The ventilator is alarming: high pressure, low pressure, and what you do first

The rule above the tree

Assess the patient before the machine. If the patient is deteriorating and the cause is not obvious within seconds, disconnect from the ventilator and manually ventilate with a bag-valve-mask on high-flow oxygen while someone else troubleshoots. This single move is the escape hatch from any depth of the tree.

Panel 1 · High pressure means resistance rose or the lung got stiff

• Secretions or a mucus plug. The most common cause by a wide margin.
• Biting on the tube, or a kinked circuit.
• Coughing, or the patient fighting the ventilator.
• Bronchospasm.
• Water pooled in the dependent loop of the circuit.
• The two dangerous ones: pneumothorax and flash pulmonary edema.

First actions. Look and listen for equal chest rise and breath sounds. Suction. Unkink. Place a bite block. Drain the circuit. Treat bronchospasm. If breath sounds are absent on one side with rising pressures and falling blood pressure, stop troubleshooting and call it out loud.

Panel 2 · Low pressure means something is leaking

• Circuit disconnection at any joint, most often at the elbow or the humidifier.
• A loose connection that has not fully separated.
• A cuff leak, which lets the patient vocalize, gurgle, or make sound. A ventilated patient who can suddenly be heard has a leak until proven otherwise.
• A tube that has migrated upward out of position.
• A leaking chest drainage system pulling volume out of the circuit.

First actions. Trace the circuit hand over hand from the patient to the machine. Listen at the mouth and at the neck. Confirm tube depth against the documented centimeter mark at the lip or teeth.

Panel 3 · Which knob fixes which failure

• Oxygenation is corrected with the delivered oxygen percentage and with positive end-expiratory pressure. Pressure recruits collapsed alveoli, at the cost of reduced venous return and increased barotrauma risk.
• Ventilation is corrected with rate and tidal volume, which are what actually move carbon dioxide.
• Assist-control fully supports every breath the patient takes.
• Synchronized intermittent mandatory ventilation supports the mandatory breaths and lets spontaneous breaths be the patient's own size.
• Pressure support assists spontaneous breaths only and is the weaning mode.

Memory hook: DOPE. The vented patient who suddenly deteriorates: Displacement of the tube, Obstruction, Pneumothorax, Equipment failure.

Watch outAn alarm is never silenced before the patient is assessed, and alarm limits are never disabled. Alarm limit policy is institution-specific.

Margin notea cuff leak lets the patient make sound.

Shunt physiology is → BOOK 09 · P4. Sedation and neuromuscular blockade is → BOOK 05 · P6. The ventilator-associated event prevention bundle is → BOOK 04 · P6.

TakeawayHigh pressure is a blocked or stiff lung. Low pressure is a leak. When in doubt, disconnect and bag.