1 / 38

Introduction to Mechanical Ventilation

Introduction to Mechanical Ventilation. Spontaneous Breathing. Positive Pressure Breath. Goals of Mechanical Ventilation. Maintain ABG’s Optimize V/Q Decrease Myocardial Workload. Indications for Mechanical Ventilation. Apnea Acute Ventilatory Failure Ph 7.30 or <, with PaCO2 50 or >

Anita
Download Presentation

Introduction to Mechanical Ventilation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Introduction to Mechanical Ventilation

  2. Spontaneous Breathing

  3. Positive Pressure Breath

  4. Goals of Mechanical Ventilation • Maintain ABG’s • Optimize V/Q • Decrease Myocardial Workload

  5. Indications for Mechanical Ventilation • Apnea • Acute Ventilatory Failure • Ph 7.30 or <, with PaCO2 50 or > • Clinical Signs • Impending Ventilatory Failure • Acute Respiratory Failure

  6. Two Ways to Achieve Continuous Mechanical Ventilation, ie CMV • Negative pressure • Positive pressure

  7. Positive Pressure Flow Pattern Considerations Flow = Pressure divided by resistance

  8. Positive Pressure Flow Patterns • Constant flow or Square Wave • Flow stays constant as resistance varies • Thus pressure and resistance vary directly

  9. Positive Pressure Flow Patterns • Accelerating/decelerating or sine wave • Peak flow occurs at mid-inspiration • Mimics spontaneous breathing

  10. Positive Pressure Flow Patterns • Constant Pressure or tapered flow • Flow (and hence tidal volume) vary with resistance

  11. Flow Patterns Summary • Constant flow or square wave • Sine Wave • Constant Pressure or tapered wave

  12. Compare & Contrast

  13. Cycling Cycling refers to how the ventilator ends the inspiratory phase of the breath

  14. Cycling Mechanisms • Volume cycling – inspiration ends when a preset tidal volume is delivered • Pressure cycling – inspiration ends when a preset pressure is reached on the airway • Time cycling – inspiration ends when a preset inspiratory time has elapsed • Flow cycling – inspiration ends when a preset flow has been reached

  15. Triggering The mechanism that starts the inspiratory phase

  16. Trigger Mechanisms • Pressure triggered – a drop in airway pressure triggers the ventilator • Flow triggered – a constant (bias) flow of gas passes through the ventilator circuit. When the patient starts to inhale the ventilator detects the drop in bias flow and triggers • Types of triggered breaths: patient = assisted; ventilator = controlled, operator = manual

  17. Hazards – Positive Pressure CMV • Increased mean intrathoracic pressure • Decreased venous return • Increased intracranial pressure • Pulmonary Volu/Barotrauma • Fluid retention • Gastric Ulcers • Muscle Atrophy & Patient Dependence • Mechanical Failure • Mismanagement • Contamination/Infection

  18. Preventing Hazards • Maintain good I:E ratio • Make sure flow meets patient’s demand • Attention to patient and ventilator • FREQUENT HANDWASHING!

  19. Ventilator “Modes”

  20. Control Mode

  21. Assist Mode

  22. Assist/Control

  23. IMV – Intermittent Mandatory Ventilation

  24. PEEP

  25. CPAP

  26. Other Modes • High Frequency Ventilation (HFV) • Pressure Control ( time cycling) • Pressure Support (flow cycling) • Airway Pressure Release Ventilation (APRV)

  27. Some Practical Applications

  28. Peak Pressure • Pressure on manometer immediately at end of inspiratory phase • Represents pressure needed to overcome both elastic and airway resistance • Used to calculate dynamic compliance • Cdyn = VT/Peak pressure • PEAK PRESSURE WILL CHANGE WHEN EITHER ELASTIC OR AIRWAY RESISTANCE CHANGES!

  29. Plateau Pressure • Pressure on manometer after inspiration has ended but before expiration has started • Represents pressure needed to overcome elastic resistance only • Used to calculate static compliance • Cstat = VT/plateau pressure • PLATEAU PRESSURE CHANGES ONLY WHEN ELASTIC RESISTANCE CHANGES

  30. Clinical Analysis By Comparing Peak and Plateau Pressure Changes • Remember – a change in elastic resistance will affect both peak and plateau pressure • Remember – a change in airway resistance only affects the peak pressure • Compare the change in plateau pressures first, then compare the changes in peak pressure

  31. Resistance and Pressure Vary Directly Resistance and Pressure Vary Inversely With Compliance

  32. Initial Values Peak = 28 cmH2O Plateau = 23 cmH2O 2 Hours later -peak = 32 cmH2O -plateau = 27 cmH2O

  33. Initial Values Peak = 31 cmH2O Plateau = 25 cmH2O 2 Hours Later Peak = 40 cmH2O Plateau = 25 cmH2O

  34. Initial Values Peak = 49 cmH20 Plateau = 30 cmH2O 2 Hours Later Peak = 49 cmH2O Plateau = 26 cmH2O

  35. Initial Values Peak = 36 cmH2O Plateau = 29 cmH2O 2 Hours Later Peak = 32 cmH2O Plateau = 29 cmH20

  36. Initial Values Peak = 29 cmH2O Plateau = 22 cmH2O 2 Hours Later Peak = 41 cmH2O Plateau = 28 cmH2O

  37. Initial Values Peak = 33 cmH2O Plateau = 21 cmH2O 2 Hours Later Peak = 34 cmH2O Plateau = 19 cmH2O

  38. Now lets have some Fun with more math!

More Related