Mechanical Ventilation Flashcards
Name 4 reasons the airway is no longer protected and intubation may be indicated:
- Altered mental status
- Obstruction (angioedema/edema)
- Surgical intervention of naso/oropharynx
- Increased secretions requiring frequent auctioning
These three events are evidence of acute respiratory failure on an arterial blood gas and may indicate the need for intubation
- A pH of 7.25 or less with and elevated CO2
- A PaO2 of 60% with a patient on 60% fio2 or more
- A PaCO2 of >60 in a non CO2 retaining patient
Alterations in respiratory mechanics that may indicate the need for intubation are: (5)
- A spontaneous tidal volume of less than 5ml/kg of IBW
- A RR of >35 or 10
- A vital capacity of
What does a negative inspiratory force (NIF) that is low indicate?
That a patient is unable to draw in an adequate tidal volume
What causes an elevated minute ventilation?
A deep TV and breathing fast- can be caused by an obstructive lung disease or severe sepsis or kussmauls respiration so where they are attempting to breathe off acidosis
What are goals of intubation? (6)
- Airway protection
- Secretion managment
- PaO2- 60-100
- SpO2 > 90%
- FiO2
Signs of optimal ventilation are: (4)
- A PaCO2 of 35-45
- A pH of 7.35-7.45
- Acceptable airway pressures (peak pressure
What are two adjustments on the vent that improve oxygenation?
FiO2 and the PEep
What is peep?
Airway pressure in the lungs at end expiration
What is physiological peep
Less than or equal to 5
What are the two reasons to increase Peep above 5? (Not disease processes but what you are trying to do within the lungs)
- Restore functional residual capacity
2. Improve oxygenation without increasing FiO2 by stabilizing and recruiting alveoli and preventing further collapse
What is the functional residual capacity?
FRC- the amount of air in the lungs after a normal exhalation
Residual volume + expiration reserve volume
What are 4 complications of peep?
1- increased pressure in chest
2- decreased cardiac output
3- increased intrapulmonary shunting
4- barotrauma causing decreased lung compliance
How do we alter ventilation on a vent?
The minute ventilation or the respiratory rate x tidal volume
What are some other ways to improve ventilation on patients besides changing vent settings?
- Sedate and paralyze
- Treat fever
- High-fat and low carbohydrate nutrition (a byproduct of carbohydrate metabolizing is CO2 production)
- Decrease dead space ventilation by avoiding dehydration, exceeding peep, or ventilator tubing)
Explain the difference between pressure and volume-cycled ventilation
Pressure-cycled- a set pressure is delivered with mandatory breaths and the volume varies.
Volume cycled- a set volume is delivered with mandatory breaths and pressure varies
What is assist control ventilation?
This is the most common used volume-cycled ventilation. The patient receives a set volume at a set frequency or rate.
If the patient initiates a spontaneous breath, he receives the preset tidal volume
What are the strengths of AC mode ventilation?
- You get what you set
- Allows the patient to control the rate of breathing (above the set rate) while ensuring that every breath is supported
- Decreases WOB
What are the limitations of AC mode ventilation?
Can cause patient and ventilator dyssynchrony
Auto peep and barotrauma
Muscle atrophy
What is SIMV mode?
Volume ventilation with preset tidal volume similar to AC, however the patients spontaneous breaths will allow their own tidal volume with pressure support
What are the 3 strengths of SIMV mode ventilation?
- Widely used and understood mode of ventilation
- The patient performs a variable amount of work with security of preset mandatory ventilation
- Decreased iatrogenic respiratory alkalosis because the patient can set their own minute ventilation
What are the limitations of SIMV mode?
- Can increase WOB
- If rate too low the patient can fatigue
- Desynchronous at times
What is pressure support ventilation?
It is a patient-triggered mode with each spontaneous breath and gives pressure support
What are the strengths of pressure support ventilation
- Decreased WOB
- Patient sets own minute ventilation
- Weaning mode of ventilation
- Improved synchrony
- Useful in patients slow to wean
Limitations of PSV is what?
- It does not ensure a tidal volume or respiratory rate
2. Unstable patients should have a back-up up mandatory rate
CPAP mode supports the patient how?
Continuous airway pressure is maintained throughout the breathing cycle.
Used as a weaning mode where the patient is responsible for all phases of the respiratory cycle.
What is pressure control ventilation?
No preset tidal volume. Pressure is set to achieve a desired tidal volume with a set rate.
I:E ratio is controlled
Pressure control ventilation strengths are what?
- Peak airway pressures are controlled
- Peak pressures can be minimized while maintaining mean airway pressures
- Decrease in ventilator induced lung injury
Plateau pressure is what?
Plateau pressure represents peak alveolar pressure and is obtained during end-inspiratory breath hold.
How to you check compliance and plateau pressures in the lungs?
By performing an inspiratory hold maneuver to assess what the plateau pressure is
What is the peak inspiratory pressure?
The max amount of pressure in the lungs during a full inspiration
In an ARDS patient what should the TV be set to?
TV of 6ml/kg of IBW (less than usual)
What are some ventilator-induced lung injury causes from pressure control ventilation?
- Barotrauma- over expansion of alveoli due to high ventilation pressures
- Atelectrauma- shear stress induced injury caused by unstable alveoli recruiting and derecruiting
- Biotrauma- inflammatory injury that occurs due to the tissue damage caused by both volutrauma and atelactrauma
Why are vasopressors often needed more with pressure ventilation?
Increase pressure can cause cardiovascular compromise, necessitating increased use of vasopressors
What is APRV mode on a ventilator?
This is a mode of pressure ventilation good for patients with poor lung compliance. The patient is allowed spontaneous breaths at any point in the cycle
It has a pressure high and pressure low setting
Pressure high (plateau pressure) should be 20-30
Pressure low (peep) should be 5-10
Then there is the time high and low which is your inspiratory and exploratory times. Time high is time spent at pressure high and time low is time spent at pressure low
What are the strengths for APRV?
1 lower peak and plateau pressures
- Decrease use of sedation and paralytics
3 increase perfusion to dependent lung regions
- Increase cardiac output
- Increased functional residual capacity
- Can cause less cardiac compromise and decrease vasopressors use
What are the limitations of APRV mode?
- People don’t know how to use it
- MV must be monitored and is calculated differently
- Takes 8-16 hours to see benefit from this ventilator
- Not for patients with severe airflow obstruction
NIPPV has survival advantages for these types of patients in respiratory distress:
- COPD exacerbation
- CHF exacerbation
- Hypoxia respiratory failure associated with immunosuppressive state (Oncology and transplant patients)
- Hypoxia respiratory failure after major thoracic or abdominal surgery
What are parameters that indicate readiness for extubation?
- RR 15
6. FIO2
Systemic indications the patient is ready for extubation:
- Original reason the patient was intubated has resolved
- Good Abg and or SpO2
- Hemodynamic stability
- Free from continuous sedation
- No major fluid overload or electrolyte abnormality
What is an RSBI?
The rapid shallow breathing index takes the respiratory rate and the tidal volume and calculates it to determine if the extubation will be successful.
An RSBI of
How often and for how long should a SBT be attempted?
A SBT should be attempted once daily and should last 30minutes to 2 hours
What medication has been shown to be superior to other agents in reducing ventilator associated ICU days (sedation)
Propofol
What medication is associated with fewer ventilator days (sedation), experienced less delirium, tachycardia, and hypotension
Dexedetomidine (precedex)
When should you not perform a sedation holiday?
FIO2 > 60% Peep > 7.5 Increased ICP HR > 140 MI in the last 24 hrs ECMO On NMBA Active ETOH withdrawal