MedCram Lecture: Modes of Ventilation

Overview

• Focus on additional modes of ventilation
• Primary modes discussed: CPAP and PEEP

CPAP and PEEP

• CPAP (Continuous Positive Airway Pressure):
  • Non-invasive ventilation using a mask (e.g., CPAP or BiPAP mask)
  • Provides continuous pressure irrespective of inhalation or exhalation
  • Pressure range: 5 to 20 cm of water
• PEEP (Positive End-Expiratory Pressure):
  • Used in invasive ventilation
  • Pressure remains even at the end of exhalation
  • Measured in mmHg, can be 5 to 20

Purpose

• Keeps airways open
• Prevents collapse of tiny airways (alveoli)
• Helpful in conditions like obstructive sleep apnea

Other Modes of Ventilation

Pressure Support (PS)

• Similar to CPAP/PEEP but pressure support is provided on inhalation only
• Patient-initiated breaths

Assist Control (AC)

• Patient triggers the ventilator
• Delivers specific volume
• Backup rate can be set
• Commonly used in intensive care units

Writing Ventilator Orders

• Four key settings:
  1. Mode: e.g., AC (Assist Control)
  2. Backup Rate: Ensures minimum breaths per minute
  3. Tidal Volume: e.g., 550 ml
  4. FiO2 (Fractional Inspiration of Oxygen): e.g., 50%
  5. PEEP: e.g., 5

Impact on Physiology

• Carbon Dioxide Regulation:
  • Controlled by breath rate and tidal volume
• Oxygenation:
  • Influenced by FiO2 and PEEP

Graphs and Diagrams

• Pressure-Volume-Flow Graph:
  • Illustrates pressure changes during breaths
  • Shows flow rate and tidal volume changes

Additional Considerations

• Compliance of the lung affects pressure
• Set pressure alarms for safety
• High pressure indicates issues like pulmonary edema or pneumothorax
• Two pressures to monitor:
  • Peak Pressure
  • Plateau Pressure (to be covered in the next lecture)

Next Steps

• Further exploration into pressure settings and their implications on lung mechanics and patient safety.