Mechanical Ventilator Control: Guidelines for adjustment , Mechanical Ventilator Settings

Ventilator Control: Guidelines for adjustment
–    Manipulation of airway pressure is an effective approach to:
–    Improving pulmonary gas exchange in acute respiratory failure.
–    Time relationship between inspiratory and expiratoy phases (I: E ratio).
–    Respiratory rate (RR), Tidal Volume (Vt), and oxygen concentration of inspired oxygen.
–    All impact significantly on alveolar ventilation, and thus gas exchange and can be manipulated to derive optimal benefit for the patient.
–    Before setting up the machine, a total clinical assessment must be performed to identify indicators for mechanical ventilation and to establish data.
–    The patient ventilatory capacity, ABGs values, and laboratory data, together with clinical history and physical examination, all aid in decision making process.
Ventilator Settings
»    FiO2: Fraction of inspired oxygen
»    Respiratory rate
»    Tidal volume
»    Minute Volume
»    Peak flow
»    Pressure limit
»    Sigh
»    Sensitivity

Fraction of inspired oxygen (Fio2):
–     adjusted to achieve PaO2 more than 60 mmHg them do ABGs
–    change by ABG and O2 saturation
Respiratory Rate:
–    the frequency of breaths delivered by the ventilator
–    start with a rate that is somewhat normal; i.e., 10-16 breath/m for  adolescent/child, 20-30 breath/m for infant/small child.


Tidal Volume (VT)
–    Amount of gas delivered with each preset breath
–    Maximum volume/pressure to achieve good ventilation and  oxygenation without producing alveolar overdistention
–    In mechanically ventilated patients it’s usually set at 10 ml/kg, “Traditionally 10-12 ml/kg”
Minute Volume VE
–    Minute volume = RR X Tidal volume.
Ventilatory Mode
–    Is SIMV better than CMC, AMV? No, use mode your comfortable with patient
Inspiratory: Expiratory Ratio (I : E Ratio)
–    usually set at 1 : 2,  may be manipulated to facilitate gas exchange.
–    used to determine the patient’s effort to initiate an assisted breath (inspiration)
–    may be included as part of the ventilator settings.
–    a breath that has a greater volume than the preset VT , usually 1.5 to 2.0 times the VT
–    The usual sigh rate is established at frequency of 5-10 minutes intervals.
Peak Inspiratory Pressure (PIP)
–    Peak pressure registered in the airway during normal ventilation.
–    Value used to set high and low pressure alarm limits.
Pressure Limits
–    High pressure limit is the maximum pressure the ventilator can generate to deliver the preset VT
–    Usually set 10 – 20 cm H2O above the PIP
Which parameters need to be adjusted to improve oxygenation?
–     Increasing the FiO2
–     Increasing the level of the PEEP
–     Increasing the I:E ratio
Which parameters need to be adjusted to improve ventilation?
–    Ventilation (the ability to ‘blow off ’CO2) may be improved by
–     Increasing the respiratory rate
–     Increasing the tidal volume
–     Increasing the peak pressure
Airway Placement
–    Intubation
–    Refers to the insertion of an artificial airway, an endotracheal tube (ETT) into the trachea through the mouth or nose
–    Equipment Needed for Intubation
–    Laryngoscope & blade
–    Suction / suction catheters
–    Syringe to inflate cuff (10 cc)
–    Topical anesthetic & sedation as ordered
–    Water soluble lubricant,  Tape or device to secure tube
–    Stethoscope,  Manual Resuscitation Bag (Ambu)
–    O2 flow meter
–    Assisting with Intubation
–    Intubation is performed by anesthesiologists, nurse anesthetists, some paramedics, and MDs.
–    Check cuff and laryngoscope prior to insertion
–    Administer sedation/neuromuscular blockade as ordered
–    Prepare patient: remove dentures,  and suction if indicated
–    After intubation: Auscultate breath sounds bilaterally, inflate cuff,  secure tube, connect to ventilator or oxygen source
–    Order CXR to confirm placement
–    Insert NGT  to prevent aspiration
–    Record  position of tube at lips (cm)
–    Change sides of mouth q 24 hours
–    May need to insert oral airway to prevent biting of tube.

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