This document provides an overview of mechanical ventilation. It discusses the history, indications, types, modes, and complications of mechanical ventilation. The main points are: - Mechanical ventilation delivers gas into the lungs through a ventilator to support patients who cannot breathe adequately on their own. - It has evolved significantly since the early uses of artificial respiration in biblical times and negative pressure ventilators in the 1800s-1900s. Positive pressure ventilation became widely used in the 1950s. - Indications include ventilatory failure, oxygenation failure, and conditions that could lead to respiratory failure like respiratory depression. - Modes include volume control, pressure control, and combinations like assist control ventilation,

1. Mechanical ventilation
By Dr Mengistu K(GSR II)
Moderator : Dr Gosa.T(Anesthesiologist)
June 2019 G.C
3/22/2021 1

2. OUTLINE
• Introduction About Mechanical Ventilation
• History
• Indications
• Types Of Mechanical Ventilation
• Modes of Mechanical Ventilation
• Alarm setting and troubleshooting
• Complications associated with Mechanical
Ventilation
3/22/2021 2

3. Introduction
• Mechanical ventilation is the process by which
the fraction of inspired oxygen (FIO2) is at
21%(room air) or greater and moved into and
out of the lungs by a mechanical ventilator.
• Mechanical Ventilation is ventilation of the
lungs by artificial means usually by a
ventilator.
• A ventilator delivers gas to the lungs with
either negative or positive pressure
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4. • Aim
– To maintain or improve ventilation, & tissue
oxygenation.
– To decrease the work of breathing & improve
patient’s comfort.
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5. History
• Historically, there is evidence of use of
artificial respiration since biblical times, use of
fire bellows in 15 century and negative
pressure ventilators in 1800s and early 1900s.
• Positive pressure ventilation as a clinical
modality was first used in 1950s at the
Massachusets General Hospital during the
polio epidemic in Europe and USA
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6. • Numerous advancements have led to the use
of highly sophisticated ventilators across a
wide range of patients making it a cornerstone
in the treatment of critically ill patients.
3/22/2021 6

7. Indications
• The indications may broadly be classified as
either ventilatory failure and oxygenation
failure.
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8. Ventilatory failure
• Inability of lungs to remove adequate CO2.
• Hypercapnia (increased PaCO2) and consequent
respiratory acidosis is the primary feature.
• Hypoxemia (low PaO2) may be secondary, but
responds well to supplemental oxygen.
• May be caused by various mechanisms like
– Hypoventilation
– Persistent V/Q mismatch
– Persistent intrapulmonary shunt
– Persistent diffusion defect
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9. Oxygenation failure
• Refers to hypoxemia not responsive to moderate
to high levels of supplemental oxygen.
• Caused by the same mechanisms as discussed
above, but more in severity.
• Hypoxemia refers to low oxygen content in blood.
PaO2 values of less than 60 mm Hg is moderate
hypoxemia, less the 40 mm hg is considered
severe hypoxemia. (Normal : 80-100 mm Hg)
• Hypoxia refers to reduced O2 in the organs and
tissues.
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10. Acute respiratory failure
• Primary ventilatory failure
– CNS depression: narcotics, sedatives and alcohol
– Neuromuscular disorders: poliomyelitis,
transverse myelitis, myasthenia, MND, GBS, spinal
trauma, snake bite, tetanus
– Comatose patients: Stroke and neurological
diseases, head injury etc. (GCS < 8, loss of gag
reflex,hypoventilation)
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11. • Acute pulmonary disease, eg. Fulminant
pneumonia, ARDS
• Fulminant pulmonary oedema
• Major pulmonary embolism
• Major atelectasis
• Acute exacerbation of COPD/
• Asthma non responsive to therapy
• Chest trauma: Flail chest, Pneumothorax,
Haemothorax
• Respiratory fatigue in critically ill
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12. Impending ventilatory failure
• Condition when the patient can maintain
marginally normal blood gases at the expense of
increased work of breathing.
– Acute airflow obstruction
– Rapidly progressive pulmonary parenchymal disease:
ARDS, pneumonia
– Cardiac conditions
– Shock of any etiology
– Drugs
– High risk postoperative patients (obese, upper-
abdominal/ thoracic surgery
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13. 3/22/2021 13

14. Therapeutic hyperventilation
• Conditions with raised ICP – head injury,
neurosurgery
• To reduce cerebral oedema after CVA
• Has been shown to be of benefit over only a
short period of time (24 hours), not instituted
within 8 hrs of injury
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15. Criteria for institution of ventilatory
support
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16. 3/22/2021 16

17. Terminology
• Independent variables :The parameters that
are set by clinician
• Dependent variables :The parameters
measured by the ventilators
• Four parameters can be controlled or
manipulated during each phases of
respiration: Volume, Pressure, Flow, Time.
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18. • Trigger variable
• Determines the start of inspiration.
• Time trigger:
– Breath is delivered once the preset time interval has elapsed.
– If RR is 12/min, the ventilator will deliver breath every 5 secs. (60s
/ 12 = 5), irrespective of patient effort or requirement.
• Pressure Trigger:
– Breath is delivered once preset negative pressure is generated by
patients’ spontaneous effort.
– Values of -1 to -5 cm of H20 (below end-expiratory pressure) is
acceptable.
• Flow Trigger:
– Breath is delivered when patients’ inspiratory flow reaches a
specific value.
– More sensitive than pressure trigger to detect inspiratory effort,
hence less inspiratory work.
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19. • Limit Variable:
– Normally, volume, pressure and flow all rise above
their baseline values during ventilator supported
breath.
– If one or more variable is not allowed to rise beyond
a preset value during inspiratory time, it is called limit
variable.
– Inspiration does not end at the preset value, but the
variable is held fixed at that value during inspiration.
• Cycle Variable:
– Inspiration ends when a specific cycle variable is
reached – pressure, volume, flow or time cycle)
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20. • Baseline Variable:
– Expiratory time = Interval between start of
expiration and start of inspiration.
– Variable that is controlled during expiratory time is
baseline variable; most commonly it is pressure.
– PEEP and CPAP are applied to the baseline
pressure variable.
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21. • Fraction of inspired oxygen (FiO2)
– The concentration of O in the inspired gas, usually
between 0.21 (room air) and 1.0 (100% )
• Tidal volume (Vt)
– The amount of air delivered to the patient per
breath. It is customarily expressed in milliliters. A
starting point for the V setting is 8 to 10ml/kg of
ideal weight
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22. • Respiratory rate/frequency (f)
– The number of breaths per minute. This can be
from the ventilator, the patient, or both.The RR is
set as near to physiological rates (14 to 20
breaths/min) as possible.
• Minute ventilation (V E)
– The product of V and respiratory frequency(VT•
f). It is usually expressed in liters/minute.
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23. • Exhaled Tidal Volume
– It is the amount of gas that comes out of the patients lungs on
exhalation.
– This is the most accurate measure of the volume received by the
patient
– If the EVT deviates from the set V by 50ml or more, troubleshoot
the system to identify the source of gas loss.
• Positive end-expiratory pressure (PEEP)
– The amount of positive pressure that is maintained at end-
expiration.
– Typical settings for PEEP are 5 to 20 cmH2O
– PEEP increases oxygenation by preventing collapse of small
airways It increases the functional residual capacity of the lungs
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24. • Inspiratory to Expiratory ratio
– The I:E ratio is usually set to mimic the pattern of
spontaneous ventilation.
– Generally the I:E ratio is set at 1:2, that is 33% of the
respiratory cycle is spent in inspiration and 66% in the
expiratory phase.
• Inverse Inspiratory to Expiratory ratio
– I:E ratios such as 1:1,2:1 and 3:1 are called inverse I:E
ratios
– Inverse I:E ratio allows unstable alveoli time to fill and
also prevents collapse by shortened expiratory phase.
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25. Auto PEEP
• Auto PEEP is the spontaneous development
of PEEP caused by gas trapping in the lung
resulting from insufficient expiratory time and
incomplete exhalation
• Causes of auto PEEP formation include rapid
RR, high VE demand, airflow obstruction and
inverse I:E ratio ventilation.
• Auto PEEP = Total PEEP - Set PEEP
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26. 3/22/2021 26

27. • 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
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28. • Peak airway pressure (Paw): The pressure
that is required to deliver the V to the
patient. It has a unit of centimeters of water
(cm H2O).
• Plateau pressure (Pplat): The pressure that is
needed to distend the lung. This pressure can
only be obtained by applying an end
inspiratory pause. It also has a unit of cm H2O
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29. • Mean airway pressure: The time-weighted
average pressure during the respiratory cycle.
It is expressed in cm H2O
• Peak inspiratory flow: The highest flow that is
used to deliver V to the patient during
inspiratory phase. It is usually measured in
liters/minute. Usual setting 40-80L/min.
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30. Types of mechanical ventilation
• Invasive ventilation or conventional
mechanical ventilation (MV) and noninvasive
ventilation (NIV)
• Positive or negative pressure ventilation
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31. Modes of ventilation
• The way the machine ventilates the patient
• How much the patient will participate in his
own ventilatory pattern.
• Each mode is different in determining how
much work of breathing the patient has to do.
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32. • Types of Positive-Pressure Ventilators
– Volume Ventilators.
– Pressure Ventilators
– High-Frequency Ventilators
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33. Modes of ventilation
• Volume control
– The ventilator delivers a pre set tidal volume.
– Pressures may vary with changes in resistance and
compliance, but volume remains constant.
– Volume may be measured by displacement of
piston or bellows, or by electronically computing
in relation to flow. ( Vol = Flow rate x Time)
– Inspiration ends when the pre set volume is
reached, or after certain time elapses (inspiratory
hold)
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34. • Volume modes
– Controlled Mandatory ventilation (CMV)
– Assist Control Ventilation(ACV)
– Intermittent Mandatory Ventilation(IMV)
– Synchronized Intermittent Mandatory
Ventilation(SIMV)
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35. Controlled mandatory ventilation
• Breaths are delivered at a set rate per minute
and a set tidal volume(vt) , which are
independent of the patient’s ventilatory
effects.
• Vt is delivered regardless of changes in lung
compliance or resistance.
• It is used when the patient has no drive to
breath or is unable to breath spontaneously
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36. • Indications:
– Initiation of MV, to
avoid dyssynchrony,
‘fighting’ or bucking.
– Extensive chest trauma
– Tetanus/ seizure
• Disadvantages:
– Regardless of effort,
patient cannot initiate
flow psychological
burden
– Due to sedation and
paralysis, potential for
apnea if accidental
disconnection
– Cannot be used for
weaning
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37. Assist Control Ventilation(ACV)
• A/C mode of ventilation delivers a preset number
of breaths of a preset Vt
• When the patient initiates a breath by exerting a
negative inspiratory effort, the ventilator delivers
an assisted breath of the preset VT
• The preset RR ensures that the patient receives
adequate ventilation, regardless of spontaneous
efforts
• The patient can breathe faster than the preset
rate but not slower.
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38. • Advantages:
– Very small WOB, if correct trigger sensitivity is set.
– Allows patient to control MV (through RR) to normalise PaCO2
• Disadvantages:
– Alveolar hyperventilation
– Respiratory alkalosis
– Higher pH and lower PaCO2 compared to IMV
• Contraindications:
– Irregular RR
– Cheyne – Stokes respiration
– Hiccoughs
– Brainstem injury
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39. 3/22/2021 39

40. Intermittent mandatory ventilation
• Allowed patient to breathe spontaneously between
controlled mandatory breaths.
• Advantages:
– More physiological control over MV and Paw
– Minimal cardio-vascular side effects of PPV
– Can be used during weaning.
• Disadvantages:
– ‘Breath Stacking’ – When mandatory breath delivered on
top of spontaneous breath, dangerous rise in Vt and Paw
– Partial WOB done by the patient
– High resistance during spontaneous breath through ETT.
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41. SIMV
• The SIMV mode of ventilation delivers a set
number of breaths of a set VT and between
these mandatory breaths the patient may
initiate spontaneous breaths.
• If the patient initiates a breath near the time
a mandatory breath is due, the delivery of the
mandatory breath is synchronized with the
patient’s spontaneous effort to prevent
patient ventilator dyssynchrony.
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42. • SIMV is indicated when it is desirable to allow
patients to breathe at their own RR and thus
assist in maintaining a normal PaCo2 or when
hyperventilation has occurred in the A/C mode.
• SIMV mode helps to prevent respiratory muscle
weakness associated with mechanical ventilation
• Self regulates the rate and volume of
spontaneous breath
• It is used as a mode for weaning
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43. 3/22/2021 43

44. • Pressure control
– Provides pre set pressure to the airways, not exceeding the
set level irrespective of changes in compliance and
resistance.
– VT is variable, dependent on compliance, Raw set pressure
and patient effort
– Once the preset pressure is achieved, a plateau is created
using ventilaor or patient generated flow.
– Expiration occurs once a pre set inspiratory time has
elapsed.
– PCV is thus time/patient triggered, pressure limited and
time cycled.
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45. • Pressure Modes
– Pressure-controlled ventilation (PCV)
– Pressure-support ventilation (PSV)
– Continuous positive airway pressure (CPAP)
– Positive end expiratory pressure (PEEP)
– Noninvasive bilevel positive airway pressure
ventilation (BiPAP)
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46. Pressure-controlled ventilation (PCV)
• Peak Inspiratory Pressure is predetermined, and the VT
delivered to the patient varies based on the selected
pressure and the compliance and resistance factors of
the patient –ventilator system.
• Patients with normal lung compliance and low
resistance will have better delivery of VT for the
amount of inspiratory pressure set.
• Advantage of pressure controlled modes is that the PIP
can be reliably controlled for each breath the ventilator
delivers.
• A disadvantage is that hypoventilation and respiratory
acidosis may occur since delivered VT varies
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47. Pressure-support ventilation (PSV)
• The patient’s spontaneous respiratory activity is
augmented by the delivery of a preset amount of
inspiratory positive pressure.
• The positive pressure is applied throughout inspiration
• There is no rate set on the ventilator the patient must
generate each breath
• Typical level of pressure support ordered for the
patient are 6 to 12 cm of H2O
• PSV may be used as a stand alone mode or in
combination with other modes
• • PSV may also be used for weaning from mechanical
ventilation
3/22/2021 47

48. Continuous positive airway pressure (CPAP)
• PEEP applied to spontaneous breathing
patient
• Requires eucapnic ventilation by the patient
• Can be applied via ETT, face mask, nasal mask
• In neonates nasal CPAP is method of choice
• Less adverse effects than PEEP because of
spontaneous rather than PPV
3/22/2021 48

49. Positive end expiratory pressure (PEEP)
• This is NOT a specific mode, but is rather an
adjunct to any of the vent modes.
• PEEP is the amount of pressure remaining in
the lung at the END of the expiratory phase.
• Utilized to keep otherwise collapsing lung
units open while hopefully also improving
oxygenation.
• Usually, 5-10 cmH2O
3/22/2021 49

50. Noninvasive bilevel positive airway pressure
ventilation (BiPAP)
• Independent positive pressures to inspiration
(IPAP) and expiration (EPAP)
• IPAP provides pressure support during
inspiration and EPAP helps in recruitment and
FRC
• Generally via non invasive methods, prevents
intubation in chronic diseases
• Initially IPAP – 8 cm H2O, EPAP – 4 cm H2O;
maybe increased or decreased in 2cm
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51. • A recruitment maneuver is a sustained
increase in airway pressure with the goal to
open collapsed alveoli, after which sufficient
PEEP is applied to keep the lungs open
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52. Ventilator alarms and troubleshooting
• Mechanical ventilators comprise audible and
visual alarm systems, which act as immediate
warning signals to altered ventilation.
• Alarm systems can be categorized according to
volume and pressure (high and low).
• High-pressure alarms warn of rising pressures.
• Low-pressure alarms warn of disconnection of
the patient from the ventilator or circuit leaks
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53. • High Minute Ventilation
– Set at 2 L/min or 10%-15% above baseline minute
ventilation
• Low Exhaled Tidal Volume Alarm
– Set 100 ml or 10%-15% lower than expired
mechanical tidal volume
• Causes: System leak, circuit disconnection and ET
tube cuff leak
• High Respiratory Rate Alarm
– Set 10 – 15 BPM over observed respiratory rate
3/22/2021 53

54. High Inspiratory Pressure Alarm
• Set 10 – 15 cm H2O above PIP
• Common causes:
– Water in circuit
– Kinking or biting of ET Tube
– Secretions in the airway
– Bronchospasm
– Tension pneumothorax
– Decrease in lung compliance
– Increase in airway resistance
– Coughing
3/22/2021 54

55. Low Inspiratory Pressure Alarm
• Set 10 – 15 cm H2O below observed PIP
• Causes
– System leak
– Circuit disconnection
– ET Tube cuff leak
 High/Low PEEP/CPAP Alarm (baseline alarm)
• High: Set 3-5 cm H2O above PEEP
– Circuit or exhalation manifold obstruction
– Auto – PEEP
• Low: Set 2-5 cm H2O below PEEP
– Circuit disconnect
3/22/2021 55

56. • High/Low FiO2 Alarm
– High: 5% over the analyzed FiO2
– Low: 5% below the analyzed FiO2
• High/Low Temperature Alarm
• Heated humidification
– High: No higher than 37oC
– Low: No lower than 30oC
3/22/2021 56

57. Apnea Alarm
– Set with a 15 – 20 second time delay
– In some ventilators, this triggers an apnea ventilation
mode
• Apnea Ventilation Settings
– Provide full ventilatory support if the patient become
apneic
• VT 8 – 12 mL/kg ideal body weight
• Rate 10 – 12 breaths/min
• FiO2 100%
3/22/2021 57

58. TROUBLESHOOTING
• If peak pressures are increasing:
– Check plateau pressures by allowing for an
inspiratory pause (this gives you the pressure in
the lung itself without the addition of resistance)
– If peak pressures are high and plateau pressures
are low then you have an obstruction
– If both peak pressures and plateau pressures are
high then you have a lung compliance issue
3/22/2021 58

59. • Increase in patient agitation and dis-synchrony
on the ventilator:
– Could be secondary to overall discomfort
• Increase sedation
– Could be secondary to feelings of air hunger
• Options include increasing tidal volume, increasing flow
rate, adjusting I:E ratio, increasing sedation
3/22/2021 59

60. • Complications of Mechanical Ventilation
3/22/2021 60

61. Complications of Mechanical
Ventilation
I-Airway Complications,
II- Mechanical complications,
III- Physiological Complications,
IV- Artificial Airway Complications.
3/22/2021 61

62. Airway Complications
– Aspiration
– Decreased clearance of secretions
– Nosocomial or ventilator-acquired pneumonia
3/22/2021 62

63. Mechanical complications
• Hypoventilation with atelectasis with respiratory acidosis or
hypoxemia.
• Hyperventilation with hypocapnia and respiratory alkalosis
• Barotrauma
– Closed pneumothorax
– Tension pneumothorax
– Pneumomediastinum
– Subcutaneous emphysema.
• Alarm “turned off”
• Failure of alarms or ventilator
• Inadequate nebulization or humidification
• Overheated inspired air, resulting in hyperthermia
3/22/2021 63

64. Physiological Complications
• Fluid overload with humidified air and sodium
chloride (NaCl) retention
• Depressed cardiac function and hypotension
• Stress ulcers
• Paralytic ileus
• Gastric distension
• Starvation
• Dyssynchronous breathing pattern
3/22/2021 64

65. Artificial Airway Complications
Complications related to endotracheal tube
– Tube kinked or plugged
– Tracheal stenosis or tracheomalacia
– Mainstem intubation with contralateral lung
atelectasis
– Cuff failure
– Sinusitis
– Otitis media
3/22/2021 65

66. Management of Mechanical
ventilation
3/22/2021 66

67. Strategies to improve ventilation
3/22/2021 67

68. Strategies to improve oxygenation
3/22/2021 68

69. Patient care during ongoing
mechanical ventilation
 Review communications
From patient to medical
staff and between doctors
and nurses
 Check and confirm
modes, settings and
alarms
 Airway management
 Assessment of sedation
and analgesic needs
 Meet the patient’s
nutritional needs
 Suction appropriately
 Assessment Infection
prevention
 Maintain hemodynamic
stability
 Check for possibility of
weaning
 Educate the patient and
the family
3/22/2021 69

70. Pain and analgesia
• Pain is a frequent symptom of mechanically ventilated
patient
• It may be due to intubation and ventilation itself, due to
disease conditions or due to movement and adjustment to
tubes and lines.
• Pain may be significant and can initiate elements of the
stress response
• Pain is reported by up to 60 % patients while on ventilator.
• Assessment of pain is dependent on the ability of patients’
to communicate
• The Numeric Rating Scale or Visual Analog Scale have been
validated
3/22/2021 70

71. • Assesment of pain is dependent on the ability
of patients’ to communicate
• The Neumeric Rating Scale or Visual Analog
Scale have been validated
• The Behavioral Pain Scale,Critical Care Pain
• Observation Tool and Non Verbal Pain Scale
are other tools that have been tested with
varying results
3/22/2021 71

72. Sedation
• Analgesia alone may be enough in some
patients, others may require additional
sedation
• Sedation reduces patient discomfort,
improves synchronicity and decreases O2
consumption and WOB
• But, also associated with delayed weaning,
hemodynamic liability and respiratory
depression
3/22/2021 72

73. • Intermittent boluses as well as continuous
infusion may be used.
• Infusions may have prolonged action after
discontinuation and accumulation of metabolites
• Daily ‘wake-up’ and assessment for weaning is
recommended.
• Numerous tools such as the Ramsay Sedation
Scale(RAS), Sedation Agitation Scale (SAS) and
Richmond Agitation Sedation Scale etc may be
employed
3/22/2021 73

74. 3/22/2021 74

75. Nutrition
• Protein Energy Malnutrition, common in critically ill
patients results in diminished strength and endurance.
• Weakness of respiratory muscles like diaphragm and
SCM lead to poor pulmonary performance, SOB, fatigue
and decreased response to hypoxia
• Malnutrition also affects the immune system, more
susceptibility to infection
• Low magnesium associated with muscle weakness,
hypophosphatemia – delayed weaning
• Recommended that nutritional therapy start latest by
3rd day of MV, within 24 hrs in malnourished patients
3/22/2021 75

76. 3/22/2021 76

77. Care of ventilator circuit
• Circuit compliance:
– Higher circuit compliance may result in lowe effective tidal
volumes
• Circuit Patency:
– Condensation of moisture from expired gases is the biggest
threat to patency
– Heated wire circuits, in-line water trap and HME filters are
commonly used for this purpose
• Frequency of circuit change:
– Frequent circuit change for infection control is not
recommended
– Some recommend circuit change only if visibly soiled
– Others have recommended weekly change of circuit
3/22/2021 77

78. • Patency of ET tubes:
– Secretions (low humidification)
– Kinking (patient positioning)
– Patient biting ETT
– Malfunction of ETT cuff
• HME Filters:
– Temporary humidification devices
– Placed between circuit and patient
– Absorbs heat and moisture during exahalation (CaCl2, AlCl2) and
transfers back during inspiration
– May colonise bacteria – anti-bacterial filter
– Large amount of secretions, very high MV and aerosol delivery
are potential problems
3/22/2021 78

79. Removal of secretions
• Repeated removal of secretions are necessary at times
• Pooled secretions may cause:
– Poor gas exchange
– Higher airway pressures
– Obstruction of ETT
– Patient coughing, restlessness
– Higher spontaneous RR
• Suctioning should be done when clinically necessary -
not routinely.
• The need for suctioning should be assessed at least
every 2hrs or more frequently as need arises
3/22/2021 79

80. • Combined with recruitment maneuvers and chest
physiotherapy
• Use of closed suction unit as far as practicable.
• Pre-oxygenation prior to suction procedure to
prevent desaturation
• Suction catheter should not occlude more than
50% of lumen of ETT
• Duration of suctioning limited to less than 15
seconds
3/22/2021 80

81. Weaning from mechanical ventilation
• Weaning is the process of withdrawal of
ventilatory support, ultimately resulting in a
patient breathing spontaneously and being
extubated.
• Transfer of WOB to the patient from the
ventilator.
• Weaning Success:
– Absence of need of ventilatory support 48 hrs
following extubation.
– The patient is able to pass a Spontaneous Breathing
Trial (SBT).
3/22/2021 81

82. Assessment of readiness to wean
General preconditions
• Reversal of primary problem
causing need for mechanical
ventilation
• Patient is awake and
responsive
• Good analgesia, ability to
cough
• No or minimal inotropic
support Ideally – functioning
bowels, abscense of distention
• Normalizing metabolic status
• Adequate Hb concentration
Objective values:
• Minute Ventilation <10l/min
• Vital Capacity > 10 ml/kg
• RR <35
• Tidal volume > 5ml/kg
• Max inspiratory pressure <-25
cm H2O
• RR /Vt <100 b/min/L
• PaCO2 < 50 mmHg
• PaO2 > 90 mm Hg at FiO2 0.4
• PaO2/ FiO2 > 200
3/22/2021 82

83. Methods of Weaning
• T-piece trial
• Continuous Positive Airway Pressure (CPAP)
weaning
• Synchronized Intermittent Mandatory
Ventilation (SIMV) weaning
• Pressure Support Ventilation (PSV) weaning.
3/22/2021 83

84. Weaning protocol
3/22/2021 84

85. • Termination of SBT
– RR > 30 for 5 min
– SpO2 < 90% for 30 sec
– 20% change in HR for > 5 min
– P SYS > 180 or < 90 for 1 min
– Anxiety, agitation or diaphoresis for 5 min
3/22/2021 85

86. Criteria for extubation failure
• fR >25 breaths/min for 2 hrs
• HR >140 beats/min or sustained increase or
decrease of > 20%
• Clinical signs of respiratory muscle fatigue or
increased work of breathing
• SpO2 < 90%; PaO2 <80 mmHg on FiO2 =0.50
• Hypercapnia (PaCO2 > 45 mmHg or = 20%
from preextubation), pH < 7.33
3/22/2021 86

87. • How to Wean Difficult to Wean Patients?
– Correction of Causes
– Choice of appropriate mode
– Tracheostomy Tracheostomy
Rehabilitation
Terminal care
Home
ventilation
Specialized
weaning unit
3/22/2021 87

88. Reference
3/22/2021 88

89. Thank you
3/22/2021 89