H. Arthur Sadhanandham
To facilitate the movement
of gas into the lungs.
To maintain adequate
To maintain optimum Co2
To reduce the load of work of
To regulate the rate of alveolar
Non Invasive Invasive
Non Invasive: Ventilatory support that is given without
establishing endo- tracheal intubation or
tracheostomy is called Non invasive mechanical
Invasive: Ventilatory support that is given through
endo-tracheal intubation or tracheostomy is called as
Invasive mechanical ventilation
Negative pressure Positive pressure
Producing Neg. pressure Delivering air/gas with
intermittently in the pleural positive pressure to the
space/ around the thoracic airway
e.g.: Iron Lung BiPAP & CPAP
Pressure cycle Volume cycle Time cycle
Pressure Cycle: A pre determined and preset pressure terminates
inspiration. Pressure is constant and volume is variable.
Volume Cycle: A pre determined and preset volume -on completion of its
delivery , terminates the inspiration. Pressure is variable
and volume is constant.
Time Cycle: Delivers air/gas over a set time (Insp. Time) after
which the inspiration ends.
Example: Pressure Controlled ventilation
CPAP Controlled Assist control Intermittent Synchronised
(CMV) ventilation Mandatory intermittant
(ACV) Ventilation mandatory
PCV ACV CMV
SIMV CPAP PSV
Psup Tp Vt
Rate Ti Pinsp
Continuous Positive Airway
Given through air tight mask/ ET/
Applies continuous positive pressure
to the air way.
Tidal volume and Resp. Rate are patient
FiO2 & PEEP are to be set in the
Assist Controlled Ventilation
• Delivers a preset tidal volume for
every breath initiated by the
• Or triggered through the patient’s
• Delivers a preset tidal volume /
pressure at a preset rate, ignoring the
patients own ventilatory effort.
• Delivers a preset tidal volume at a
preset rate while allowing the patient to
breathe at his own rate and tidal
volume in between.
• Can cause breath stacking – because
preset frequency of the machine may
not occur in the same phase as the
patient’s own efforts.
Mandatory Ventilation (SIMV):-
Delivers a preset, mandatory tidal
Synchronised to the patient’s
O2 Air Power
• Mode : SIMV with Pressure support (if
• FiO2 : 1.0 (100%)
• PEEP :5
• Tidal Volume : 6-7 ml / kg
• Rate : 10-15 / minute
• Pressure support : 15 cm H2O / If flow assist: 0.5
• Alarms : Max Pressure : 35 cm of H2O
: Min. pressure: 10 cm of H2O
Special consideration in the settings should be shown
to COPD and ARDS patients.
ABG – After one hour and adjust the settings
• PaO2 depends on FiO2 & PEEP
• PaCO2 depends on Tidal volume & Rate
In ICU, our primary aim is
• To get a PaO2 of 60-90 mmHg &
• PaCO2 of 30-50mmHg.
• Ensure that plateau inspiratory pressure
does not exceed 30cm of H2O ( risk of VALI –
Ventilator Associated Lung Injury)
Precaution & Care
• Tracheobronchial Hygiene:
• Placement of tube: Chest movement
Post intubation X-ray
• Cuff pressure: If insufficient- Leak
Displacement of the tube
If high pressure - Tracheal stenosis
Desired Pressure - 20-30cm water
Humidification Filling water & adjusting
temperature appropriately :
• If inadequate: secretions would become
thicker and lead to tube block
• Besides specific therapautic drugs the
following basic drugs are to be given.
• Sedatives & paralysing agents if needed.
• Diuretics to reduce circulating fluid and volume
• Reduce Gastric Acid: H2 blockers
• Should be done on PRN basis
• Ascultate and assess
• View the chest X-ray
• Determine the need and for effective
• Hyperoxygenation & ventilation –
• Keep strict vigil on the cardiac monitor pulse
oximeter during and soon after suctioning
• If necessary carry out effective chest physio
Continuous and Periodic monitoring of
• Vital parameters such as temperature,SpO2, Pulse,
BP,ECG pattern, breath rate etc.
• Ventilator settings: All settings should be
recorded – as per the
• Intake and output
• Level of comfort
• Arterial blood gases – p r n or twice daily
• It is advisable to put all the patients on
bronchodilators on regular basis.
• Nebulise as per the doctor’s order
Injury during Mechanical Ventilation
• Possibility of ventilator associated lung
injury, baro-trauma, tracheal necrosis
etc have to be detected in time and take
• Use soft restrainers whenever
Pain related to Mechanical
ventilation & ET tube placement
• Positioning of the tube, pulling of
the circuits, in appropriate flow
rates, sensitivity setting that
requires patient’s greater efforts,
• Prevent all the above as much as
Eye & Mouth care
• For unconscious patients
eyes are kept closed by
• Goggles can also be used.
• Regular & proper mouth
care should be given.
Monitoring for infection
• Colour, consistency, and amount of the
sputum / secretions with each
suctioning should be observed.
• Fever and other parameters have to
closely observed for any other
infection. (central line, etc)
• Try and maintain a SpO2 of > 90% and
PaO2 of 60 – 90 mmHg with minimum
possible FiO2 to prevent O2 toxicity.
• Especially for COPD patients :
Maintain SpO2 of 85 – 90% and PaO2
of 55 – 70 mmHg.
• Enteral nutrition to support the
patient’s metabolic needs and defend
• Avoid high carbohydrate diet during
NG tube if necessary – relieves gastric
distension and prevents aspiration.
Stress gastric ulcer
• Very common in critically ill patients
• Send stools for occult blood and
gastric juice for pH estimation
• Auscultate bowel movements
• Sedation and antacids adequately.
Alarms & Positioning:
• Never keep alarm system muted
• Never ignore even when you know the
cause for the alarm and may not be
• Place the patient in low or semi
Fowler’s position to improve comfort
and facilitate respiration.
• If conscious, explain the environment,
procedures, co-operation expected etc.
• Use verbal & non verbal methods
• Use paper & pen if necessary
• Provide calling bell if necessary
• Reassurance and support the patient
during the period of anxiety, frustration
• Document patient’s emotional
response and any signs of psychosis
• Include family in the care
• Co-operation with medical and nursing
• Certain breathing techniques
• The patient to recognize the importance
of breathing techniques.
• Frequent assessment of consciousness
level, adequate rest etc. are necessary.
• Assess for readiness to wean.
• Follow a clear cut protocol
• Provide emotional support and decrease the
patient’s fear and anxiety
• Never try weaning at night
• If weaning once failed ( fatigue, sweating,
dyspneic etc..) do not attempt for the next 24-
• Once weaning is successful, switch over to T
• Before extubation, do a leak test and cough
• if the above tests are positive -extubate by
following proper protocol
Minimum expectations from a
Ability to accurately deliver a tidal
volume from 20 ml to 1000 ml
Ability to deliver the set volume or the
set pressure against high resistance
and / or low compliance
Ability to deliver low flow rates
Ability to deliver at the rate ranging
from 2 – 60 /mt.
Ability to deliver set FiO2 accurately
Ensure it has a NIV mode
Ability to deliver with variable inspiratory and
Ability to maintain good humidification
Ability to apply effective PEEP & Pressure
Ease of sterilization
Quietness of Ventilator
Effective Battery back up
Sterilisation and decontamination
After use, the patient circuit should be
detached from the ventilator and
disassembled to expose all surfaces prior to
Thoroughly clean to remove all blood,
secretions, thick mucus and other residue.
You may use multi enzyme cleaner.
Medical detergent solution can also be used
to thoroughly to flush the tubings.
2% Glutaraldehyde is used for routine
sterilisation of tubings and other
Please follow manufacturer’s directions
Ethylene Oxide – gas sterilisation is also
used. Ethylene oxide may cause
superficial crazing of plastic components
and will accelerate the aging of rubber
Ensure complete dryness of the tubes before
sending for gas sterilisation as ethylene
glycol may be formed which is poisonous.
After sterilisation, the tubings must be
properly aerated to dissipate residual gas
absorbed by the materials.