Surgical Critical Care: Mechanical Ventilation – Complications

Complications of Mechanical Ventilation

Intubation/Endotracheal Tube Complications

  • Local Trauma
  • Endotracheal Tube Obstruction or Occlusion
  • Esophageal Intubation
  • Right/Left-Mainstem Bronchus Intubation
  • Aspiration
  • Tracheal Stenosis/Necrosis

Ventilator-Induced Lung Injury (VILI)

  • Atelectrauma – Trauma from the Shear-Stress Created by Recruiting/Opening Atelectatic Alveoli
    • Stress is Exacerbated by Lung Inhomogeneity (Seen in Atelectasis, ARDS, Surfactant Deficiency & Pulmonary Edema)
  • Barotrauma – Trauma from High Inspiratory Pressure Causing Alveolar Over-Distention
    • Can Cause Alveolar Rupture with Air Leakage, Pneumothorax & Pneumomediastinum
  • Volutrauma – Trauma from Increased Volume Causing Alveolar Over-Distention
  • Biotrauma – Additional Injury Due to the Inflammatory Response to Mechanical Injury

Dynamic Hyperinflation (DHI)

  • Definition:
    • Air Trapping (Air Stacking): Hyperinflation (Increased End-Expiratory Lung Volumes) Due to Incomplete Exhalation
    • Auto PEEP (Intrinsic PEEP/PEEPi): Increased Positive End Expiratory Pressure from Hyperinflation
  • Most Commonly Associated with COPD Exacerbation, Asthma & ARDS
  • Causes:
    • Decreased Expiratory Time
    • Excessively High Minute Ventilation (High Tidal Volume or Respiratory Rate)
      • *Increasing Vt or Rate for Hypercarbia Can Actually Worsen Hypercarbia
    • Increased External Airflow Resistance
    • Persistent Respiratory Muscle Inspiratory Activity During Expiration
    • Increased Compliance (Reduced Elastic Recoil)
  • Effects:
    • Alveolar Over-Distention & Barotrauma
    • Decreased Compliance
    • Decreased Venous Return, Preload & Cardiac Output
  • Identification:
    • Ventilator Graphics Show Airflow Failing to Return to Zero at End-Expiration
    • Can Measure by Performing an “End-Expiratory Hold” – Escaping Trapped-Air Will Increase Airway Pressure
  • Management:
    • Decrease Inspiratory Time & Increase Expiratory Time (Decreased I/E Ratio)
      • Increase Inspiratory Flow Rate (IFR)
      • Decrease Tidal Volume
      • Decrease Respiratory Rate
      • *Allow for Permissive Hypercapnia (Avoid pH < 7.20 – Risk for Hemodynamic Instability)
    • Bronchodilators
    • Improve Ventilator Synchrony
    • Immediately Disconnect the Ventilator if Concerned for Severe Auto PEEP Causing Cardiovascular Collapse

Other Complications

  • Ventilator-Induced Diaphragmatic Dysfunction (VIDD)
    • Diaphragm Muscle Atrophy & Contractile Dysfunction
    • Caused by Oxidative Stress, Protein Imbalance & Myotrauma
  • Ventilator-Associated Pneumonia (VAP)
  • Gastritis & Peptic Ulcer
  • Oxygen Toxicity