Mechanical Ventilation Flashcards
What is the goal of mechanical ventilation?
- to give supportive respiratory therapy
- Support and improve ventilation and perfusion
- Bridge to recovery or until decision of EOL
- Non curative
What is mechanical ventilation?
oxygen is moved in and out of the lung by mechanical means. It requires a endotracheal tube or a tracheostomy
What are the two types of mechanical ventilation?
Negative pressure ventilation
Positive pressure ventilation
Examples of positive pressure ventilation
- Volume ventilation or pressure ventilation
2. PEEP and CPAP (NIVVP)
Indications for mechanical ventilation are?
- Apnea
- Unprotected airway
- Acute Respiratory Failure
- Acute Respiratory Distress Syndrome (ARDS)
- Severe Hypoxemia
- Severe Respiratory Muscle fatigue/impairment
What are some examples of severe respiratory muscle fatigue/impairment?
COPD or spinal cord injury (C5, C7)
When are PEEP and CPAP commonly used?
when the patient is over sedated or can’t protect their ariway
When is volume ventilation or pressure ventilation used?
when the patient cannot breath on their own
Data related reason to ventilate
- CO2 more than 50
- O2 less than 50
- RR ineffective, more than 40
- RR less than 8
- pH 7.3 or less
Others: diminished or absent breath sounds, swallow expansion, ARDS, respiratory muscle fatigue
What is a ventilator mode?
the way that inspiration/expiration are provide or set
How do you select the ventilator mode?
- based on the patient’s individual status
2. ABG, LOC, respiratory drive, therapeutic needs
How recommend the mode?
RT and RN
What considerations do you need to incorporate when setting up. a ventilator?
- Patient weight (ideal weight for height even if skinny or overweight)
- LOC
- Patients response
6 components of ventilator settings are?
- FiO2
- Rate: frequency of breaths per minute
- Tidal volume
- Positive end-expiratory pressure
- Sensitivity
- Max pressure limits
What is tidal volume?
how much air that the patient will get with each breath
What is normal tidal volume?
MV tidal volume? ARDS tidal volume?
Normal: 5mL/kg
MV: 6-8 mL/kg
ARDS: 4-8 mL/kg
What is permissive hypercapnia?
pCO2 of 50-70mmhg
May be allowed to avoid barotrauma
What is PEEP (positive end-expiratory pressure)?
The pressure in the lungs above atmospheric pressure that exists at the end of expiration that can be kept to maintain airway patency
Keeps positive pressure on the lungs at the end of respiration cycle to keep alevoli open
Vent setting: sensitivity
amount of effort from a patient that is required to innate a breath
What happens if the max pressure limit is met?
The ventilation will release any excess pressure to avoid barotrauma
What is the usual pressure limit on MV?
10-20 cm H2O above peak inspiratory pressure
What is the goal PaO2 for a patient of MV?
above 60
The way negative ventilation works
- A device chamber surrounds the outside of the chest with negative pressure
- Chest is pulled outward and air enter the lungs
- Expiration is negative
Examples of negative ventilation
Iron lung or cuirass
Adevantages/disadvantages to negative pressure ventilation
Advantage: no artificial airway and can be done at home
Disadvantage: volume per breath can’t really be measured, uncontrolled therapy and skin damage
What patients is negative pressure ventilation commonly used for? Not used for?
Used for neuromuscular disorders like MS or MD
NOT used for critical care
How does positive pressure mechanical ventilation work?
- Positive pressure is applied to the airways at inspiration
- Intrathoracic pressure increased with inspiration as the ventilator sends measured tidal volume or breath in - this stays positive until breath ends
When is positive pressure ventilation is applied to the airways and is their expiration active or passive?
applied on inspiration and their expiration is passive
What are the two volume modes and are they used often?
- Assist control
- Synchronized intermittent mandatory ventilation (SIMV)
These are rarely used
What are the three pressure modes? Why are they more commonly used?
- Pressure support ventilation
- PEEP
- CPAP
More commonly used, safe and effective
How does assist control work?
Tidal volumes and number of breaths are set
Patient can initiate their own breaths which the set tidal volume will be given and the machine will still give the set breaths per minute
Pros and cons of assist control
Pros:
- Decrease WOB
- Some independence
Cons:
1. Hypo or hyperventilation if settings are too slow or too fast
What is the purpose of PEEP?
to make sure that the alveoli do not collapse
What is SIMV (synchronized intermittent mandatory ventilation)?
A set number of breaths with a set volume
Patient is able to breath on their own with their own volume
When is the SIMV breath delivered?
At the end of the expiration so patient is comfortable
What are the uses of SIMV?
- Weaning - allows improved synchrony between patent and ventilator
- More comfort for patient
- Used in. combo with pressure support for wean
Pros and cons for SIMV
Pros
1. Decrease positive pressure breath
Improve CO
Cons:
- Hypoventilation if rate is too low and patient is not taking own breaths
- Close monitoring
- Rate too low –> paitinet become fatigued and acidotic
Is SIMV used very often?
Not with newer ventilators, might find use of this on rehab units
What is pressure control ventilation (PCV) mode?
Set rate but tidal volumes are not set
Amount of pressure needed to provide rate is controlled
What is pressure control inverse ration?
combines pressure controlled ventilation with inverse ratio of inspiration and expiration
Normal RR is: 1:2 or 1:3
IVR is 1:1
What is IVR used in?
ARDS
What are the pros of airway pressure release ventilation (APRV)?
- Allows for release of pressure so if pt takes a giant breath then it won’t add more pressure if not needed, it will just release it
- Pt. can take a breath and the ventilator allows
- Less PPV
- Used for patients who need high pressure to open and recruit alveoli
- Decreases need for deep sedation