Pulmonary
What you must know
Obstructive disease dominates this domain. Asthma is episodic, reversible, and eosinophilic; COPD is persistent, tobacco-associated, and neutrophilic. Confirm with spirometry: a post-bronchodilator FEV1/FVC below 0.70 defines obstruction, and a 12% plus 200 mL rise in FEV1 indicates reversibility. Asthma therapy escalates from as-needed bronchodilator to low-dose inhaled corticosteroid, ideally as ICS-formoterol used for both maintenance and relief. Every patient with persistent asthma needs an ICS-containing regimen; short-acting beta-agonist monotherapy is inadequate. For COPD, start a long-acting muscarinic antagonist or LAMA/LABA combination, reserving ICS for exacerbation-prone patients with eosinophilia or an asthma component. Restrictive disease shows reduced total lung capacity with a preserved ratio.
Infection and vascular disease: grade community-acquired pneumonia with CURB-65 (confusion, urea elevated, respiratory rate 30 or more, blood pressure under 90/60, age 65 or more). For suspected PE, use pretest probability (Wells) then D-dimer for low or intermediate risk; go straight to CT angiography for high probability. Read arterial blood gases in order: pH, then PaCO2, then bicarbonate.
Traps
- Reflexive high-flow oxygen; in COPD titrate to SpO2 88-92% to avoid hypercarbia.
- Calling a normal chest radiograph exclusion of pneumonia - early disease may not show an infiltrate.
- Excluding PE because the patient is not tachycardic or hypoxic; no single vital sign is sensitive.
- Naming COPD without spirometry, or blurring asthma and COPD in a smoker.
Rule of thumb
A wheezing patient who has never had pulmonary function testing gets symptom relief plus a spirometry order; the ratio that persists after a bronchodilator is what names the disease.