Today our topic of discussion is Ventilator Setting Up.
Ventilator Setting Up
VENTILATOR SETTING UP
Airway has to be established either by endotracheal tube of tracheostomy tube before connecting. The patient to the mechanical ventilator setting up may vary depending on the type of ventilator used, its features and settings, setting up of a volume ventilator is given below.
A volume-controlled ventilator (MAT, Bear Servo) will deliver set tidal volume with varying pressures. Variables which control ventilation and oxygenation are:
- Tidal volume: Set by tidal volume knob measured as inhaled volume. The normal tidal volume of a spontaneously breathing patient is 5-6m/kg.
- While setting up one seeks to deliver 10-15 mL/kg of ideal body weight Ventilator rate adjusted by rate knob, 8-10/minute.
- Adjusted depending on blood gas analysis Fraction-inspired oxygen concentration (FiO): Is set on ventilator or with an oxygen blender and measured with an O, analyzer.
- FiO, may be set at 100% initially and reduced depending on PaO, level which should be kept above 60 mm of Hg .
- Sensitivity setting: Increased sensitivity indications that very low negative pressure is required to trigger the machine
- Type of ventilation: Controlled or Assist/control/MV/ SIMV/PEEP> (Set with in the ventilator with the use of external devices).
- Routinely 5 cm PEEP is added for adult patient. Exact levels are adjusted for individual patient.
- Ventilator dead space: Circuit common to inhalation and exhalation. Tubing is calibrated
- CO, elimination: Controlled by tidal volume, rate and dead space
- Oxygen tension: Controlled by O, concentration and PEEP
- Inspiratory flour rate and inspiratory expiratory ratio:Depending on the type of ventilator employed there are different ways to determine the inspiratory and expiratory times.
- In some they are set in seconds- normal being 0.5-1.5 seconds. The 1:E ratio is 1:2-1:3 Minute volume = tidal volumex rate/mm, normal about 6-8 liters/mm
- Airway pressure: Normal 15-20 cm/H,O Low airway pressure is seen with air leak.
- High airway pressure is seen increased secretions, airway obstruction, bronchospasm, edema, pneumothorax, flail chest, patient out of phase with ventilator.
- Sigh: The lungs are hyperinflated periodically to open collapsed alveoli. The sigh is given by machine or manual hand bag ventilation.
- Sigh volume is 2 times tidal volume every 5-10 minutes.
- Humidification: It helps to prevent atelectasis and secondary infection.
- Bubble diffusion humidifiers provide molecules of water and saturate the inspired gas to 100% humidity.
- Alarm systems: The ventilator is equipped with alarms to ensure safety, oxygen alarms, high and low pressure alarms; apnea alarms are all included in an ideal ventilator.
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