Initial Ventilator Settings

Jul 14, 2024

Initial Ventilator Settings

Introduction

  • Speaker: Dr. Arushi Chri (PG in Internal Medicine from KIMS Baneshwar)
  • Focus: Initial ventilator settings while ventilating a patient

Key Concepts

  • Understanding initial ventilator settings is crucial for ventilating patients with different conditions.
  • Importance of knowing six key parameters: Mode, FiO2, Tidal Volume, Respiratory Rate, PEEP, and I/E Ratio.

Categories of Patients

1. Normal Lung Function

  • Conditions: GBS, Myasthenia, sudden unconsciousness, without lung pathology.
  • Settings:
    • Mode: Control Mode (Volume or Pressure Control)
    • FiO2: 100% initially, then titrate according to SpO2 and PaO2 (target PaO2 ~80, SpO2 ~94%).
    • Tidal Volume: 6-8 ml/kg body weight (e.g., 420-450 ml for ~70kg patient).
    • Respiratory Rate: 12-14 breaths per minute.
    • Minute Ventilation: 6-7 L/min (Tidal Volume * Respiratory Rate).
    • PEEP: Physiological PEEP (3-5 cm H2O).
    • I/E Ratio: 1:3 (Inspiration:Expiration).

2. Airway Diseases (COPD, Asthma)

  • Challenges: Air trapping, increased airway resistance.
  • Settings:
    • Mode: Control Mode
    • FiO2: Same as normal lung function
    • Tidal Volume and Respiratory Rate: Adjust to maintain minute ventilation.
    • PEEP: Keep low (0-5 cm H2O).
    • I/E Ratio: Increase to 1:4 to 1:6 to allow more time for expiration.

3. Parenchymal Lung Diseases (Pneumonia, Atelectasis, Congestive Heart Failure)

  • Concern: Oxygenation over ventilation.
  • Settings:
    • Mode: Control Mode
    • FiO2: Initially high, then adjust for optimal oxygenation.
    • Tidal Volume: Same as normal lung function (6-8 ml/kg).
    • Respiratory Rate: Higher than normal to maintain minute ventilation (e.g., 16-20 breaths/min).
    • PEEP: Can be increased up to 8-10 cm H2O.
    • I/E Ratio: Adjust to 1:1.5 or 1:2 for improved oxygenation.

4. ARDS (Acute Respiratory Distress Syndrome)

  • Challenges: Severe oxygenation issues, stiff lungs, need for lung protection.
  • Settings:
    • Mode: Preferably Pressure Control
    • FiO2: 100%, then adjust
    • Tidal Volume: 4-6 ml/kg (lung protective strategy)
    • Respiratory Rate: Higher, up to 35 breaths/min
    • PEEP: Can range very high (up to 24 cm H2O)
    • I/E Ratio: 1:1 or inverse (1.2:1)
    • Permissive Hypercapnia: Allow pCO2 to rise when pH > 7.15, use bicarbonate if needed.

Special Scenarios

Patients in Shock

  • Precaution: Ensure fluid resuscitation, possible use of vasopressors to maintain BP during ventilation.

Severe Metabolic Acidosis

  • Settings: Higher initial respiratory rate to maintain compensation (e.g., 24-26 breaths/min)

Neurological Patients (Head Injury, Stroke)

  • Settings: Maintain normocapnia (pCO2 ~32-34 mmHg), minimal PEEP (< 5 cm H2O)

Pneumothorax

  • Settings: Minimal intervention to sustain life until decompression (low respiratory rate, zero PEEP, give fluids, minimal tidal volume).

Conclusion

  • Understanding these categories and settings helps apply principles from critical care manuals and ensures effective patient management.
  • Feedback and further questions can be addressed through comments or forums.