normal serum LDH.
Worked example
Pleural protein 3.8 g/dL with serum protein 6.5 g/dL gives a ratio of 0.58 - above 0.5 - so this is an exudate even if the absolute protein looks modest. Send fluid for cytology, LDH, glucose, pH and culture, and consider malignancy, parapneumonic effusion and tuberculosis.
Traps that cost marks
- Using a fixed 0.70 ratio without considering the lower limit of normal in older adults.
- Treating a COPD exacerbation with inhaled therapy alone when antibiotics and systemic steroids are indicated.
- Calling a transudate without calculating the ratios.