What are some causes of the low pressure limit on a ventilator?

• A. Loss of airway (exubation), endotracheal or tracheostomy cuff leak, or tubing disconnect
• B. High airway resistance due to secretions
• C. Increased lung compliance due to obesity
• D. Cardiac arrhythmia

Answer: (A)

Low pressure limit indicates the system isn’t able to maintain the set inspiratory pressure, usually because gas is leaking out of the circuit or airway. The best explanation is a leak in the airway or circuit: loss of the airway from extubation or tube dislodgement, a cuff leak around the endotracheal/tracheostomy tube, or a disconnected or damaged tubing circuit. Each of these creates a path for gas to escape before reaching or sustaining the airway, so the ventilator senses a drop in pressure and alarms.

The other possibilities don’t fit this alarm as well. High airway resistance from secretions tends to raise pressures (high peak inspiratory pressure) rather than drop them. Increased lung compliance and obesity-related changes don’t typically produce a low pressure alarm, and a cardiac arrhythmia isn’t directly a cause of a low inspiratory pressure event. If this alarm occurs, check for leaks, cuff integrity, and any circuit disconnections.