MECHANICAL VENTILATION - Volume/Pressure Alarms

Causes for high pressures/low tidal volumes are:

• Excessive tidal volume (only with high pressure alarm)
• Endobronchial intubation (trying to inflate one lung with with a breath for two lungs)
• Patient actively expiring during the ventilators inspiratory cycle (Patient-Ventilator dyssynchrony)
• ETT obstruction (e.g. kink, secretions)
• Narrowed lower airways (e.g. asthma/COAD, anaphylaxis)
• Stiff lungs (e.g. pulmonary fibrosis)
• Stiff chest wall (e.g. obesity)
• Pneumothorax

Causes for low pressures/high tidal volumes:

• Leaks in the system
  • Disconnection
  • Cuff leak
  • Oesophageal intubation

Take a while to think why these conditions might cause these problems.

Problems with airway pressures or tidal volumes should be immediately addressed.   If these problems occur then you should take the following steps:

• Disconnect the patient from the ventilator and ventilate by hand (Eliminate the ventilator)
• Immediately exclude ETT blockage and replace if concerned, check the ETT for leaks
• Examine the chest - check for unequal air entry (endobronchial intubation, pneumothorax), wheeze (bronchospasm)
• Treat any problem you find
• Reconnect the patient to the ventilator
• If problems persist consider reducing the tidal volume or get a new ventilator