1. Mechanical Ventilation
Michael Hellmann, MD
Department of Pulmonary-Critical Care

2. https://gizmodo.com/the-last-of-the-iron-lungs-1819079169

3. Invasive Mechanical Ventilation
Decision to Intubate
Initiating Mechanical Ventilation
Oxygenation/Ventilation
Ventilator Problems
Decision to Extubate

4. Indications for Mechanical Ventilation
Respiratory Failure
Oxygenation
Ventilation
Trauma or Surgery
Upper Airway Obstruction
Angioedema
Burns, trauma
Airway Protection
Hematemesis
Prevention of Aspiration
Facilitation of Suctioning
Excessive Secretions
Inadequate cough/clearance

5. Rapid Assessment for Intubation
Clinical Signs of Increased WOB:
Facial Appearance: Mouth open during inspiration, tongue jerking.
Pursed Lip Breathing during exhalation
Speech: Reduced to yes/no questions, unable to speak in full sentences?
Mentation: Early – Anxious, Late – vacant gaze, apathy, then drowsiness, and coma.
Tobin, Martin J. "Principles and practice of mechanical ventilation." (2013).

6. Rapid Assessment for Intubation
Accessory Muscle Usage
Nasal Flaring: Reduces nasal resistance 40-50%, Reduces airway resistance 10-30%.
Prominent Sternomastoid Muscles. Chest wall pulling cricoid cartilage down
Intercostal Recessions
Respiratory Rate: Tachypnea is nearly universally found in respiratory distress
Tobin, Martin J. "Principles and practice of mechanical ventilation." (2013).

7. Rapid Assessment for Intubation
Patient Appearance vs Lab Data
Chest Imaging, Blood Gasses
pH<7.2, Inability to compensate for acidosis
Worsening airspace disease
Trajectory

8. Mr. Breathless 65yoM, COPD, new influenza, SOB
Poor appetite, fevers, losing weight: 6’0, 150lbs
Admitted on CPAP, treating influenza, pneumonia, COPD

9. Mr. Breathless CPAP 8, 100% FiO2, SaO2 84% ABG: 7.12 / 96 / 52
Not expiring CO2
CPAP 8, 100% FiO2, SaO2 84%
ABG: 7.12 / 96 / 52

10. Pressure Control: Inspiratory Pressure 25, PEEP 5, RR 16, FiO2 1.0
Mr. Breathless The decision is made to intubate the 6’0”, 150lb Mr. Breathless. What initial vent settings would be appropriate?
Pressure Control: Inspiratory Pressure 25, PEEP 5, RR 16, FiO2 1.0
Volume Control: Tidal Volume 750mL, RR 16, PEEP 10, FiO2 0.6
Pressure Control: Inspiratory Pressure 25, PEEP 10, RR 25, FiO2 0.6
Volume Control: Tidal Volume 450mL, RR 16, PEEP 10, FiO2 1.0 D

11. Mr. Breathless
The decision is made to intubate the 6’0”, 150lb Mr. Breathless. What initial vent settings would be appropriate?
A) Pressure Control: Inspiratory Pressure 25, PEEP 5, RR 16, FiO2 1.0
B) Volume Control: Tidal Volume 750mL, RR 16, PEEP 10, FiO2 0.6
C) Pressure Control: Inspiratory Pressure 25, PEEP 10, RR 25, FiO2 0.6
D) Volume Control: Tidal Volume 450mL, RR 16, PEEP 10, FiO2 1.0

12. Low Tidal Volume Strategy
ARDS: Berlin Criteria
FOUR CRITERIA
-Timing -Imaging
-Origin of Edema -Oxygenation
Within one week of known clinical event Bilateral opacities (Not explained by effusion, lobar collapse, or nodules) Respiratory failure not fully explained by heart failure or volume overload
PaO2/FiO2 Ratio with PEEP >/= 5: Mild: Moderate: Severe: <100

13. Low Tidal Volume Strategy
Dec’d Vent Complications, Ventilatory Days, Organ Failure, Mortality: 39.8% vs 31%
NNT = 12
ARDS – better outcomes with low tidal volumes
Acute Respiratory Distress Syndrome Network. "Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome." New England Journal of Medicine (2000):

14. Low Tidal Volume Strategy
Ideal Body Weight:
Male: x (Height inches -60)
Female: x (Height inches -60)
Goal Tidal Volume 6mL/kg Ideal Body Weight

15. Ventilation Targets Pressure Control VARIES BY PATIENT Volume Flow
Pressure is Set (Independent)
Volume is Variable (Dependent) on the interaction of the ventilator and the patient’s lung compliance and airflow resistance.
Pressure
SET BY VENT

16. Ventilation Targets Pressure Control Volume Control SET BY VENT Volume
Flow
Flow
Pressure is Set (Independent)
Volume is Variable (Dependent) on the interaction of the ventilator and the patient’s lung compliance and airflow resistance.
VARIES BY PATIENT
Pressure
Pressure

17. Ventilation Targets Pressure Volume Advantages Disadvantages
Reduce peak pressures
Patient synchrony
Disadvantages
Potential for hypoventilation
Potential for overdistension
Advantages
Guarantees constant tidal volume
Control minute ventilation: pH and PaCO2
Disadvantages
Potential for high airway pressures, barotrauma
Potential for Dyssynchrony

18. Mr. Breathless Intubated with low tidal volume strategy.
Stabilizes after Intubation, FiO2 weaned

19. Mr. Breathless The patient is now oxygenating well, but he has a severe respiratory acidosis. His current ventilator settings are Vt 400, RR 16, PEEP 10, FiO Which intervention would provide the most CO2 elimination?
Bicarbonate infusion
Increase RR from 16 to 20 breaths/minute
Increase Vt from 400 to 500 mL/breath
Increase PEEP from 10 cm H20 to 14cm H20 C

20. Mr Breathless
The patient is now oxygenating well, but he has a severe respiratory acidosis. His current ventilator settings are Vt 400, RR 16, PEEP 10, FiO Which intervention would provide the most CO2 elimination?
A) Bicarbonate infusion
B) Increase RR from 16 to 20 breaths/minute
C) Increase Vt from 400 to 500 mL/breath
D) Increase PEEP from 10 cm H20 to 14cm H20

21. Oxygenation
Goals: PaO , SaO2 >88%

22. Oxygenation
PEEP
Lanken, Paul N., et al. Intensive Care Unit Manual E-Book. Elsevier Health Sciences, 2013.

23. Ventilation Acid-Base Goals: 7.30-7.45 (Tolerate 7.20-7.30)
CO2 Goals: Usually Secondary
Minute Ventilation: Respiratory Rate x Tidal Volume
Alveolar Ventilation:
Deadspace Ventilation

24. Mr. Breathless You are called because the patient desaturates even after increasing the FiO2 to Breath sounds are present bilaterally but decreased on the left. No wheezing is noticeable. Peak airway pressure has increased to 50 cm H20 (from 30) but plateau pressure is relatively unchanged at 15. Which intervention is MOST LIKELY to improve the patient’s hypoxia?
Air trapping is present, discontinue patient from the ventilator
Secretions are present and need to be suctioned
Pneumothorax is present and requires needle decompression
Pulmonary edema is present requiring diuresis B

25. Mr. Breathless
You are called because the patient desaturates even after increasing the FiO2 to Breath sounds are present bilaterally but decreased on the left. No wheezing is noticeable. Peak airway pressure has increased to 50 cm H20 (from 30) but plateau pressure is relatively unchanged at 15. Which intervention is MOST LIKELY to improve the patient’s hypoxia?
A) Air trapping is present, discontinue patient from the ventilator
B) Secretions are present and need to be suctioned
B) Pneumothorax is present and requires needle decompression
C) Pulmonary edema is present requiring diuresis

26. Peak vs Plateau Pressure
Volume Control
Volume
Peak Pressure = Airway Resistance
Flow
Plateau Pressure = Total Lung Compliance
Pressure

27. Peak vs Plateau Pressure
Peak Pressure = Airway Resistance
Plateau Pressure = Total Lung Compliance
Airway Secretions
Biting the Tube
Bronchospasm
Foreign Body
Pneumothorax
Right Mainstem ET Tube
Auto-PEEP
Worsening ARDS
Pulmonary Edema
Pleural Effusions
Extrathoracic – Abdominal Pressure

28. Auto-PEEP
Complete Exhalation
Volume
Flow

29. Auto-PEEP
COPD: Prolonged, Incomplete Exhalation
Volume
Flow

30. Auto-PEEP COPD: Prolonged, Incomplete Exhalation
Disconnect Vent, Allow Exhalation
Volume
Flow

31. Consult for tracheostomy Resume sedation and re-evaluate the next AM
Mr. Breathless By day 6 the patient has improved greatly. Ventilator FiO2 is weaned to 30%, PEEP is weaned to 5. In the morning his sedation is lessened and he is placed on continuous positive airway pressure of 5. He breathes 30 times a minute with a minute ventilation of 6 liters/minute. What is an appropriate next step?
Extubate to CPAP
Consult for tracheostomy
Resume sedation and re-evaluate the next AM
Start steroids for airway edema C

32. Mr Breathless A) Extubate to CPAP B) Consult for tracheostomy
By day 6 the patient has improved greatly. Ventilator FiO2 is weaned to 30%, PEEP is weaned to 5. In the morning his sedation is lessened and he is placed on continuous positive airway pressure of 5. He breathes 30 times a minute with a minute ventilation of 6 liters/minute. What is an appropriate next step?
A) Extubate to CPAP
B) Consult for tracheostomy
C) Resume sedation and re-evaluate the next morning
D) Start steroids for airway edema

33. Extubation Criteria Fix Primary Problem?
Is Artificial Airway Required?
Are Lungs Working?
Ventilation
Oxygenation
Lung Mechanics

34. Extubation Criteria Rapid Shallow Breathing Index
Frequency (f) / Tidal Volume (Vt, in L)
>/=105  Increased risk to fail extubation
RSBI = RR/TV(mL); RSBI goal <105
Increased risk of failure.
Yang, Karl L., and Martin J. Tobin. "A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation." New England Journal of Medicine (1991):

35. Extubation Criteria Are the Lungs Working?
Ventilation: Acid/Base, CO2 elimination
Oxygenation: FiO2 Acceptable?
Can you replicate with non-invasive? Generally </= 0.4
Lung Mechanics: Rapid Shallow Breathing Index
Daily Spontaneous Breathing Trial:
Daily sedation holiday paired with weaning trial (CPAP of 5) reduced ventilator days and reduced mortality. NNT to save one life = 7
Girard, Timothy D., et al. "Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (Awakening and Breathing Controlled trial): a randomised controlled trial." The Lancet (2008):

36. Post Extubation CPAP
Planned early NIPPV improves outcomes for marginal extubations
Rescue NIPPV after failing extubation doesn’t work
Future: High flow nasal cannula delivery?
Nava, Stefano, et al. "Noninvasive ventilation to prevent respiratory failure after extubation in high-risk patients." Critical care medicine (2005):
Esteban, Andrés, et al. "Noninvasive positive-pressure ventilation for respiratory failure after extubation." New England Journal of Medicine (2004):