Pernapasan
Core concepts
Build a framework around obstructive versus restrictive disease. Asthma is reversible airflow limitation with episodic wheeze and responds to bronchodilators; COPD is largely fixed obstruction in a smoker with chronic productive cough. Pneumonia diagnosis combines clinical features with consolidation on imaging; use severity scores to decide admission. Know the causes of pleural effusion by transudate versus exudate (Light's criteria), the management of pneumothorax by size and haemodynamic stability, and the recognition of pulmonary embolism using pretest probability plus D-dimer or CT angiography. Understand tuberculosis diagnosis and the principle of multidrug therapy.
Traps
Examiners love the acute severe asthma picture: silent chest, exhaustion, rising PaCO2, and normalising CO2 in a deteriorating patient are red flags, not reassurance. In COPD, controlled oxygen targets avoid hypercapnia but never withhold oxygen in a hypoxaemic patient. Do not mislabel unilateral leg swelling plus dyspnoea as pneumonia. Remember that a tension pneumothorax is a clinical diagnosis requiring immediate needle decompression, not a chest X-ray first.
Worked example
A 24-year-old with sudden pleuritic chest pain and dyspnoea after a long flight has tachycardia and unilateral calf tenderness. Pretest probability is high. Rule of thumb: in a haemodynamically unstable patient with suspected PE, do not send for CT first - treat with systemic thrombolysis or arrange urgent embolectomy; in stable patients, confirm with CT pulmonary angiography before anticoagulation.