1. Mechanical Ventilation in the ICU: What You Need to Know
Behrouz Jafari, M.D
Pulmonary/Critical Care and Sleep Medicine
UCI-VA Long Beach

2. Mechanical Ventilation
NIPPV
When to intubate
Setting the ventilator
Complications of mechanical ventilation
Weaning

3. What type of respiratory support should
Case Study
65-year-old with COPD exacerbation using accessory muscles and wheezing after 2 bronchodilator treatments
HR 110/min, BP 160/110 mm Hg, RR 30/min, T 99F
ABG on 3 L/min O2: pH 7.24, PCO2 60 mm Hg, PO2 65 mm Hg
Present case and then reveal question.
Ask what is the main problem-- oxygenation or ventilation.
As students respond, note that positive pressure ventilation may be noninvasive or invasive. Note that noninvasive ventilation may be an appropriate trial for this patient.
What type of respiratory support should
be initiated?

4. NIPPV

5. NPPV: Evidence-Based Recommendations:
Recommended (1A)
» Severe COPD exacerbation (pH < 7.35)
» Cardiogenic pulmonary edema
No shock or ACS requiring revascularization
Suggested (2B-­‐2C)
» Immunocompromised hypoxemic RF (2C)
» Post-­‐op respiratory failure (2C)
abdominal, lung resection
» Facilitation of extubation in high-­‐risk or COPD
Keenan et al. Can Med Assoc J 2011

6. NIPPV Contraindications Poor Mental Status Excess Secretions
Severe Respiratory Failure
Shock
Inability to Protect Airway

7. How should the patient be monitored?
Case Study
ABG on 3L/min O2: pH 7.24, PaCO2 60 mm Hg, PaO2 65 mm Hg
HR 110/min, BP 160/110 mm Hg, RR 30/min
First question about goals of respiratory support appears with case information.
Decrease work of breathing
Improve oxygenation
Improve ventilation
Reveal next question and discuss NPPV settings, how TV is determined and how IPAP and EPAP affect oxygenation and ventilation. Flip chart could be used to write down student suggestions.
Set FIO2 at 1.00
Hypoxemic failure: Inspiratory pressure (IPAP) 10 cm H2O, expiratory pressure (EPAP) 5 cm H2O, titrate EPAP and IPAP in 2 cm H2O increments
Ventilatory failure: IPAP 10 and EPAP 4 cm H2O, titrate IPAP in 2 cm H2O increments
Make changes every minutes
Reveal question on monitoring.
Vital signs, appearance, pulse oximetry and blood gases
If there is time, ask students where patient should be admitted.
How should the patient be monitored?

8. NPPV: Monitoring Patient Ventilator Setting Mask comfort Tolerance
Resp distress
RR, VS
» Accessory muscle use
» Abdominal paradox
Ventilator
Air leak
Adequacy of IPAP (Vt), EPAP
Pt-­‐vent synchrony
SpO2; ABG (2 hr)
Setting
» ICU to start
»SDU if stable

9. What predicts success or failure?
Case Study
After 1 hr of NPPV, the patient has not improved
Arterial blood gas on 40% O2: pH 7.20, PaCO2 65 mm Hg, PaO2 58 mm Hg
HR 120/min, BP 142/98 mm Hg, RR 40 /min
What is the next step?
What predicts success or failure?
Review new case information before revealing question.
Discuss reasons for failure of NPPV and need for intubation.
Clinical worsening
No improvement of ABG in 1-2 hrs
Therapeutic goals not reached

10. NPPV: Predictors of Failure
COPD
» pH < 7.25
» RR > 35/min
» Severely ill
» Asynchrony
» GCS < 11
» Poor tolerance
Hypoxemic Resp Fail
» ALI/ARDS
» Severely ill
» Metabolic acidosis
» P/F < 150 after 1h of
NPPV
» Pneumonia
» Shock
Hill et al. Crit Care Med 2007;35:2402-7

11. NPPV: Predictors of Failure
COPD
» pH < 7.25
» RR > 35/min
» Severely ill
» Asynchrony
» GCS < 11
» Poor tolerance
Hypoxemic Resp Fail
» ALI/ARDS
» Severely ill
» Metabolic acidosis
» P/F < 150 after 1h of
NPPV
» Pneumonia
» Shock
Hill et al. Crit Care Med 2007;35:2402-7

12. Case Study Orotracheal intubation is performed
What ventilator mode should be selected?
What tidal volume is optimum?
What rate of ventilation should be set?
Note that now several settings must be chosen on the ventilator.
Before answering questions, some background information is needed. Proceed to next slides before discussing.

13. Invasive Mechanical Ventilation

14. Breath Characteristics
Trigger, Target, Cycle
Triggering
Cycling
Respiratory Cycle
Expiration
Inspiration
Time (sec)
Airway Pressure (cm H2O)
Discuss determinants of triggering for initiation of inspiration and cycling for termination of inspiration
Triggering: drop in airway pressure or diversion of a constant gas flow
Cycling: volume, decrease in flow rate or elapsed time
Reveal text on types of breaths for discussion.
Volume-cycled breath--Preset tidal volume
Time-cycled breath--Pressure control breath, constant pressure for preset time
Flow-cycled breath--Pressure support breath, constant pressure during inspiration

15. Breath characteristics
Trigger
Controlled - machine timer
Assisted/supported - patient effort
Pressure trigger: Pt effort  pressure drop in vent circuit  vent response
Flow trigger – pt effort  draws gas out of a continuous flow through the vent circuit  vent response
Let’s start with Trigger:is either controlled breath which means the machine timer does it, or is an asissted breath which means patient effort triggered the breath. There are 2 types of trigger , pressure trigger which trigger by change in pressure in circuit (pt effortdrop in pressurevent response). The other common trigger is flow trigger (there is continuous flow of air in the system if pt effortsome flow divert to pt vent response) . Many vent today have both and each one can trigger response.

16. Breath characteristics Gas Delivery (Target)
Now once the breath is triggered , there are 2 basic ways of delivering gas. Here on the left I have flow targeted modes and on the right pressure targeted modes , so here we have a set flow in the system . u set flow of 1 lit/s or 2 lt/sec and machine will deliver no matter what. No matter what your compliance, no matter what your resistance or pt effort is, it will deliver 1 lit /sec. and these are usually couples with volume cycle mechanisms and now airway pressure is dependent variable . So if compliance or resistance gets worse pressure will rise.
Over right we have pressure target breath , so machine change the flow and volume to get that set pressure so now flow and vol are dependent variables, if complaince, resistance changes then flow and vol changes

17. Breath characteristics
Cycle (turning breath off)
Three common types
reach set volume
reach set time
reach certain flow reduction
But what a bout turning the breath off, (cycle) : there common ways : set vol after reach 500 vol then machine stops, which is typical in flow targeted breath. In pressure target there are two ways either set a timer give set pressure for 01 sec 02 sec, or you can have certain flow reduction what does it mean. As you pressurerized the lung the lung expand , flow decrease and to certain point that machine stop the delivery .
Airway pressure is a back up is a safety mechnism u don’t want to over pressure the lung

18. 5 Basic Breath
It is busy but summarize in your vent today . When I called 5 basic breath here , when u look at trigger, target and cycle u can describe these 5 basic breath . Trigger is either timer or patient effort , target is flow or pressure and cycle is either time , volume or flow. So vol controlled breath is machine turns it on is flow targeted and volume cycle. Vol assist is effort triggered , flow targeted and vol cycled
The pressure controlled breath is time trigered pressure targeted and time cycled
Pressure asisst breath is pt trigerred pressure targeted and time cycled . Do we have this? Yes. You can even set rate at 0 but still patient triger breath, pressure targeted and time cycled, so very much like PSV except is time cycled rather than flow cycled.
In PSV is effort, pressure, and flow
These are five basic breath. Now if you mix them with spontanous breath you can describ all modes in MV.

19. 5 Basic Breath
It is busy but summarize in your vent today . When I called 5 basic breath here , when u look at trigger, target and cycle u can describe these 5 basic breath . Trigger is either timer or patinet effort , target is flow or pressure and cycle is either time , volume or flow. So vol controlled breath is machine turns it on is flow targeted and volume cycle. Vol assist is effort triggered , flow targeted and vol cycled
The pressure controlled breath is time trigered pressure targeted and time cycled
Pressure asisst breath is pt trigerred pressure targeted and time cycled . Do we have this? Yes. You can even set rate at 0 but still patient triger breath, pressure targeted and time cycled, so very much like PSV except is time cycled rather than flow cycled.
In PSV is effort, pressure, and flow
These are five basic breath. Now if you mix them with spontanous breath you can describ all modes in MV.

20. 5 Basic Breath
It is busy but summarize in your vent today . When I called 5 basic breath here , when u look at trigger, target and cycle u can describe these 5 basic breath . Trigger is either timer or patinet effort , target is flow or pressure and cycle is either time , volume or flow. So vol controlled breath is machine turns it on is flow targeted and volume cycle. Vol assist is effort triggered , flow targeted and vol cycled
The pressure controlled breath is time trigered pressure targeted and time cycled
Pressure asisst breath is pt trigerred pressure targeted and time cycled . Do we have this? Yes. You can even set rate at 0 but still patient triger breath, pressure targeted and time cycled, so very much like PSV except is time cycled rather than flow cycled.
In PSV is effort, pressure, and flow
These are five basic breath. Now if you mix them with spontanous breath you can describ all modes in MV.

21. 5 Basic Breath
It is busy but summarize in your vent today . When I called 5 basic breath here , when u look at trigger, target and cycle u can describe these 5 basic breath . Trigger is either timer or patinet effort , target is flow or pressure and cycle is either time , volume or flow. So vol controlled breath is machine turns it on is flow targeted and volume cycle. Vol assist is effort triggered , flow targeted and vol cycled
The pressure controlled breath is time trigered pressure targeted and time cycled
Pressure asisst breath is pt trigerred pressure targeted and time cycled . Do we have this? Yes. You can even set rate at 0 but still patient triger breath, pressure targeted and time cycled, so very much like PSV except is time cycled rather than flow cycled.
In PSV is effort, pressure, and flow
These are five basic breath. Now if you mix them with spontanous breath you can describ all modes in MV.

22. Synchronized intermittent mandatory ventilation
Modes of Support
Synchronized intermittent mandatory ventilation
SIMV + PSV
Volume-cycled breath
Spontaneous
Discuss determinants of respiratory rate, tidal volume for volume and time-cycled breaths for SIMV.
Discuss advantages and disadvantages.
Reveal diagram for SIMV+PSV.

23. Setting the Ventilator
Mode
FiO2
Rate
Tidal Volume
PEEP

24. Initiation of Mechanical Ventilation
Initial Ventilator Settings
Minute Ventilation
Metabolic rate is directly related to body surface area (BSA)
Males: = 4 x BSA
Females: = 3.5 x BSA
Nomogram

25. Initiation of Mechanical Ventilation
Initial Ventilator Settings
Minute Ventilation based on BSA
Example:
Female patient with an estimated BSA of 2.0 m2
= 3.5 x 2.0 m2
= 7.0 L/min
A patient’s requirements increase by 9% for every 1° C increase on body temperature

26. Initiation of Mechanical Ventilation
Initial Ventilator Settings
Minute vent.= RR TV
Tidal Volume
VT for an adult is 6 – 8 ml/kg of IBW
Ideal Body Weight Calculation
Male IBW in lb: [6 x (height in inches – 60)]
Female IBW in lb: [5 x (height in inches – 60)]

27. Oxygen Supplementation
Start with 100% after intubation
FiO2 > 60% is (probably) toxic.
Need to balance potential toxicities
Oxygen
PEEP

28. Case Study
What monitoring and assessment is needed after initiation of mechanical ventilation?
Chest radiograph
Vital signs
SpO2
Patient-ventilator synchrony
ABG
Inspiratory pressures
Auto-PEEP
Ventilator alarms
Question appears when slide presented.
Allow students to discuss types of monitoring/assessments before revealing lists. Items in left list will probably be mentioned in the discussion. Items in right list may be new to students. Indicate that these will be expanded on.

29. Proving Endotracheal Intubation
Soft Signs
Equal breath sounds
Easy ventilation
No stomach bubbles
Adequate oxygenation
Firm Signs
Radiograph
Expired CO2

30. 48 yo woman with Group A strep pneumonia, ARDS; arrows to indicate position of the carina and the tip of the ETT at level of aortic knob; note what would happen if flexed or extended neck

31. Inspiratory Pressures
Peak inspiratory pressure (Ppeak)
Inspiratory plateau pressure (Pplat)
Indicator of alveolar distension
Introduce 2 inspiratory pressures and reveal diagram to help explain.
Discuss determinants of pressures.
Ppeak= airway resistance + elastic recoil of lungs and chest wall
Pplat= elastic recoil of lungs and chest wall
Reveal tracing from ventilator to reinforce the measurements.
Ask what the goal is for Pplat and reveal value
Ask what are the consequences of high inspiratory pressures.
Barotrauma
Volutrauma
Decreased cardiac output
Ask how Pplat can be decreased.
Decrease TV
Decrease PEEP

32. Compliance and Resistance
High Peak/High Plateau = decreased compliance
pneumonia, CHF, Pleural Effusion, Pneumothorax, ARDS, ascites, Chest wall abnormalities
High Peak/Low Plateau = increased resistance
secretions, bronchospasm, tubing abnormalities
C=ΔV/ ΔP- ΔV=TV --- ΔP=Pressure Change = Plateau –PEEP
Resistance = (PIP-Plateau)/Flow rate

33. Case Study
18-year-old female found unresponsive at a party (wt 60 kg, ht 64 inches [162.6 cm])
Vomitus in pharynx, difficult intubation
SpO % on 100% oxygen
What is the main problem: oxygenation or ventilation

34. Case Study Assist control (volume) Mode 1.0 FiO2 550 mL Tidal volume
Rate
PEEP
Assist control (volume)
1.0
550 mL
10 breaths/min
5 cm H2O
Use left column of slide to prompt students for responses. Flip chart may be useful to record students choices.
Reveal right column to show what was done for ventilator settings.
Ideal body wt = 56 kg

35. High pressure alarm sounding
Case Study
Mode
FiO2
Tidal volume
Rate
PEEP
Assist control (volume)
1.0
550 mL
10 breaths/min
5 cm H2O
Use left column of slide to prompt students for responses. Flip chart may be useful to record students choices.
Reveal right column to show what was done for ventilator settings.
Ideal body wt = 56 kg
High pressure alarm sounding

36. What problems are present?
Case Study
What problems are present?
SpO2 88% (FiO2 1.0)
Blood gas: pH 7.38, PaCO2 36 mm Hg, PaO2 57 mm Hg
Ppeak 52 cm H2O
Pplat 48 cm H2O
Auto-PEEP 0 cm H2O
Patient’s RR 18/min
Ask what are the major problems for this patient.
Hypoxemia
High inspiratory plateau pressure
Note that ventilation appears adequate

37. Waveform showing decreased lung compliance
‘Square
wave’ flow
pattern
Ppeak
Pplat
Pres

38. Case Study Current Ventilator Settings
What changes in ventilator settings would decrease inspiratory plateau pressure?
Current Ventilator Settings
Assist control (volume)
FiO2 1.0
Tidal volume 550 mL
RR 10/min
PEEP 5 cm H2O
Discuss variables that decrease Pplat
Decrease in tidal volume
Decrease in PEEP
Discuss the consequences of each of the above changes for this patient.
Decrease in tidal volume—decreased minute ventilation and possible hypoventilation
Decrease in PEEP—worsening oxygenation
Discuss compensation for decrease in tidal volume with increase in respiratory rate.
Ask how increase in rate might affect patient interaction with the ventilator.
Discomfort requiring sedation

39. What changes in ventilator settings would improve oxygenation?
Case Study
What changes in ventilator settings would improve oxygenation?
Current Ventilator Settings
Assist control (volume)
FiO2 1.0
Tidal volume 550 mL
Respiratory rate 10 breaths/min
PEEP 5 cm H2O
Discuss variables that affect oxygenation.
FiO2
Mean airway pressure
Possible ventilator changes
Increase PEEP
Increase tidal volume

40. NIH ARDS Network trial NEJM 2000;342:1301
The classic ARDS net trial showing benefits of reducing TV which is associated with improve mortality.

42. Case Study
70-year-old with long smoking history failed NPPV for respiratory distress
Intubated, sedated, and receiving mechanical ventilation
Wt 75 kg, ht 69 inches [175.3 cm])
IBW 70 Kg

44. Case Study Mode FiO2 Tidal volume Rate PEEP AC 1.0 700 mL
12 breath/min
5 cm H2O
Use left column of slide to prompt students for responses. Flip chart may be useful to record students choices.
Reveal right column to show what was done for ventilator settings.

45. What are the major problems? Low blood pressure alarm sounding
Case Study
What are the major problems?
Blood gas: pH 7.20, PaCO2 60 mm Hg, PaO2 215 mm Hg
Pplat 28 cm H2O, Ppeak 50 cm H2O
Auto-PEEP 8 cm H2O
I:E = 1:1.5
RR 18/min
BP 70/30 mm Hg, HR 130/min
Major problems.
Hypoventilation
High peak airway pressure (Note difference between peak and plateau)
Auto-PEEP
Hypotension and tachycardia
Low blood pressure alarm sounding
What do you do next?

46. What are possible causes of the patient’s
Case Study
What are possible causes of the patient’s
hypotension?
Positive intrathoracic pressure (venous return )
Auto-PEEP
Hypovolemia
Tension pneumothorax
Myocardial ischemia
Ask what is the likely cause of the hypotension. Ask for other causes of hypotension after initiation of MV.
Positive intrathoracic pressure due to mechanical ventilation
Auto-PEEP
Hypovolemia
Tension pneumothorax
Myocardial ischemia

47. Auto-PEEP Diagnosis Measurement Waveform analysis Gas flow Auto-PEEP
After discussing development of auto-PEEP, ask what clinical conditions would predispose to auto-PEEP during mechanical ventilation.
Obstructive lung disease (asthma, COPD)
High respiratory rates with high tidal volumes
Auto-PEEP
Auto-PEEP

48. Waveform showing increased airways resistance
Ppeak
Pplat
Pres

50. Recognizing prolonged expiration (air trapping)
Recognize
airway obstruction
when
Expiratory flow quickly tapers off
and then enters a prolonged
low-flow state without returning to
baseline (auto- PEEP)
This is classic for the flow
limitation and decreased lung
elastance characteristic of COPD
or status asthmaticus

51. Auto-PEEP Consequences  Inspiratory pressures Hypotension
Worsened oxygenation
Interventions to decrease auto-PEEP
 Respiratory rate
 Tidal volume
 Gas flow rate
Ask what the consequences of auto-PEEP are before revealing items.
Then discuss ways to decrease auto-PEEP before revealing items.

52. What immediate changes in ventilator settings should be made?
Case Study
What immediate changes in ventilator settings should be made?
Current Ventilator Settings AC
FiO2 1.0
Tidal volume 700 mL
Respiratory rate 12 breaths/min
PEEP 5 cm H2O
Possible changes are aimed at increasing expiratory time.
Decrease tidal volume
Decrease rate (will require sedation of patient)
Decrease PEEP
Increase gas flow rate

53. Obstructive Airway Disease
Initial tidal volume 6-8 mL/kg
Optimize expiratory time
Beware of auto-PEEP
Adjust minute ventilation to low normal pH
Treat obstruction with bronchodilators

55. Mental Status, Sputum Volume & Cough Strength in Weaning
3 Risk factors for failure
» Poor cough
» Heavy endotracheal secretions
» Unable to do all 4 tasks (open eyes, follow with eyes, grasp hand, stick out tongue)
If 2/3 present, 71% sensitive, 81% specific for failure (72h)
Salam et al. Intensive Care Med 2004; 30:1334-9

56. Spontaneous Breathing Trial
Test of breathing for 30 min with minimal ventilatory support
Variables in SBT
» Ventilatory support: T-tube or “flow-by”, < 5 cm H2O CPAP, PSV, or automatic tube compensation
» Termination criteria:
RR > 35 bpm x > 5 min,
SaO2 < 90%,
HR > 140 bpm or sustained HR change > 20%
SBP > 180 or < 90 mmHg,
increased anxiety or diaphoresis

57. Ventilator Emergency I
A 55-year-old patient with ARDS suddenly has a dramatic rise in airway pressures and loss of VT and is starting to desaturate quickly. What is the differential diagnosis?
Sudden worsening of lung disease
Pneumothorax
Atelectasis
Airway obstruction

58. Ventilator Emergency II
A 69-year-old schizophrenic woman with aspiration pneumonia starts to become agitated and starts yelling at you (even though she is intubated). Low VT alarms go off. What is the differential diagnosis?

59. Ventilator Emergency II
A 69-year-old schizophrenic woman with aspiration pneumonia starts to become agitated and starts yelling at you (even though she is intubated). Low VT alarms go off. What is the differential diagnosis?
Self-extubation
Cuff leak

60. Ventilator Emergency III
A 23-year-old female asthmatic is being ventilated with PCV. The blood gas is 7.14/75/102 on: AC12/PCV20/TI0.5/FiO235%/PEEP 0. The RR is increased to 20, the VT’s drop, the PCO2 rises, and the patient becomes hypotensive. What is the differential dx?
Progressive air trapping
Tension pneumothorax

61. What to Report on Rounds
Ventilator Settings
Minute Ventilation (VE)
Pressures
Peak
Plateau
Mechanics
Compliance
Resistance
Auto-PEEP

62. Key Points Goals of NPPV /MV: NPPV is best used in:
support of oxygenation and ventilation and reduction in work of breathing
NPPV is best used in:
Alert, cooperative patient whose condition will improve in hours
Use guidelines when initiating MV and adjust based on monitoring
Maintain low TV 6-8 ml/kg IBW and Pplat 30 cm H2O.
Primary determinants of oxygenation:
FiO2 and mean airway pressure.
Daily evaluation for possible weaning