Description of how to set up and modify mechanical ventilator settings

1. VENTELATOR SETTINGS
DR- ATEIA EL MEHDOWI

3. :
CONTENTS
• Manipulation of ventilators .
• Components of ventilator .
• Initial ventilator settings .
• Safety considerations in mechanical ventilators .
• Golden rules in mechanical ventilation .

4. Manipulation of ventilators
The adjustment of ventilators requires recognition of:
1. Clinical and metabolic condition of the patient.
2. Characteristics of the machine.
3. A base line ABG is absolutely essential to determine
the starting point for treatment of hypercapnia and
acidosis and/or hypoxia.
The PaCO2 level dose not have the same importance as
pH level, since patient consciousness varies with acute
versus chronic hypercapnia.

5. There should be a manual resuscitation bag at the
bedside of every patient receiving mechanical ventilation.
Ventilators are a method of life-support; if the ventilator
stops working ??????

6. Physician
Nurse
RT
Patient
Ventilator
Success of mechanical ventilation

7. COMPONENTS OF VENTILATORS
Grouped into 4 categories:
1. Controls.
3. Alarms
2. Monitors.
4. External features & accessories.

8. CONTROLS

9. CONTROLS
The number and type of controls in specific
ventilator depend mostly on their purpose.
 Critical Care
 Neonatal Intensive Care
 Pediatric Intensive Care Unit
 Post Anesthesia Care Unit (PACU)
 Home
 MRI
 Transport – Ground/Air/Hospital
 OR

10. A. Short-term ventilators: have fewer controls.
CONTROLS

11. They are more
difficult to operate.
A. Long-term ventilators:
They have large variety of controls
They have great
flexibility in clinical
application
CONTROLS

12. CONTROLS

13. CONTROLS

14. 2- Microprocessor-controlled ventilators

15. Microprocessor-controlled ventilators

16. • Pressure.
• Volume (Vm & Vt ).
• Rate.
• FIO2.
• I/E ratio or I/E time.
• Insp. Flow.
• Sensitivity.
• Insp. Pause (inflation hold).
• PEEP.
• Sigh (volume & frequency).
CONTROLS

17.  Tidal volume (Vt)
The clinician sets:
 Frequency
 Trigger sensitivity.
 PEEP
VCV

18. (PCV)
The clinician sets:
 Peak inspiratory pressure (PIP)
. (Complete control of peak pressure).
 Frequency
 Inspiratory time (It).
 Rise time
 Trigger sensitivity.
 PEEP

19. e.g.. VCVs do not provide an independent pressure control.
• Control on ventilators may provide an approximate values.
To confirm the accuracy of controls, an effective monitoring
capability is needed.
e.g.. PCVs do not provide an independent volume control.
• There are several functions for the ventilators have no controls,
yet these must be monitored
CONTROLS ..

21. INITIAL VENTILATOR SETTINGS
Mode of ventilation
• The initial mode of ventilation should be the assist
control (A/C) mode.
• In the A/C mode, the work of breathing is reduced to
only that amount of inspiration needed to trigger the
machine's inspiratory cycle.
• A second possible advantage is that cycling the
ventilator into the inspiratory phase maintains normal
ventilatory activity and, therefore, prevents atrophy of
the respiratory muscles.

22. The potential disadvantages of the A/C mode include
respiratory alkalosis.
A second possible disadvantage is that every breath is
a full, preset, positive-pressure breath that influences
venous return to the right heart and, possibly, to
global cardiac output.
Nevertheless, the A/C mode is the best initial mode of
ventilation and may be switched to another option if
hypotension occurs or hypocarbia is evident on the
first arterial blood gas analysis.

23. Fractional Inspired Oxygen (FIO2)
The fractional inspired oxygen is the amount of oxygen
delivered to the patient.
It can range from 21% (room air) to 100%.
It’s recommended that the FIO2 be set at 1.0 (100%)
upon the initiation of mechanical ventilation to allow
the patient to get used to the ventilator without
experiencing hypoxia.

24. A short period on FIO2 of 100% is not
dangerous to the patient on mechanical
ventilation and offers the clinician several
advantages:
• protects the patient against hypoxemia
if unrecognized problems develop from
the intubation procedure.
• PaO2 measured on an FIO2 of
100%, the clinician can easily
calculate the next desired FIO2 and
quickly estimate the shunt fraction.

25. When the clinician wishes to change the PaO2,
2 variables might be adjusted
FIO2 and the amount of PEEP.
When using supplemental FIO2, improvement in
oxygenation cannot reliably be achieved with changes
in rate or tidal volume.
With the target PaO2 identified, the FIO2 can be
adjusted using the formula:
New FIO2=(old FIO2 X desired PaO2)/measured PaO2.

26. The degree of shunt on 100% FIO2 can be
estimated by a rough rule of thumb.
The measured PaO2 is subtracted from 700 mm
Hg. For each 100 mm Hg difference, a 5% shunt
exists.
A shunt of approximately 25% requires the use of
PEEP.

27. Positive end-expiratory pressure [PEEP]
PEEP therapy can be effective when used in patients
with a diffuse lung disease that results in an acute
decrease in functional residual capacity (FRC)
when used to treat patients with a diffuse lung disease,
PEEP should improve compliance, decrease dead space,
and decrease the intrapulmonary shunt effect. The most
significant benefit of PEEP is that the patient can
maintain an adequate PaO2 at a lower, safer
concentration of oxygen (<60%), thereby reducing the
risk of oxygen toxicity.

28. No recommendations exist for adding external PEEP
during initial ventilator setup to satisfy misguided
attempts to supply prophylactic PEEP or physiologic
PEEP.
Most clinicians use the lowest amount of positive
pressure that provides an adequate PaO2 with a safe
FIO2.
PEEP

29. PEEP principally is used to lower the risks of oxygen
toxicity and is employed when a safe PaO2 cannot be
achieved at 60% FIO2.
Initiated at 5 cm H2O, PEEP usually is increased in
3 cm H2O increments, while evaluating the effect on
oxygenation every 15-20 minutes.
A PEEP level of 10 cm H2O rarely causes
hemodynamic problems in the absence of
intravascular volume depletion.

30. changes in PEEP may not be reflected by changes in
arterial blood gases for 20-30 minutes so changes
in the PEEP setting should usually not be made
faster than this
PEEP over 20 cm is rarely beneficial and usually
results in additional pressure-induced lung injury

31. BEST PEEP ?
The exact amount of PEEP applied is very
controversial
?????????????????????????????????

32. Pressure (cm H2O)
0 50
Volume
(ml)
1500
0
Alveoli elastic limit
UIP
LIP Alveoli open
Alveolar collapse
PEEP
Pressure limit
Pressure-volume curve

33. The titration of PEEP above the lower
inflection point  increases lung compliance
“best PEEP”.
The titration of PIP below the upper inflection
point  prevention of over destintion
Pressure-Volume loope

34. 400
600
200
0 5 10 20 30 40 50
Press
Vt
300
500
700
100
Lower inflection point
Upper inflection point
PIP
PEEP
Pressure-Volume loope

36. The respiratory rate is the number of breaths
that
the ventilator delivers to the patient each
minute.
The rate chosen depends on the :
1. Tidal volume.
2. Type of pulmonary pathology.
3. patient’s target PaCO2.
Respiratory Rate (RR)

37. Patients with restrictive lung disease usually
tolerate a range of 12-20 breaths/minute.
Patients with normal pulmonary mechanics can
tolerate a rate of 8-12 breaths/minute.
For patients with obstructive lung disease, the
rate should be set at 6-8 breaths/minute to avoid
the development of auto-PEEP and
hyperventilation, or “blowing off CO2.”. Patients
with obstructive lung disease often adapt to a
higher PaCO2, so lowering it back to the “normal”
range of 35-45 mm Hg may not be beneficial.

38. The respiratory rate parameters are set above
and below this number and the alarm will
then sound if the patient’s actual rate is
outside of the desired range.

39. The usual setting is 5-12 cc/kg.
based on compliance, resistance, and type of
pathology.
Tidal Volume (VT)
• Patients with normal lungs can tolerate a tidal
volume of 10-12 cc/kg,
• Patients with restrictive lung disease may
need a tidal volume of 5-8 cc/kg.

40. Tidal Volume (VT)
Males Ideal body weigh IBW =50+2.3 (Height (inches) – 60 )
Females Ideal body weigh IBW =50+2.3 (Height (inches) – 60 )

41. The tidal volume alarm level are set above and below
the desired number, and the alarm will sound if the
patient’s actual tidal volume is outside of the desired
range.
Tidal Volume (VT)

42. Double-checking the selected tidal volume
After a tidal volume is selected, the peak airway and
Plateau pressures pressure should be determined
peak airway pressure <45 cm H2O.
plateau pressure is <30-35 cm H2O.

43. Tow Pressure level :
 Small values, which just to compensate for
resistance of the ETT.
 Large values, that make the spontaneous breath
equivalent to triggered mandatory breath (PCV).
Pressure suppot PS

44. Pressure
support
PS only eliminates the work precisely at a given flow.
Above and below that flow, PS under compensates for
resistance or over compensates.

45. (Weaning)
ATC
ATC compensation can overcome resistance
regardless of patient flow demand.

46. The I:E ratio is usually set at
1:2 or 1:1.5
to approximate the normal
physiology of inspiration and
expiration.
Occasionally, a longer inspiratory than
expiratory time is desired to allow more time to
oxygenate the patient’s lungs. This is called
inverse ratio ventilation.
Inspiratory:Expiratory (I:E) Ratio

47. The pressure limit regulates the amount of pressure
the VCV can generate to deliver the preset tidal volume.
Because high pressures can cause lung injury,
it’s recommended that the plateau pressure not exceed
35 cm H20.
If this limit is reached, the ventilator stops delivering the
breath and alarms.
This may be an indication that the patient’s airway is
obstructed with mucus. It can also be caused by the
patient coughing, biting on the ETT, breathing against
the ventilator, or by a kink in the ventilator tubing.
Pressure Limit

48. The flow rate is the speed with which the tidal volume is
delivered.
Flow Rate
The usual setting is 40-100 liters per minute.

49. The sensitivity determines the amount of effort
required by the patient to initiate inspiration.
Sensitivity/Trigger
It can be:
Pressure triggering 1 – 2 cm H2O
flow triggering. 1- 5 L/min
Flow triggering is a better setting for patients
who can breathe spontaneously because it
reduces the work of breathing.
time
pressure
trigger-
threshold

50. • Very fast rising
Depending on rise time, the beginning of the flow will be
• or slower
Rise time
For adults the range is
0-0.4 seconds

51. The ventilator can be programmed to deliver an
occasional sigh with a larger tidal volume. The use
of frequent sighs was popular during the 1970’s
because it was thought that it prevented collapse
of the alveoli (atelectasis), which can result from
the patient constantly inspiring the same volume
of gas.
However, recently there has been concern that
the increased pressure produced in the alveoli
may heighten the risk of the alveoli rupturing
and causing pneumothorax.
Sigh

52. Summary of initial ventilator set up
• A/C Mode
• Tidal volume depending on lung status
Normal lungs - 12 cc/kg ideal body weight
COPD - 10 cc/kg ideal body weight
ARDS - 6-8 cc/kg ideal body weight
• Rate of 10-12 breaths per minute
• FIO2 of 100%
• Sighs rarely needed
• PEEP only as indicated after first arterial blood gas
Shunt greater than 25%
Inability to oxygenate with safe FIO2

53. What is ASV?
Conventional
Tp
Rate
Psup
Pinsp
Ti
Te @
FiO2
PEEP
Vt
CMV
SIMV
PCV
PSV
Goal 3: Simple to use
Modes
Controls

54. What is ASV?
Conventional
Tp
Rate
Psup
Pinsp
Ti
Te @
FiO2
PEEP
Vt
CMV
SIMV
PCV
PSV
ASV
Goal 3: Simple to use
Controls

55. What is ASV?
Conventional
Tp
Rate
Psup
Pinsp
Ti
Te @
FiO2
PEEP
Vt
CMV
SIMV
PCV
PSV
ASV
Goal 3: Simple to use

56. What is ASV?
Conventional
Tp
Rate
Psup
Pinsp
Ti
Te @
FiO2
PEEP
Vt
CMV
SIMV
PCV
PSV
ASV
Goal 3: Simple to use

57. Tp
Rate Pinsp
Ti Te
PF
FiO2
PEEP
Vt
CMV
SIMV
PCV
PSV
Alveolar Ventilation Oxy.
Conventional
FiO2
PEEP
MV
Automatic
Mechanical ventilation

58. 2. MONITORS
Ventilators are designed to
monitor many components of
the patient’s respiratory status.

59. Patient monitoring

60. peak , mean , plateau and PEEP.
Pressure:

61. Vt, Vm, sigh volume.
Volume:
Frequency
(mandatory &
spontaneous).
MONITORS

62. I/E ratio It, Et.
FIO2.
MONITORS

63. Lung mechanics
Monitoring
Flow-time curve
Pressure-time curve
Volume-pressure loop
Flow-volume loop
Nigative
inspiratory
force (NIF)
AutoPEEP
Airway Resistance
Lung compliance

64. 3. Alarms
Help

65. 3. ALARMS
To ensure the safety and effectiveness of MV
electric or pneumatic alarms are installed on
ventilator to signal both visually and audibly
the presence of undesirable conditions.

67. Problem solving
• pCO2 too high !!!!!!!!!!!!!!
• pO2 too low !!!!!!!!!!!!!!!!!!!!!!!!!!
• PIP too high !!!!!!!!!!!!!!!!!!!!!!!
????????????????????????????????

68.  Safety considerations in mechanical ventilators
 Back up ventilation
 Low resistance non compliant breathing
circuit
 Limits on closed loop adjustments
 Reliable alarm system
 Battery for electrical failure

69. Golden rules in mechanical ventilation

70. 5- Adapt the ventilator to the patient instead of
adapting the patient to the ventilator.
2- A mode doesn’t make the lung healthy it
wins only time.
3- Keep healthy parts of the lung healthy.
4- Maintain and support spontaneous
breathing in ventilated patient.
1- Start the process of weaning the moment you
start mechanical ventilation.

71. 8- Avoid airway pressure more than 35
cmH2O
6- Employ tidal volume of 6 – 8 ml/kg Wt.
9- Don’t be too shy with PEEP.
10- Set always the trigger at the highest sensitivity
(avoid autocycling).
7- Give 7 – 8 cmH2O pressure support for
compensation of the tube resistance.
Vt PS PAP PEEP Triggering

72. pCO2 Too High
• Patient’s minute ventilation is too low.
• Increase rate or TV or both.
• If using PC ventilation, increase PIP.
• If PIP too high, increase the rate instead.
• If air-trapping is occurring, decrease the rate and the I-
time and increase the TV to allow complete exhalation.

73. pO2 Too Low
• Increase either the FiO2 or the mean airway
pressure (MAP).
• Try to avoid FiO2 >70%.
• Increasing the PEEP is the most efficient way
of increasing the MAP in the PICU.
• Can also increase the I-time to increase the
MAP (PC).
• Can increase the PIP in Pressure Control to
increase the MAP, but this generally doesn’t
add much at rates <30bpm.

74. PIP Too High
• Decrease the PIP (PC) or the TV (VC).
• Increase the I-time (VC).
• Change to another mode of ventilation. Generally,
pressure control achieves the same TV at a lower PIP
than volume control.
• If the high PIP is due to high airway resistance, generally
the lung is protected from barotrauma unless air-trapping
occurs.

75. Acute Deterioration
• DIFFERENTIAL DIAGNOSES
o Pneumothorax
o Right main stem intubation
o Pneumonia
o Pulmonary edema
o Airway occlusion
o Ventilator malfunction
o Mucus plugging
o Air leak
o hypoperfusion