Basics of Ventilator Management

Overview

• Discussion on how to put a patient on a ventilator, initiate mechanical ventilation, and the modes of ventilation.
• Modes include CMV (Controlled Mandatory Ventilation), AC (Assist Control), SIMV (Synchronized Intermittent Mandatory Ventilation), and Spontaneous mode.
• Liberating and weaning a patient off mechanical ventilation.

Indications for Mechanical Ventilation

• Low GCS score: GCS less than 8 indicates need for mechanical ventilation.
• Impaired Oxygenation: Despite 100% oxygen, if the patient does not maintain saturation.
• CO2 Retention: Patient requires ventilation to wash out excess carbon dioxide.

Components of Mechanical Ventilation

• ETT (Endotracheal Tube): Passed through the mouth with an inflated balloon to secure it.
• Ventilator Function: Controls breathing by providing a set volume of air at a certain pressure and rate, mixed with oxygen.

Correlation of Volume and Pressure

• Only one can be set as constant; the other is variable and decided by the ventilator.
  • Set Constant Volume: Ventilator decides pressure.
  • Set Constant Pressure: Ventilator decides volume.

Modes of Ventilation

Controlled Mandatory Ventilation (CMV)

• For patients with very weak or no breathing effort.
• Ventilator provides all breaths; patient is sedated and paralyzed.
• Drawbacks: Disconnection can result in death; risk of barotrauma due to high pressure.

Assist Control Ventilation (AC)

• Allows patient to trigger breaths; ventilator assists.
• Drawbacks: Risk of hyperventilation and respiratory alkalosis if patient breathes too rapidly.

Synchronized Intermittent Mandatory Ventilation (SIMV)

• Weaning mode where patient breathes on their own with intermittent ventilator support.
• Encourages patient effort with periodic assistance from the ventilator.

Pressure Control Ventilation

• Set pressure as constant; volume is variable.
• Preferred in ARDS to avoid barotrauma from high pressures.

Spontaneous Mode

• All effort and breaths by the patient; ventilator provides minimal pressure support.
• Used as a final step before extubation.

Key Terms and Concepts

• Tidal Volume: 6-8 ml/kg of ideal body weight.
• Fraction of Inspired Oxygen (FiO2): Typically started at 80-90%, reduced as patient improves.
• Positive End-Expiratory Pressure (PEEP): Prevents alveolar collapse at end of expiration.

Liberation and Weaning

• Gradual reduction of sedation, transitioning through modes: CMV → AC → SIMV → Spontaneous.
• Monitor ABG parameters (pH, PCO2, PO2) and patient's readiness.

Summary

• Understanding modes and controls of ventilation is crucial for patient safety and effective treatment.
• Prioritize proper settings to avoid complications like barotrauma and alkalosis.

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