Situation: A 46-year-old woman with severe community-acquired pneumonia and septic shock is in the intensive care unit (ICU). On day 2 she is intubated and diagnosed with acute respiratory distress syndrome (ARDS): her chest X-ray shows bilateral opacities, and an echocardiogram shows normal heart function. She is 160 cm tall and weighs 82 kg. The ventilator's high-pressure alarm sounds, and her oxygen saturation has fallen from 93% to 89%. The nurse hears coarse rhonchi over the trachea and breath sounds on both sides; the trachea is midline, and her blood pressure is unchanged at 112/68 mmHg. The endotracheal tube is not kinked, and she is not biting it. A closed in-line suction catheter is attached to the circuit. What should the nurse do?

A high-pressure alarm with coarse tracheal rhonchi points to secretions in the airway; breath sounds on both sides, a midline trachea, and a stable blood pressure make a tension pneumothorax unlikely, and the tube is neither kinked nor bitten. In ARDS, opening the circuit loses positive end-expiratory pressure and collapses recruited alveoli, so the nurse suctions with a closed in-line catheter. Disconnecting and bagging is reserved for when the cause of the alarm cannot be found quickly.

The high-pressure alarm on a mechanical ventilator signals that the ventilator is encountering increased resistance to delivering a breath. In this patient, the coarse rhonchi heard over the trachea are the key clinical clue: they indicate the presence of thick secretions or fluid within the large airways. Because breath sounds are present bilaterally, the trachea remains midline, and blood pressure is stable, a tension pneumothorax is unlikely. Similarly, the endotracheal tube is not kinked and the patient is not biting it, so a mechanical obstruction of the tube itself can be ruled out. The most probable cause of the sudden rise in airway pressure and the drop in oxygen saturation from 93% to 89% is an accumulation of secretions partially occluding the airway and triggering the alarm.

In a patient with ARDS who is dependent on positive end-expiratory pressure (PEEP) to keep alveoli recruited, disconnecting the ventilator circuit causes an immediate loss of PEEP and can lead to rapid alveolar derecruitment and worsening hypoxemia. For this reason, the closed in-line suction catheter is the preferred method for clearing secretions in this setting. The closed system allows suctioning to occur without breaking the circuit, thereby preserving PEEP, maintaining lung volume, and minimizing the risk of oxygen desaturation during the procedure.

A randomized controlled trial comparing open versus closed suctioning in ARDS patients ventilated with PEEP of 5–10 cmH2O supports this approach ^[1]. The study examined lung volume and oxygenation outcomes and found that closed suctioning better preserved the benefits of PEEP compared with open suctioning, which requires circuit disconnection. Although the abstract does not report the full numerical results, the rationale for closed suctioning in ARDS is directly aligned with the physiological principle of avoiding alveolar collapse.

Additional evidence reinforces the safety and clinical utility of closed-system suctioning. A prospective observational study found that closed-system suctioning can be performed in mechanically ventilated patients while allowing assessment of subjective dyspnea, indicating that the procedure is feasible and does not inherently destabilize the patient when used appropriately ^[2]. Furthermore, research using deep learning to detect respiratory circuit events identified fluid accumulation as a common and clinically significant problem during mechanical ventilation, with 91.7% of patients exhibiting circuit events . This underscores that secretion accumulation is a frequent trigger for ventilator alarms and should be addressed promptly with suctioning.

A bench study on secretion movement during mechanical ventilation also highlights the clinical importance of retained airway secretions as a contributor to ventilator-associated pneumonia and other complications . While that study focused on a different ventilation mode, it reinforces the principle that clearing secretions is a priority when airway resistance increases.

Watch out! Disconnecting the circuit and providing manual breaths with a bag is reserved for situations in which the cause of the high-pressure alarm cannot be quickly identified or the patient is in immediate danger of losing the airway. In this scenario, the cause is identifiable—secretions—and the patient is hemodynamically stable, so disconnection is not indicated.

Key point! The sequence of assessment findings directs the intervention: high-pressure alarm plus coarse rhonchi equals secretions; bilateral breath sounds, midline trachea, and stable blood pressure rule out tension pneumothorax; ARDS with PEEP dependence means the circuit must remain closed. Therefore, suctioning with the closed in-line catheter without opening the circuit is the correct and safest action.