Overview of Mechanical Ventilation

Use of a machine to augment or supplant native respiration. Goals of mechanical ventilation are to:

• Correct hypoxia
• Correct hypercapnoea
• Minimise VILI
  Avoid excessive lung stretch and cyclic recruitment-collapse.
  • V_T 6mL/kg predicted body weight
  • Pplat <30cmH₂O
  • Adequate PEEP

Indications

Divided into need for:

• Definitive airway
  • Loss of airway reflexes
  • Secretion management
  • Following use of sedation or paralysis
  • Upper airway obstruction
• Respiratory support
  • T1RF
  • T2RF
  • Manipulate physiology
    e.g. CO₂ control for ↑ ICP.
  • Work of breathing

Complications

• Equipment
  • Malfunction
  • Incorrect settings
• A
  • Airway trauma
    • Teeth
    • Cords
• B
  • VAP
  • VILI
  • Barotrauma
    Pneumothorax.
• C
  • RV dysfunction
    • ↓ Preload
    • ↑ Afterload
  • Organ blood flow
    • ↓ RBF
    • ↓ Splanchnic flow
  • Fluid retention
• D
  • Dyssynchrony
  • Complications of sedation
• E
  • Deconditioning
    

Physiological Principles

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References