Ventilation Flashcards
What is the VC level of patients with neuromuscular disorders (e.g. Myasthenia Gravis) that indicates the need for mechanical ventilation?
10-15 cc/kg
True or false: mechanical ventilation can be a diagnostic tool
True
Normal spontaneous breathing is better at aerating what parts of the lung?
Posterior and inferior
What areas of the lung are commonly damaged with mechanical ventilation? Why?
- Anterior/superior
- Where gas accumulates when supine
What is the MOA of the iron lung? What is the major issue with this?
Decreases pressure surrounding chest
No diaphragm movement
What are the three T’s for volumes and pressure targets?
- Target volume/pressure
- Trigger (signal to initiate the breath)
- Termination
What are the two types of triggers for positive pressure ventilation?
Flow or pressure
What are mandatory breaths?
The guaranteed number of breaths that a ventilator will give no matter what
What is a controlled breath?
Breath initiated by the ventilator
What is an assisted breath?
Effort can initiate the breath, but ventilatory provides the pressure
What are the two characteristics of assisted breaths that the patient determines?
Initiation
Duration
The airway pressure is dependent on what two variables?
Ventilatory settings
Mechanics of lung and chest wall
What is the most common type of target for a ventilator?
Volume
What is the typical inspiratory flow rate?
30-80 L/min
What are the three patterns of delivery?
- Square wave
- Sine
- decelerating/ramp pattern
Vt with a ventilatory is determined by what?
Inspiration pressure and time
True or false: Vt is variable, and not guaranteed. Why or why not?
True–changes in lung mechanics can have significant impacts
What is the most common mode used for a ventilator? What is involved with this mode?
Assist control mode
Breaths are assisted with a either a volume or pressure target
What are the four variables that determine the frequency of ventilations?
- signals to initiate breaths
- Mode of ventilation
- Min set rate
- pt effort
What are the disadvantages of assist control mode?
- Respiratory Alkalosis
- Hyperinflation
How is VACV used as a diagnostic tool? (2)
- If pressures needed to get a given volume in are high, it may point to a restrictive lung disease
- If there is a large gap between park and plateau pressure, may point to bronchospasm
What is intermittent mandatory ventilation (IMV)?
Effort beyond set rate delivers spontaneous breath from a reservoir bag that contains gas with the same FiO2
What are the downsides of intermittent mandatory ventilation?
- Uncomfortable
- Inferior for weaning patients
What is spontaneous ventilation (PSV)?
Initiation and duration of breath are patient determined
What is the most comfortable mode for the alert patient?
PSV
What are the ways to improve oxygenation with a ventilator?
- Increase FiO2
- Adjust airway pressure of the ventilator
What is PEEP? What is the use of this?
Positive end expiratory pressure
Adding 5-20 cm H2O to keep alveoli open
What are the drawbacks to increased airway pressure? (3)
- Overdistention of the alveoli
- Decreases venous return
- Increased dead space from over distending functional alveoli
What determines the PCO2? What is the equation for this value?
Minute ventilation (=TVxRR)
What are the two variables of pressure control/assist?
RR
Pressure target
What are the two variables of volume cycled ventilation?
RR
TV
What is the optimal tidal volume for ARDS? Everyone else?
- ARDS = 4-6 cc/kg/IBW
- Everyone else= 6-8 cc/kg/IBW
What is the ideal body weight equation?
50 kg for 5 foot males
45 kg for 5 feet
2.3 kg for every inch above
Why are targeted tidal volumes important?
Prevent hyperinflation of the lung
What is the target of the plateau pressure?
Less than 30 cm H2O
What is the pH goal for ventilation?
Greater than 7.1
What is the TV goal for ventilation?
Less than 8 cc/kg/IBW
True or false: the longer someone is on the ventilator, the worse the survival
True
What are the three oxygen requirements for ventilator weaning (PEEP, FiO2, and PF values)?
- PEEP 5-8 cm H2O
- FiO2 less than 50%
- PF greater than 150
What is the cutoff for the rapid shallow breathing index for weaning?
f/VT less than 105
What fraction of extubations will fail?
1 in 5
Who usually fails extubation?
age greater than 65
What are the criteria for “difficult” extubation patient?
Fails 1-3 trials up to 7 days
What are the criteria for “prolonged” extubation patient?
Greater than 7 days
What is BiPAP?
Positive pressure through a mask
True or false: NIVs after extubation can help people get off of a ventilator
True
True or false AECOPD is appropriate for NIMV
True
True or false: comatose pts is appropriate for NIMV
False
True or false: Acute cardiogenic pulmonary edema is appropriate for NIMV
True
True or false: pts with excess secretions are appropriate for NIMV
False
True or false: pts with bleeding are appropriate for NIMV
False
True or false: pts with vomiting are appropriate for NIMV
False
True or false: pts with neuromuscular failure are appropriate for NIMV
True
True or false: pts with immunocompromised pneumonia are appropriate for NIMV
True
True or false: pts with hemodynamic instabilityare appropriate for NIMV
False
What are the benefits of NIV in AECOPD?
- Improves hospital mortality
- Decreased LOS
- Decreases risk of intubation
What is high flow nasal cannula oxygen?
Humidified air via NC
True or false: HFNCO is appropriate for shock
False
True or false: HFNCO is appropriate for hypercapnia
False
True or false: HFNCO is appropriate for Neuromuscular respiratory failure
False
True or false: HFNCO is appropriate for tachypnea
False
What are the three determinants of weaning off of a ventilator?
Pain
Agitation
Delirium
When is ECMO used?
-PaO2/FiO2 less than 150
What is the difference between ECMO and CBP?
- Closed chest cannulation
- Less anticoag
- Anesthetized, not sedated
