A patient on mechanical ventilation develops sudden onset of severe respiratory distress, asymmetrical chest movement, and decreased breath sounds on the right side. The ventilator alarm is sounding with high peak inspiratory pressures. What is the nurse's priority action?

This scenario describes classic signs of tension pneumothorax in a mechanically ventilated patient, which is a life-threatening emergency requiring immediate medical intervention. The priority action is to notify the physician and prepare for chest tube insertion to decompress the pleural space.

Clinical Presentation and Pathophysiology
The patient is exhibiting the classic signs of a tension pneumothorax under positive pressure ventilation. The sudden onset of severe respiratory distress, asymmetrical chest wall movement, and absent breath sounds on the right side indicate that air is accumulating in the pleural space under pressure, collapsing the right lung. The high peak inspiratory pressure (PIP) alarm on the ventilator is a critical mechanical sign: as the pleural space fills with air, it compresses the lung and increases the resistance to lung inflation, causing airway pressures to spike ^[1][4]. This is not a simple mucous plug or equipment issue; the asymmetry and unilateral breath sound loss point directly to a space-occupying problem in the pleural cavity.

The danger of a tension pneumothorax lies in its progression from a pulmonary issue to a hemodynamic crisis. As pressure builds in the affected hemithorax, it pushes the mediastinal structures (heart and great vessels) toward the opposite side. This mediastinal shift kinks the superior and inferior vena cava, critically reducing venous return to the heart. The result is a rapid decline in cardiac output, hypotension, and eventually cardiovascular collapse ^[2][4]. In a patient on mechanical ventilation, positive pressure further forces air into the pleural space with each breath, dramatically accelerating this process compared to a spontaneously breathing patient ^[2].

Priority Action and Clinical Reasoning
The nurse’s priority action is to immediately notify the physician and prepare for chest tube insertion. Tension pneumothorax is a life-threatening emergency that requires immediate decompression to relieve pressure on the heart and lungs. The definitive treatment is the insertion of a chest tube (thoracostomy) to evacuate the air from the pleural space. While the physician performs the procedure, the nurse's role is to prepare the necessary equipment (chest drainage system, sterile supplies) and continue to monitor the patient's airway, breathing, and circulation. Delaying this intervention to try other measures allows the air accumulation and hemodynamic compromise to worsen, potentially leading to cardiac arrest ^[2].

Analysis of Incorrect Options
- Option 1: Increase the FiO2 to 100% and call the respiratory therapist. While increasing oxygen to 100% is an appropriate supportive measure for any acute respiratory distress, it does not address the underlying cause. The hypoxemia here is due to a collapsed lung and shunting of blood, not just a ventilation-perfusion mismatch that more oxygen can fix. Calling a respiratory therapist is helpful but delays the definitive, physician-required intervention of decompression.
- Option 2: Suction the endotracheal tube and reposition the patient. This action addresses a potential endotracheal tube obstruction or migration, which could cause high pressures and unequal breath sounds. However, suctioning would not produce the combination of sudden onset, severe distress, and complete loss of breath sounds on one side with a hyperresonant, overexpanded chest. Repositioning a patient with an untreated tension pneumothorax is dangerous and will not solve the problem.
- Option 3: Administer prescribed sedation to reduce patient anxiety. The patient’s distress is a physiological response to air hunger and impending shock, not a primary anxiety state. Administering sedation could depress the patient’s respiratory drive and hemodynamic status further, masking the clinical signs without treating the mechanical cause of the crisis.

Key Pathophysiological Link to Mechanical Ventilation
The provided literature reinforces why this scenario is particularly perilous. In a patient on positive pressure ventilation, even a small initial pleural injury can rapidly evolve into a tension pneumothorax. The ventilator continuously forces air into the pleural space with each breath cycle, creating a one-way valve effect where air enters but cannot exit ^[2]. This explains the rapid deterioration seen in the case reports, where patients under general anesthesia or in the ICU developed sudden hypoxemia, hypercapnia, elevated PIP, and hemodynamic instability, requiring immediate decompression ^[1][4]. The nurse must recognize that high PIP plus unilateral breath sounds and asymmetry in a ventilated patient is a tension pneumothorax until proven otherwise, and the only correct nursing response is to prepare for immediate pleural decompression .