The Ventilatory Pump and Respiratory Failure

• What is the Ventilatory Pump?

  • It is the mechanism that moves air into and out of the lungs
  • Imagine a set of bellows
• The Ventilatory Pump:

  • The ability to sustain spontaneous ventilation depends on the triad of CNS drive, the capacity of the respiratory muscles, and the load that is imposed upon them
• The Ventilatory Pump - Made up of 3 components:

  • Drive
  • the drive to breathe (CNS)
  • Capacity
  • The ability of the respiratory muscles to generate pressure
  • The ability of the pump to do the pumping
  • Incorporates concepts of strength, endurance and mechanical ability
  • Load
  • The work performed by the respiratory muscles
  • 2 types of load:
  • Resistive load - when increase in airway resistance due to airway narrowing e.g. due to sputum plugging
  • Elastic load - relates to lung compliance - poor compliance increases elastic load on respiratory muscles, so they have to work harder to move air
• The Ventilatory Pump:

  • There is a definite balance between capacity and load
  • If load exceeds capacity what will happen?:
  • Hypoventilation
  • Type 2 respiratory failure -> low o2 and high co2