– 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.
» FiO2: Fraction of inspired oxygen
» Respiratory rate
» Tidal volume
» Minute Volume
» Peak flow
» Pressure limit
Fraction of inspired oxygen (Fio2):
– adjusted to achieve PaO2 more than 60 mmHg them do ABGs
– change by ABG and O2 saturation
– 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.
– CMV, IMV, SIMV, A/C, PCV
– 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.
– 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
– VENTILATOR ALARMS MUST NEVER BE IGNORED OR DISARMED!!!!
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
– 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.