module 2 quiz Flashcards
What are the main types of flow patterns?
Constant = square
Decelerating
Ascending
Sine
What is the equation for determining what FiO2 you should put a patient on who is receiving mechanical ventilation?
Desired FiO2 = Desired PaO2 x Known FiO2 / Known PaO2
What are the risks associated with high FiO2s?
Oxygen toxicity
Absorption atelectasis
Describe absorption atelectasis
Nitrogen is washed out of the alveoli by excess oxygen, oxygen dissolves into the blood resulting in a low partial pressure in the alveoli causing atelectasis
What is extrinsic PEEP?
Level of PEEP set on the ventilator
What is intrinsic PEEP?
Amount of pressure in the lungs at the end of exhalation
What is total PEEP?
Extrinsic PEEP + Intrinsic PEEP
A pulse oximeter reading of 90% indicates a PaO2 of what?
At least 60 mmHg
What are the functions of PEEP?
maintain/restore FRC
Enhance tissue oxygenation
Recruit alveoli and maintain them in an aerated state
What is the minimum level of PEEP set on most patients?
2-6 cm H2O
PEEP usually set to 5
When is PEEP considered therapeutic?
When it is greater than 5 cm H2O
When considering patient oxygenation, when should you increase FiO2 and when should you increase PEEP?
Patient with a low PaO2 on less than 60% = increase FiO2
Patient with a low PaO2 on more than 60% = PEEP
When performing a vent check, what should you check on the vent and in the room as part of the routine check?
Alarm settings
External alarm connection
Air and oxygen connections
Power supply
Resuscitation bag and mask
Suction
ETT secure
What are the two options for humidifying air on a ventilator?
Heat moisture exchangers
Heated humidifiers
What is a normal range for triggering a breath using pressure on a ventilator?
-0.5 to -2.0 cm H2O
How is a breath triggered with flow?
Ventilator has bias flow which is the amount of flow available in the circuit and can recognize when there is an absence of flow due to patient effort
What is auto PEEP and when does it occur?
Auto PEEP is air trapping
Occurs in patients with a prolonged expiratory phase
What effect can a leak in the circuit have?
A leak in the circuit will cause a pressure change which can result in false or auto triggering of breaths
What issues can auto PEEP create?
Will make triggering a breath more difficult for the patient
Where is rise time found?
Only found in pressure breaths
PCV
CSV
PRVC
BiPAP
What is rise time?
The time in which airway pressure builds to the maximum pressure value set
What are the benefits of a longer Itime?
Larger tidal volume
More lung recruitment
Increased mean airway pressure
What are the cons for longer Itime?
Shorter time for exhalation can lead to air trapping
Not comfortable for patient
What is the relationship between flow and Itime?
Faster the flow = shorter the Itime
Slower the flow = longer the Itime
What is a closed loop mode?
Vent takes information it receives from the patients and alters how it delivers the breath
What factors can affect PIP?
Itime
Tidal volume
Flow
Compliance and resistance of patient lungs
What is an open loop mode?
Mode delivers a breath based on the information entered by the RT and does not respond to input from the patient
Define a set point targeting scheme
RT instructs the ventilator to deliver a certain breath, the vent delivers a breath as it was instructed
What are examples of modes with set point targeting schemes?
PC-CMV
AC-CMV
Define an adaptive targeting scheme
The delivered breath is monitored and the delivery of the next breath will be influenced by the previous breath
Define an optimal targeting scheme
Uses an algorithm to determine the best way to deliver breaths based off the patient
What are examples of modes with adaptive targeting schemes?
PRVC
What are the disadvantages of setpoint targeting?
High PIPs
Low tidal volumes
Vigilant monitoring with lots of adjustments
What are the clinical advantages of adaptive targeting?
Patient comfort
Fewer adjustments
What are the clinical advantages or PC-CMV and AC-CMV?
Guaranteed volumes
Guaranteed pressures
What are the clinical disadvantages of PRVC?
Works against and inappropriately chosen patient
What are the clinical disadvantages of PC-CMV and AC-CMV?
High PIPS
Low tidal volumes
Lots of monitoring and adjustment
What are the clinical advantages of adaptive PRVC?
Patient comfort
Few adjustments
What are the settings for VC-MMV?
Vt
RR
PEEP
FiO2
Itime
PS
Flow cycle sensitivity
What does the operator set on VC-MMV?
Operator sets a CMV volume and rate to meet a target minute ventilation
Which manufacturer uses VC-MMV?
Drager
If a patient triggers a breath on VC-MMV what will the mode do?
Deliver a pressure support breath according to the set level of pressure support
How are breaths delivered on VC-MMV?
If the patient meets the minimum minute ventilation target, all breaths will be spontaneous
If the patient does not meet the minimum minute ventilation target, mandatory breaths will be given
What are the targets set for VC-MMV?
Primary = Volume
Secondary = pressure
T/F: Mandatory breaths are not synchronized with patient effort in VC-MMV
False. In VC-MMV mandatory breaths are synchronized with patient effort
Describe a situation where VC-MMV would be appropriate to use
A patient is sedated and paralyzed. At first the patient is giving no effort because of paralyzation and the vent delivers completely mandatory breaths to meet the set minimum minute ventilation set. As the paralytic wears off, the patient will begin to give spontaneous efforts that will be pressure supported, but not enough to meet MMV so mandatory breaths will continue to be delivered in addition to spontaneously triggered breaths. When the paralytic completely wears off, the patient will be able to trigger and breath more independently resulting in mandatory breaths being reduced as spontaneous supported breaths take over
What does automode do?
Provides seamless shifting back and forth between mandatory and spontaneous breaths in response to patient conditions
What is automode found on?
Getinge
How is automode dissimilar to MMV?
It doesnt target a MV
How is automode dissimilar to IMV?
Automode drops mandatory breaths
What kind of breaths does automode deliver?
Mandatory and spontaneous
How does automode determine whether or not to deliver a mandatory or spontaneous breath?
If the patient is triggering breath at a rate greater than the set rate, all breaths will be spontaneous
If the patient is triggering breaths at a rate less than the set rate, some breaths will be spontaneous, others will be mandatory
What is ASV found on? What does it mean?
Hamilton vents
Adaptive support ventilation
How does ASV achieve its target?
ASV achieves it target minute ventilation by using an algorithm to tritrate rate and tidal volume to meet minute ventilation target
What is the target of ASV?
Minute ventilation
T/F: In ASV, the operator sets the pressure control level
False.
T/F: In ASV, the operator does not set the pressure support level
True
What default does ASV target for minute ventilation?
100 mL/Kg of IBW
Example, 70 kg patient would get 7.0 L/m as MV target
What is a safety frame in an ASV mode?
A safety frame defines acceptable combinations of rate and volume
How does the vent decide what kind of breath to deliver in ASV?
Patient effort = pressure supported breath
Responds to low minute ventilation with mandatory pressure controlled breaths
What factors does the ASV algorithm determine?
Determines mandatory rate
Determines pressure to achieve Vt
Determines inspiratory time
Determines start up breath pattern
what is the “A” variable on the safety frame in ASV?
Pressure
What are the ordered settings for ASV?
Ideal body weigh
% minute ventilation
PEEP
FiO2
Pramp
ETS
Patient trigger
What are the axes present on the ASV graph?
Y axis = volume
X axis = RR
What are the clinical advantages of optimal targeting?
Is a very comfortable mode for the patient
Can potentially be used from intubation to extubation
Adapts to changing conditions
What pieces of information are related by the safety frame on the ASV graph?
A = pressure
B = tidal volume
C = frequency
D = low rate
What types of patients would not be a good fit for ASV?
Patients with restrictive lung diseases
Patients in hypercapnic respiratory failure since rates cant be adjusted manually
Post cardiothoracic surgery patients
How does volume support provide only spontaneous breaths yet reach set tidal volume?
Volume support acts like PRVC in that it provides a titrated pressure support in order to reach a goal tidal volume
What is automatic tubing compensation?
A setting that allows you to increase inspiratory pressure to overcome the resistance of an artificial airway
How does an operator set up automatic tubing compensation?
Find setting
Enter tubing type, diameter, and length of airway
What support does automatic tubing compensation offer to a patient who is spontaneously breathing with no other support?
Helps patient overcome airway resistance provided by the artificial airway
Theres not really any good evidence that it helps and just adds to complicating the targeting scheme
What are the steps smartcare and intellivent use to move the patient throught the weaning process?
Stabilize
Wean
Challenge
Describe the AI ventilation used by dragers smart care and hamiltons intellivent
Essentially offers automated patient weaning by using AI to determine the acceptable ranges of frequency of spontaneous breathing, tidal volume, EtCO2
Titrates pressure support to keep patient in an acceptable zone
What concerns do clinicians have regarding smartcare and intellivent?
Relies on SpO2 and EtCO2 which can be spotty at best with their accuracy due to patient movement or medications the patient may be on such as blood pressure medication
What is the formula for dynamic compliance?
Cdyn = VT / PIP-PEEP
What is the formula for static compliance?
Cstat = VT / PIP-Plat
What is the formula for airway resistance?
Raw = PIP-Plat / Flow (Liters per second)
What factors can affect a patients PaO2 when they are being mechanically ventilated?
FiO2
MAP
Lung Function
I:E time
PEEP
What factors affect mean airway pressure
PIP
PEEP
I:E ratio
RR
What is normal airway resistance in non-intubated healthy people?
0.6-2.4 cmH2O/L/sec
What is normal airway resistance in healthy intubated people?
5-12 cmH2O/L/sec
T/F: Airway obstructions can lead to autoPEEP
True
What are the main causes of autoPEEP?
Obstructive diseases
Bad vent settings
