A 57-year-old woman is admitted to the hospital for an elective gastrectomy for a gastric adenocarcinoma. During insertion of a subclavian venous catheter using a right infraclavicular approach, the patient experiences sudden shortness of breath and is obviously uncomfortable in the operating room. Her pulse is 108/min, respirations are 26/min, and blood pressure is 104/64 mm Hg. Physical examination shows jugular venous distention. Breath sounds are decreased on the right.
Which of the following is the most likely diagnosis?
The correct answer is:
E) Tension pneumothorax
Pneumothorax arises when air collects in the pleural space due to injury to the bronchopulmonary parenchyma or penetrating trauma that breaches the pleura. These occurrences can occur during the placement of a subclavian venous catheter. If the air accumulation worsens, it can compress mediastinal structures, impeding venous return and causing obstructive shock (known as tension pneumothorax). Clinically, pneumothorax presents with unilateral diminished breath sounds and hyperresonance upon percussion. Obstruction of venous return leads to jugular venous distension, while shifting of mediastinal structures results in contralateral tracheal deviation. Immediate treatment involves needle decompression or catheter or chest tube thoracostomy. Unstable patients are usually managed with catheter or chest tube thoracostomy.
Answer choice A: Air embolism, is incorrect. Air embolism can occur in both venous and arterial circulations, with risk factors including thoracic trauma, barotrauma, decompression sickness, cardiothoracic surgery, and surgery involving the head and neck. Symptoms vary depending on the embolism's location, commonly presenting as acute shortness of breath, rapid breathing (tachypnea), and chest pain.
Answer choice B: Cardiac tamponade, is incorrect. Cardiac tamponade arises from sudden onset or significant pericardial effusion, leading to compression of the cardiac chambers and obstructive shock. Clinical examination reveals Beck's triad: hypotension, distended jugular veins, and distant heart sounds. Electrocardiography (ECG) may indicate electrical alternans, and there may be pulsus paradoxus upon blood pressure assessment. Treatment is urgent pericardiocentesis.
Answer choice C: Claustrophobia, is incorrect. Claustrophobia, a specific phobia, is characterized by fear of enclosed or tight spaces. It typically does not manifest with unilateral loss of breath sounds during subclavian catheter placement.
Answer choice D: Massive hemothorax, is incorrect. Hemothorax can develop after thoracic trauma or as a complication of thoracostomy placement. Physical examination often reveals diminished breath sounds on the affected side, accompanied by dullness upon percussion. Hemorrhagic shock may ensue due to significant blood accumulation in the hemithorax. Hypovolemia manifests as a flattened jugular vein rather than jugular venous distention.
Key Learning Point
Tension pneumothorax is a life-threatening condition that must be recognized and managed promptly. It occurs when air accumulates in the pleural space, usually due to trauma or a lung condition, creating pressure that compresses the lung and shifts the mediastinum. This compression impedes venous return to the heart, leading to cardiovascular collapse. Clinically, tension pneumothorax presents with respiratory distress, hypotension, tracheal deviation, and decreased breath sounds on the affected side. Immediate treatment involves needle decompression followed by catheter or chest tube insertion to relieve the pressure and restore normal lung function.
