H. Arthur Sadhanandham

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Mechanical Ventilation

• H. Arthur Sadhanandham
• Medical ICU
• CMC, Vellore

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Primary Function

• To facilitate the movement of gas into the
  lungs.

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Goals

• To maintain adequate Oxygenation
• To maintain optimum Co2 elimination
• To reduce the load of work of breathing
• To regulate the rate of alveolar
• Ventilation

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Mechanical Ventilation
Non Invasive
Invasive
Non Invasive Ventilatory support that is given
without establishing endo- tracheal intubation or
tracheostomy is called Non invasive mechanical
ventilation Invasive Ventilatory support that is
given through endo-tracheal intubation or
tracheostomy is called as Invasive mechanical
ventilation
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Non invasive
Negative pressure Producing Neg. pressure
intermittently in the pleural space/ around the
thoracic cage
Positive pressure Delivering air/gas with
positive pressure to the airway
e.g. Iron Lung
BiPAP CPAP
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Invasive
Positive Pressure
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
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Conventional
Modes
Tp
Psup
Vt
Pinsp
Ti
Rate
Te
_at_
Controls
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Non Invasive
Invasive
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Continuous Positive Airway Pressure (CPAP)

• Given through air tight mask/ ET/ Tracheostomy
  tube
• Applies continuous positive pressure to the air
  way.
• Tidal volume and Resp. Rate are patient
  dependent.
• FiO2 PEEP are to be set in the equipment.

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Assist Controlled Ventilation (ACV)

• Delivers a preset tidal volume for every breath
  initiated by the machine
• Or triggered through the patients effort

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Controlled Mandatory Ventilation (CMV)

• Delivers a preset tidal volume / pressure at a
  preset rate, ignoring the patients own
  ventilatory effort.

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Intermittent Mandatory Ventilation (IMV)

• 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 patients own efforts.

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Synchronised intermittent Mandatory Ventilation
(SIMV)-

• Delivers a preset, mandatory tidal volume.
• Synchronised to the patients respiratory effort.

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SETTINGS
Power
O2 Air
Ventilator
Patient
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Initial Settings

• Mode SIMV with Pressure support (if available)
• 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 sec
• 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

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Remember that

• 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)

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Precaution Care

• Tracheobronchial Hygiene
• Placement of tube Chest movement
• Auscultation
• Post intubation X-ray
• Cuff pressure If insufficient- Leak
• Displacement of the tube
• Aspiration
• If high pressure - Tracheal stenosis
• Desired Pressure - 20-30cm water

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• Humidification Filling water adjusting
  temperature appropriately
• If inadequate secretions would become thicker
  and lead to tube block
• Medication
• Besides specific therapautic drugs the
• following basic drugs are to be given.
• Sedatives paralysing agents if needed.
• Analgesics
• Diuretics to reduce circulating fluid and volume
  overload
• Reduce Gastric Acid H2 blockers

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Suction

• Should be done on PRN basis
• Ascultate and assess
• View the chest X-ray
• Determine the need and for effective suctioning
• Hyperoxygenation ventilation ambu/normal
• Keep strict vigil on the cardiac monitor pulse
  oximeter during and soon after
  suctioning
• If necessary carry out effective chest physio

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• Monitoring
• 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 doctors order
• Sensorium
• Intake and output
• Level of comfort
• Arterial blood gases p r n or twice daily

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Nebulisation

• It is advisable to put all the patients on
  bronchodilators on regular basis.
• Nebulise as per the doctors order

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Injury during Mechanical Ventilation

• Possibility of ventilator associated lung injury,
  baro-trauma, tracheal necrosis etc have to be
  detected in time and take appropriate action.
• Use soft restrainers whenever necessary.

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Pain related to Mechanical ventilation ET tube
placement

• Positioning of the tube, pulling of the circuits,
  in appropriate flow rates, sensitivity setting
  that requires patients greater efforts, etc.
• Prevent all the above as much as possible.

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Eye Mouth care

• For unconscious patients eyes are kept closed by
  taping.
• Goggles can also be used.
• Regular proper mouth care should be given.
  

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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)

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Oxygen toxicity

• Try and maintain a SpO2 of gt 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.

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Nutrition

• Enteral nutrition to support the patients
  metabolic needs and defend against infection.
• Avoid high carbohydrate diet during weaning.
• NG tube if necessary relieves gastric
  distension and prevents aspiration.

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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.

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Alarms Positioning

• Never keep alarm system muted
• Never ignore even when you know the cause for the
  alarm and may not be fatal
• Place the patient in low or semi Fowlers
  position to improve comfort and facilitate
  respiration.

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Communication

• 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 and hopelessness
• Document patients emotional response and any
  signs of psychosis
• Include family in the care

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Teach

• Co-operation with medical and nursing
  interventions
• Certain breathing techniques
• The patient to recognize the importance of
  breathing techniques.
• Frequent assessment of consciousness level,
  adequate rest etc. are necessary.

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Weaning

• Assess for readiness to wean.
• Follow a clear cut protocol
• Provide emotional support and decrease the
  patients fear and anxiety
• Never try weaning at night
• If weaning once failed ( fatigue, sweating,
  dyspneic etc..) do not attempt for the next 24-48
  hours.
• Once weaning is successful, switch over to T
  piece
• Before extubation, do a leak test and cough test
  .
• if the above tests are positive -extubate by
  following proper protocol

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Minimum expectations from a Ventilator

• 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

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Contd

• Ability to deliver with variable inspiratory and
  expiratory ratio.
• Ability to maintain good humidification
• Ability to apply effective PEEP Pressure
  support.
• Ease of sterilization
• Quietness of Ventilator
• Effective Battery back up

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Sterilisation and decontamination

• After use, the patient circuit should be detached
  from the ventilator and disassembled to expose
  all surfaces prior to cleaning.
• 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.

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Contd

• 2 Glutaraldehyde is used for routine
  sterilisation of tubings and other accessories.
• Please follow manufacturers directions and
  recommendations.
• Ethylene Oxide gas sterilisation is also used.
  Ethylene oxide may cause superficial crazing of
  plastic components and will accelerate the aging
  of rubber components.

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Contd

• 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.

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Thank you