A therapist observes a sudden low return volume alarm on a ventilator. What is the likely cause?

The observation of a sudden low return volume alarm on a ventilator typically indicates an issue with the patient circuit or the patient's condition that affects the ventilation parameters. A bronchopleural fistula is a direct communication between the bronchial tree and the pleural space, which can lead to a significant loss of tidal volume and cause alarms related to low return volumes. In this scenario, the presence of a bronchopleural fistula would allow ventilated air to escape from the lungs into the pleural space, reducing the volume of air that is detected by the ventilator's return volume measurement.

This condition is particularly critical, as it not only compromises ventilation but also can lead to lung collapse (pneumothorax) and significant respiratory distress. Identifying the bronchopleural fistula is essential in such cases since it requires intervention to manage the air leak and restore effective ventilation.

Other potential causes for low return volume alarms, such as pulmonary embolism or ARDS, typically present with other clinical signs and do not primarily result in a low return volume on the ventilator. Excess condensate in the ventilator circuit may lead to other issues but is less likely to cause a sudden drastic change in return volumes compared to a bronchopleural fistula