1. MECHANICAL VENTILATION
Marc Charles Parent

2. Presentation Different settings to consider Monitoring of the patient
Different type of patient
COPD, Asthma
ARDS
Trouble shooting

3. Ventilator settings

4. Ventilator settings Ventilator mode Respiratory rate
Tidal volume or pressure settings
Inspiratory flow
I:E ratio
PEEP
FiO2
Inspiratory trigger

5. CMV

6. A/CV

7. SIMV

8. PSV(pressure support ventilation)
Spontaneous inspiratory efforts trigger the ventilator to provide a variable flow of gas in order to attain a preset airway pressure.
Can be used in adjunct with SIMV.

9. Respiratory Rate
What is the pt actual rate demand?

10. Tidal Volume or Pressure setting
Maximum volume/pressure to achieve good ventilation and oxygenation without producing alveolar overdistention
Max cc/kg? = 10 cc/kg
Some clinical exceptions

11. Inspiratory flow Varies with the Vt, I:E and RR
Normally about 60 l/min
Can be majored to l/min

12. I:E Ratio
1:2
Prolonged at 1:3, 1:4, …
Inverse ratio

13. FIO2
The usual goal is to use the minimum Fio2 required to have a PaO2 > 60mmhg or a sat >90%
Start at 100%
Oxygen toxicity normally with Fio2 >40%

14. Inspiratory Trigger Normally set automatically 2 modes:
Airway pressure
Flow triggering

15. Positive End-expiratory Pressure (PEEP)
What is PEEP?
What is the goal of PEEP?
Improve oxygenation
Diminish the work of breathing
Different potential effects

16. PEEP What are the secondary effects of PEEP? Barotrauma
Diminish cardiac output
Regional hypoperfusion
NaCl retention
Augmentation of I.C.P.?
Paradoxal hypoxemia

17. PEEP Contraindication: No absolute CI Barotrauma Airway trauma
Hemodynamic instability
I.C.P.?
Bronchospasm?

18. PEEP
What PEEP do you want?
Usually, 5-10 cmH2O

19. Monitoring of the patient

20. Look at your patient Question your pt Examine your pt Monitor your pt
Look at the synchronicity of your pt breathing

21. Pressures

22. Compliance pressure (Pplat)
Represent the static end inspiratory recoil pressure of the respiratory system, lung and chest wall respectively
Measures the static compliance or elastance

23. Pplat
Measured by occluding the ventilator 3-5 sec at the end of inspiration
Should not exceed 30 cmH2O

24. Peak Pressure (Ppeak) Ppeak = Pplat + Pres
Where Pres reflects the resistive element of the respiratory system (ET tube and airway)

25. Ppeak Pressure measured at the end of inspiration
Should not exceed 50cmH2O?

26. Auto-PEEP or Intrinsic PEEP
What is Auto-PEEP?
Normally, at end expiration, the lung volume is equal to the FRC
When PEEPi occurs, the lung volume at end expiration is greater then the FRC

27. Auto-PEEP or Intrinsic PEEP
Why does hyperinflation occur?
Airflow limitation because of dynamic collapse
No time to expire all the lung volume (high RR or Vt)
Expiratory muscle activity
Lesions that increase expiratory resistance

28. Auto-PEEP or Intrinsic PEEP
Auto-PEEP is measured in a relaxed pt with an end-expiratory hold maneuver on a mechanical ventilator immediately before the onset of the next breath

29. Auto-PEEP or Intrinsic PEEP
Adverse effects:
Predisposes to barotrauma
Predisposes hemodynamic compromises
Diminishes the efficiency of the force generated by respiratory muscles
Augments the work of breathing
Augments the effort to trigger the ventilator

30. Different types of patient

31. COPD and Asthma Goals: Diminish dynamic hyperinflation
Diminish work of breathing
Controlled hypoventilation (permissive hypercapnia)

32. Diminish DHI
Why?

33. Diminish DHI How? Diminish minute ventilation Low Vt (6-8 cc/kg)
Low RR (8-10 b/min)
Maximize expiratory time

34. Diminish work of breathing
How:
Add PEEP (about 85% of PEEPi)
Applicable in COPD and Asthma.

35. Controlled hypercapnia
Why?
Limit high airway pressures and thus diminish the risk of complications

36. Controlled hypercapnia
How?
Control the ventilation to keep adequate pressures up to a PH > 7.20 and/or a PaCO2 of 80 mmHg

37. Controlled hypercapnia
CI:
Head pathologies
Severe HTN
Severe metabolic acidosis
Hypovolemia
Severe refractory hypoxia
Severe pulmonary HTN
Coronary disease

38. A.R.D.S.
Ventilation with lower tidal volume as compared with traditional volumes for acute lung injury and the ARDS
The Acute Respiratory Distress Syndrome Network
N Engl J Med 2000;342:

39. Methods March 96 – March 99 10 university centers Inclusion: Exclusion
Diminish PaO2
Bilateral infiltrate
Wedge < 18
Exclusion
Randomized

40. Methods A/C 28d or weaning 2 groups: End point:
1. Traditional Vt (12cc/kg)
2. Low Vt (6cc/kg)
End point:
1. Death
2. Days of spontaneous breathing
3. Days without organ failure or barotrauma

41. Results
The trails were stopped after 861 pt because of lower mortality in low Vt group

42. Trouble Shooting

43. Trouble Shooting Doctor, doctor, his pressures are going up!!!
What is your next step?

44. Trouble Shooting Call the I.T., he will take care of it!
Where is the staff?
I dont know this pt, and run!
Ask which pressure is going up

45. Trouble Shooting
Ppeak is up
Look at your Pplat

46. Trouble Shooting
If your Pplat is high, you are faced with a COMPLIANCE problem
If your Pplat is N, you are faced with a RESISTIVE problem
DD?

47. Trouble Shooting

48. Trouble Shooting Doctor, doctor, my patient is very agitated!
What is your next step?

49. Trouble Shooting Give an ativan to the nurse!
Give haldol 10mg to the patient!
Take 5mg of morphine for yourself!
Look at your pt!

50. Trouble Shooting
At the time of intubation, fighting is largely due to anxiety
But what do you do if pt is stable and then becomes agitated?

51. Trouble Shooting Remove pt from ventilator Initiate manual ventilation
Perform P/E and assess monitoring indices
Check patency of airway
If death is imminent, consider and treat most likely causes
Once pt is stabilized, undertake more detailed assessement and management

52. Trouble Shooting

53. Conclusion