Thoracic and Respiratory Disorders
Core approach
Respiratory emergencies require simultaneous airway, oxygenation, ventilation, and perfusion assessment. Understand asthma and COPD exacerbations, pneumonia, pulmonary embolism, pneumothorax, pleural effusion, hemoptysis, ARDS, and acute respiratory failure. Interpret ABGs in context: hypoxemia with a normal A-a gradient suggests hypoventilation, while a widened gradient suggests V/Q mismatch or shunt. Know when to use noninvasive ventilation and when to intubate. For PE, use pretest probability, D-dimer in low-risk patients, and CT angiography when appropriate; unstable patients may need bedside echocardiography and thrombolysis.
Traps
A silent chest in severe asthma is ominous, not reassuring. A rising PaCO2 in asthma signals fatigue and impending failure. Tension pneumothorax is a clinical diagnosis requiring immediate needle decompression, not a confirmatory image. PE can occur with normal oxygen saturation and normal vital signs. Do not attribute all wheezing to asthma; consider anaphylaxis, heart failure, foreign body, and PE. In COPD, avoid excessively high oxygen only when retention risk is documented, but never withhold oxygen from a hypoxemic patient.
Worked example
A young asthmatic has minimal air movement, drowsiness, and a normal-to-high PaCO2 after aggressive bronchodilators. This is impending respiratory arrest, not improvement. Prepare for intubation and continue bronchodilators and steroids. Rule of thumb: in asthma, a normal or rising PaCO2 in a distressed patient means fatigue until proven otherwise.
Key concepts
Know indications for chest tube, needle decompression, and thoracostomy; recognize tracheal deviation late. Use lung-protective ventilation in ARDS and avoid volutrauma.