The document discusses basic ventilator management, including the history and types of mechanical ventilation (negative and positive pressure). It outlines indications and exclusion criteria for non-invasive and invasive positive pressure ventilation, as well as guidelines for initial ventilator settings and monitoring. Additionally, it covers weaning procedures and potential complications associated with mechanical ventilation.

1. Basic Ventilator Management
Charipersion:
Assoc Prof Dr Md Mukhlesur Rahman
By
Dr Md Mashiul Alam
Phase B resident

2. Mechanical Ventilation: Short History
Negative pressure ventilation:
• The iron lung, also known as the Drinker and
Shaw tank, was developed in 1929
• Large scale use in 1940 during polio epidemic

5. Positive pressure ventilation:
by the military during World War II to supply
oxygen to fighter pilots in high altitude
In 1950 again during polio
epidemic

7. Types of mechanical Ventilation
• Negative pressure ventilation
• Positive pressure ventilation
- Noninvasive (NPPV)
- Invasive (IPPV)

8. IPPV vs NIPPV
• NPPV is the provision of any form of ventilatory
support applied without the use of an
endotracheal tube.
• With either a nasal or oral face mask.
• Patients can speak, eat and less chance of
pneumonia
Indication:
1. Acute exacerbation of COPD if the patient is alert
and no indication of ETT

9. 2. Patient with hypoxemic respiratory failure but
hemodynamically stable and can protect his or
her airway.
3. After extubation to avoid reintubation
4. Patient with acute pulmonary edema in the
absence of MI to redistribute fluid from
alveolar space to vessel.
5. Obstructive sleep apnea

10. Exclusion criteria for NPPV:
1. Patient is not breathing spontaneously
2. Hemodynamically instable
3. Un co-operative patient
4. Facial burns or other trauma
5. Copious secretion
6. High risk of aspiration

12. Invasive PPV
Indication:
1. Primary indication- impending or existing
respiratory failure despite maximal treatment
2. General anesthesia
3. Cardiogenic shock to decrease work of
breathing
4. Increased ICP

13. General parameters to consider MV:
• Respiratory rate > 30/min or less than 8 bpm
• Vital capacity <1-1.5 L/min
• PaO2 <60 mmHg on FIO2 > 0.5
• PaCO2 high with repiratory acidosis (pH<7.2)
• Exhaustion
• Confusion
• Severe shock
• Severe LVF
• Raised ICP

14. Basic Ventilator Settings

17. • FIO2: Fraction of inspired oxygen
concentration
Initially it should be 0.7 to 1 to ensure adequate
tissue oxygenation.
After an initial ABGA obtained FiO2 may be
decreased to 0.5 or less while achieving PO2
more than 60 mmHg to prevent oxygen
toxicity

18. • VT: Tidal Volume
A starting point for VT is 8 to 10 ml/Kg ideal body weight.
An acceptable VT is one that results in a plateau
pressure of 30 mmHg
A VT of 12 ml/Kg or more is not usually needed
• EVT: Exhaled Tidal Volume
Regardless of mode of ventilation the most accurate
measure of the volume received by the patient is the
exhaled tidal volume.
The volume actually received by the patient must be
confirmed by monitoring EVT on the display panel of
the ventilator

19. • RR: Respiratory Rate
Near physiological as possible: 10 to 20 bpm. Typical
initial rate settings are between 8 and 12 breaths/min.
Slow rate may be useful in patients with obstructive
pulmonary disease because as the rate is decreased
more time is available for exhalation
Fast rates may be useful in patients with noncomplaint
lungs to prevent barotrauma with small VT
RR x VT = minute ventilation (mV)
When patient has adequate respiratory drive no RR set on
the ventilator

20. • Flow Rate:
The speed with which the VT is delivered.
Average: 40-60L /min
High flow rate – Decreased inspiratory time
Increased peak inspiratory pressure (PIP)
Low flow rate – Increased inspiratory time
Decreased PIP

21. Pressure modes
Volume mode Spontaneous

23. • I:E (Inspiratory to expiratory ratio)
The duration of inspiration in comparison with
expiration.
Inspiratory time of 1 sec is a good initial setting.
Generally I:E ratio is set at 1:2
1:3 or 1:4 or longer may be necessary to ventilate
the lungs in COPD
I:E ratio is a function of flow rate, inspiratory time
and RR

24. Inversed I:E ratio:
1:1 or 2:1 or 3:1 are called inverse I:E ratio
Employed when conventional strategies to
improve oxygenation fail
But it may increase mean airway pressure
(mPaw) and lead to hemondynamic
compromise

25. • PEEP (Positive End Expiratory Pressure)
A constant positive pressure in the airways at
the end of expiration to prevent alveolar
collapse.
Range 5 to 10 cmH2O
5 to 10 cmH2O in LVF, 10 to 20 cmH2O in ARDS
It prevents atelectasis, improve oxygenation,
redistribute lung water from alveoli to
perivascular space

26. Initial ventilator settings: Guidelines
Parameter Initial settings
FiO2 0.7 – 1.0
Tidal Volume 8-12 ml/Kg, 4-6 ml/Kg is ARDS
RR 10-20
Flow rate 40-60 L /min
Inspiratory time 1 sec (.8 to 2 sec)
I:E ratio 1:2 to 1:3
Sensitivity Pressure trigger : -0.5 to -1.5 below
baseline. Flow trigger: 1 – 3 L/min
PEEP 3 -5 cmH20

27. Correcting oxygenation and ventilator
problems
Problem ABG findings Adjustments
Excessive oxygenation PaO2 >100
SaO2 100%
Decrease FiO2
Keep I:E to 1:2
Decreased PEEP
Inadequate oxygenation PaO2 <60
SaO2 <90%
Increase FiO2
Increase PEEP
Prolong inspiratory time to
increase mPaw
Respiratory acidosis PaCO2 >45
pH≤ 7.35
Increase VT with PIP ≤ 40
mmHg
Increase RR
Respiratory alkalosis PaCO2<35
pH ≥ 7.45
Decrease VT
Decrease RR

28. Modes of mechanical ventilation
• Breath types
Machine cycled:
1. Mandatory – Ventilator perform all of the
work of breathing
2. Assisted- breath is triggered by the patient
and then rest are taken over by the machine

29. • Patient cycled:
1. Supported breath – Triggered by patient and
cycled by patient. Ventilator helps a little.
2. Spontaneous breath – Patient performs all
the work of breathing

30. Ventilatory support
• Full ventilatory support (FVS):
CMV or A/CMV
1. Apnea
2. Paralysed
3. Severe flail chest
4. Depressed neurological state

31. • Partial Ventilatory Support (PVS):
It allows the patient to respond to increase in
CO2 and promotes use of respiratory muscle
thereby preventing disuse atrophy
SIMV, PSV, CPAP

32. Control Modes
1. Volume Control
2. Pressure Control
3. Dual control

33. Flow volume curve for Spontaneous
ventilation
expiration
Inpiration

34. Volume control ventilation
A delivered breath is volume controlled when
volume is constant for every breath. The
pressure wave form varies because is pressure
is variable.
Types:
• CMV
• A/CMV
• SIMV

35. CMV (continuous mandatory vent.)
Patient receives a preset number of breaths per
minute of a preset tidal volume (VT) and
patient’s effort does not trigger a mechanical
breath

37. • Indication:
1. No respiratory effort
2. Anesthesia
3. Backup to assisted ventilation

38. V A/CMV
Asisst/ Control Mandatory vent.
The ventilator delivers a preset number of
breaths of a preset VT and patient may trigger
spontaneous breath

39. Machine
triggered
Patient
triggered

40. • Indication:
1. Normal respiratory drive but patient is too
weak or unable to perform work of breathing
(WOB)
2. To allow patient to set their own rate

41. V SIMV
• Synchronized Intermittent Mandatory Vent.
Patient receives a set number of breaths of a set
VT but patient may initiate spontaneous
breaths un assisted by the ventilator.
Patients effort is assisted if it falls in mandatory
breathing window

42. Mandatory breathing
window

43. • Indication:
1. Normal respiratory drive by unable to
perform all WOB
2. Allowing patients to set their own RR and
assist in maintaining a normal PaCO2
3. Weaning from mechanical ventilation

44. Pressure control ventilation
A delivered breath is pressure controlled when
pressure is constant for every breath.
Here the pressure wave form has a specific pattern
for every breath while volume waveform varies.
Types:
• PC or P A/C
• PSV / P SIMV
• CPAP

45. P- A/CMV
A mode of ventilation in which every breath is
augmented by a preset amount of inspiratory
pressure and there is no set VT. It may sense
patients spontaneous breathing effort and assist
with preset pressure.
Indication:
Providing full ventilatory support (FVS) in patients
with non compliant lungs who exhibit high Paw
and poor oxygenation in volume control mode.

47. Advantage over volume control mode
1. Peak Inspiratory pressure (PIP) may be
reduced in – reducing chance of barotrauma.
2. Mean airway pressure (mPaw) is increased
which improves oxygenation
3. Limits excessive airway pressure as pressure
is set by the clinician
4. Lower WOB
5. Better gas distribuation

48. P-SIMV/ PSV
The patients spontaneous respiratory activity is
augmented by the delivery of a preset amount
of inspiratory positive pressure.
It may used alone or in combination of SIMV. In
P SIMV only the spontaneous breaths are
pressure supported

49. P SIMV

50. • Indication
1. Weaning from mechanical ventilation. PSV is
used for spontaneous breathing trial
2. Non invasive ventilation

51. Trouble shooting patient-ventilator
system
Objective:
1. To evaluate the patient’s response to the
current level of ventilatory support
2. To determine accuracy and appropriateness
of the current ventilatory settings
3. To ensure the presence and proper
functioning of the necessary equipment

52. Monitoring Patients
Patient should be assessed at least every 2 hours and with any
setting change
Medical history, current diagnosis and clinical course should
be known
Key components:
1. VITAL signs and hemodynamics
2. Physical examination – patient comfort, WOB, accessory
muscle use, symmetry of chest wall movement. Chest wall
examinaiton. Pulse. Airway leak. Swallow reflex. Abdominal
distension. Nutritional status.
3. Laboratory and Xray findings
4. Behaviors and complaints

53. Monitoring the ventilator
Key components:
Usually every 2 hours
Setting: Monitor information found on front
panel
Patient data: Monitor the information found on
the display panel
Alarms: Ensure all the alarms are activated and
appropriate alarm limits are set

55. Weaning procedure
When patient is on ventilator for more than 3
days weaning procedure become for complex
If the condition requiring ventilation is fully
corrected and the patient is alert and
breathing spontaneously – extubation is
planned

56. Weaning trial screen should be done daily
1. Hemaodynamically stable ( no arrythmia, HR
≤ 120 bpm, absence of vasopressores except
low dose dopamine and dobutamine
2. FiO2 ≤ 0.5
3. PEEP ≤ 8
4. Patient is on MV less than 3 days

57. Wean Trial Protocol
1. CPAP – one hour trial daily
If no sign of intolerance proceed to
extubation
if sign of intolerance – full resting mode
until next trial and at night
2. PSV – Max PSV level than decrease 5 cm H20 for
4 hours ---if no intolerance another 5 cm H20
decrease for another 4 hours. If intolerance defer
trial for the next day with FVS in between.

58. • Sign of intolerance ( any one 3-5 mins
sustained)
1. RR ≥ 35 breaths/ min
2. SpO2 ≤ 90% or decrease by 4 %
3. HR ≥ 140 bpm
4. SBP ≥ 180 or ≤ 90
5. Excessive anxiety or agitation
6. Diaphoresis

59. Complications of mechanical
ventilation
• Problems related to positive pressure
Ventilator induced lung injury – Barotrauma,
Oxygen toxicity
Reduction in cardiac output and oxygen delivery
Alteration in renal function and positive fluid
balance
Impaired hepatic function
Increased ICP
V/Q mismatch

60. • Problems related to the artificial airway
Infection (Ventilator associated pneumonia)
• Gastric distress
Abdominal distention
Ulcers and gastritis
• Patient’s anxiety and stress

61. Take Home message
• Put any acutely distressed patients on V
A/CMV at first and Sedate the patient if
needed
• Send ABG not less 20 mins of a change
• Adjust the ventilator according to ABG report,
SpO2
• Start weaning trial when the precipitating
condition resolved ( Use SIMV, PSV modes)

62. “After all there is no match for natural
ventilators…..”
THANK YOU