1. Mechanical Ventilation
Mike Haines, MPH, RRT-NPS, AE-C

2. Selecting the Ventilator and the Mode

3. Indications Acute ventilatory failure Impending ventilatory failure
Severe Hypoxemia
Prophylactic Support

4. Acute Ventilatory Failure
PaC02 > 50 mm Hg with pH < 7.30.
Apnea
Hypoxemia

5. Impending Ventilatory Failure
Pt maintains marginally acceptable blood gas values at the expense of significant increased WOB.
Progressive acidosis and hypoventilation ensue.

6. Severe Hypoxemia
Pa02 < 60 mm Hg on Fi02 of 50% or greater.

7. Prophylactic Ventilatory Support
Risk of pulmonary complications
Reduce hypoxia of major body organs
Reduce cardiopulmonary stress

8. Considerations Patient’s informed request. Medical futility
Termination of pts pain and suffering.

9. Initial Ventilatory Settings
Invasive vs. Non-invasive
Mode
Full or partial support
Control
CMV – A/C
SIMV/IMV
CPAP/Spontaneous

10. CMV Continuous Mandatory Ventilation
Total ventilatory support is provided by the ventilator.
Volume Control
Indicated when a precise minute ventilation or blood gas parameter is essential.
Pressure Control
When adequate oxygenation has been difficult to achieve.

11. VC: Volume limited, flow cycled, pressure and I-time variable
PC: Pressure limited, time cycled, volume and flow variable
PRVC: Volume targeted, pressure limited, time cycled, flow varible

12. Assist/Control – A/C mode
Set RR and Vt or Pressure
Patient can increase ventilator rate or assist in addition to the preset rate.
Each assisted breath results in the patient receiving the preset Vt or inspiratory pressure.

13. Assist/Control – A/C mode
This mode does not allow for spontaneous breathing.
What triggering mechanisms can be active in A/C?
What cycling mechanisms can be active in the A/C mode?
Time – Controlled Breath
Patient – Assisted Breath (Flow or pressure)
Cycling – Volume, Time, Pressure Limit
Manual

14. IMV Intermittent Mandatory Ventilation
IMV allows or requires the patient to sustain some of the work of breathing.
Volume Control
For patients with normal lung function recovering from sedation or rapidly reversing respiratory failure.
Pressure Control
Preservation of patient’s spontaneous effort is important but adequate oxygenation has been difficult to achieve.

15. Synchronized Intermittent Mandatory Ventilation - SIMV
Set RR and Vt or Pressure
Patient is allowed to breathe spontaneously at any tidal volume the patient is capable of in between mandatory breaths

16. PSV
PSV only applies to spontaneous inspiratory breaths, used to augment spontaneous VT, set to achieve spontaneous VT of 5-7ml/KG, set above measured RAW
Start with a PSV of about 10, titrate or increase as needed. PSV max = 20-25
Pressure limited, patient cycled, set sensitivity and rise time, e-sens

17. SIMV
Mandatory breaths are synchronized with the patient’s spontaneous breaths to minimize breath stacking.
Provides partial ventilatory support

18. SIMV - Advantages Maintains respiratory muscle strength
Reduces V/Q Mismatch
Decreases MAP
Facilitates weaning

19. SIMV What triggering mechanisms can be active in SIMV?
What cycling mechanisms can be active in the SIMV mode?

20. CSV Continuous Spontaneous Ventilation
CPAP, PSV, automatic tube compensation (ATC), proportional assist ventilation (PAV).
Breaths initiated and terminated by the patient.
Indications: Reduce WOB, and improve or stabilize oxygenationby reducing alveolar derecruitment.

21. CPAP or Spontaneous Mode
All breathing is done by the patient
Patient can be supported with pressure support and/or CPAP
Ventilator provides inspiratory flow to the patient.
Ventilator monitors Vt, Ve and RR

22. Pressure Support Ventilation - PSV
Applies a preset pressure plateau to the patient’s airway for the duration of spontaneous breathing.
Used only in ventilator modes that allow for spontaneous breathing

23. Pressure Support Ventilation - PSV
Patient has control over
Tidal Volume
Inspiratory Time RR
What is the cycling mechanism for Pressure supported breaths?

24. Ventilator Settings Respiratory Rate or Frequency Fi02
Tidal Volume or Inspiratory Pressure
Peak Flow or Inspiratory Time
Flow Pattern
PEEP
Sensitivity
Pressure Support Level

25. Humidification
The gas delivered to patient during mechanical ventilation should be filtered, humidified, and heated between 32 to 34 C.
Heated humidifier or HME

26. PEEP Increases the baseline airway pressure. Two major indications
Shunt and refractory hypoxemia
Decreased FRC and lung compliance

27. Complications of PEEP Decrease venous return Barotrauma Increased ICP
Alterations in renal function and H20 balance
Alterations in liver function.

28. I:E Ratio
The ratio of inspiratory to expiratory time.
Kept 1:2 to 1:4

29. I:E Ratio
Longer I times used to increase mean airway pressure and improve oxygenation.
Longer E times used on pts to reduce the possibility of air trapping and auto peep.

30. Factors Effecting I:E Ratio
Flow rate
Tidal Volume RR
Peak Flow
Flow Pattern
Inspiratory Time

31. When you make changes to rate of tidal volume/or pressure limit, you may have to adjust flow or I-time to maintain I:E ratio