Ventilator_Graphics_Advanced_Lecture.pptx

Ventilator graphics

1. Ventilator Graphics Advanced Lecture for ICU Resident Doctors 🫁 Comprehensive Waveform Interpretation

2. Introduction to Ventilator Graphics • Ventilator graphics provide real-time visualization of patient-ventilator interaction. • Essential for optimizing ventilation, detecting asynchrony, and ensuring safety. • Three main waveform types: Pressure-Time, Flow-Time, Volume-Time.

3. Pressure–Time Waveform • X-axis: Time | Y-axis: Pressure (cmH₂O) • Reflects inspiratory pressure changes. • VCV: square waveform; PCV: decelerating rise. • Useful for identifying plateau pressure, PEEP, and asynchrony.

4. Flow–Time Waveform • X-axis: Time | Y-axis: Flow (L/min) • Inspiratory flow shape depends on mode. • Expiratory flow should return to zero — failure suggests air trapping or auto-PEEP.

5. Volume–Time Waveform • X-axis: Time | Y-axis: Volume (mL) • Reflects tidal volume delivery. • Helps detect leaks (volume not returning to baseline) and compliance changes.

6. Volume-Controlled Ventilation (VCV) • Fixed tidal volume, variable pressure. • Pressure waveform: square flow pattern. • Indicators: high Ppeak = increased resistance, high Pplat = decreased compliance.

7. Pressure-Controlled Ventilation (PCV) • Fixed pressure, variable volume. • Flow decelerates as alveoli fill. • Useful for ARDS and poor compliance states.

8. Flow Patterns & Triggering • Trigger: patient effort or ventilator. • Types: pressure-triggered, flow-triggered. • Ineffective triggering → small dips in pressure curve without breath delivery.

9. Cycling and Termination • Volume-cycled: ends after set volume. • Pressure-cycled: ends at set pressure. • Flow-cycled: ends when flow drops to % of peak (common in PSV). • Time-cycled: ends after set inspiratory time.

10. Troubleshooting Abnormal Graphics • Auto-PEEP: expiratory flow not returning to baseline. • Leak: incomplete volume return. • Obstruction: scooped flow pattern. • Low compliance: steep pressure rise.

11. Patient–Ventilator Asynchrony • Types: Trigger, Flow, and Cycle asynchrony. • Double triggering: two breaths per effort. • Ineffective effort: small pressure dips without inspiration. • Flow starvation: concave pressure curve.

12. Disease-Specific Patterns: ARDS • Poor compliance → high pressure, low volume. • Use low tidal volume (6 mL/kg) and monitor plateau pressure (<30 cmH₂O). • Waveform: high PIP, rapid pressure rise.

13. Disease-Specific Patterns: COPD / Asthma • Increased airway resistance. • Expiratory flow takes longer → auto-PEEP common. • Manage with prolonged expiratory time and low RR.

14. Disease-Specific Patterns: Neuromuscular Weakness • Weak patient effort → delayed triggering. • Risk of hypoventilation and asynchrony. • Adjust trigger sensitivity and support mode.

15. Summary • Ventilator graphics are vital for safe and effective ventilation. • Recognize normal and abnormal waveforms. • Identify and correct asynchrony early. • Tailor ventilation mode to underlying pathology.

16. References 1. Tobin MJ. Principles and Practice of Mechanical Ventilation, 3rd ed. 2. Pilbeam SP. Mechanical Ventilation: Physiological and Clinical Applications. 3. Marini JJ, et al. Critical Care Medicine Reviews.