Midterm Flashcards
What is the angle of the needle when performing a ABG on the radial artery?
45 degrees
what is the angle of the needle when performing an ABG on the brachial artery?
60 degrees
What is the angle of the needle when performing an ABG on the femoral artery?
90 degrees
What is the guage of the needle when performing an ABG on the brachial artery?
20-22
What is the gauge of the needle when performing an ABG on the femoral artery?
20
What is the gauge of the needle when performing an ABG on a radial artery?
22-25
T/F: A 25 gauge needle is larger than a 14 gauge needle
False. As the gauge number increases, the size of the needle decreases
What are the primary reasons for drawing an ABG?
Ventilation
Oxygenation
Acid base balance
Disease severity
Therapy implications
What is the primary site chosen in adults and children for ABGs?
The radial artery
Why is the radial artery the first choice for an ABG?
The hand has collateral circulation due to the presence of the ulnar artery which will facilitate blood flow in the case where the radial artery is severely damaged
w do you assess a patient for collateral blood flow?
Modified allens test
Block radial and ulnar arteries for a few seconds while patient makes a fist and then release the ulnar artery. The palm should rapidly become pink
What would a negative result on the modified allens test look like?
the palm of the patient would remain blanched and not become pink after allowing flow through the ulnar artery
What are the most common hazards associated with ABGs?
Pain
Bleeding
Infection
Hematoma
What are common medications that prevent clotting?
Heparin
Warfin
Asperin
Xaralto
What laboratory results do we look at to associate a patients risk of bleeding?
Platelet count
Prothrombin time
Partial thromboplastin time
International normalized ratio
What is the normal range for prothrombin time?
13-15 seconds
Below what platelet count should you consult a physician regarding taking an ABG?
<50,000
What is the normal range for platelet counts?
150k-400k
What factors can negatively affect the accuracy of an ABG?
Air bubbles
Delayed analysis
Liquid heparin
What is the normal partial thromboplastin time?
22-29 sec
A prothrombin time of what would contraindicate drawing an ABG?
> 30 sec
A partial thromboplastin time of what would contraindicate drawing an ABG?
> 60 sec
What effect can air bubbles have on an ABG?
Increases pH
Decreases PaCO2
Moves PaO2 toward 150 mmHg
What effect can a delayed analysis have on an ABG?
Decrease in pH
Increase in PaCO2
Decrease in PaO2
hat effect can liquid heparin have on an ABG?
Decrease pH towards 7
Decreases PaCO2 toward 0
Moves PaO2 toward 150 mmHg
What are the primary pieces of clinically relevant information that can be gained from an ABG?
Partial pressure of oxygen
Partial pressure of CO2
pH
HCO3
What are the 2 primary assessment pieces of information gathered from an ABG?
Acid base balance
Oxygenation
What is the normal range for pH of human blood?
7.35-7.45
Describe the relationship between the partial pressure of CO2 and pH
Inverse
Increase in PaCO2 = decrease in pH
What is the normal level of HCO3 in the blood?
22-26 mEq/L
What is the relationship between HCO3 and pH?
Direct
Increase in HCO3 = Increase in pH
T/F: Oxygenation has no relation to pH
True
At what PaO2 is a patient considered mildly hypoxic?
60-80
At what PaO2 is a patient considered moderately hypoxic?
40-59
At what PaO2 is a patient considered severely hypoxic?
<40
What are the steps for ABG interpretation?
Assess pH
Assess PaCO2
Assess HCO3-
Do the arrow thing. Opposite = Respiratory, Same = Metabolic
Oxygen assessment
Describe full compensation
Full compensation is when the pH has returned to a normal level due to changes in respiration of bicarbonate levels
What are the benefits of an A-line?
Easy access for blood sampling
Continuous monitoring of arterial blood pressure
Describe partial compensation
The buffering organ is outside of its normal range, but pH is still not quite normal
Describe what a mode is on a ventilator
A set of instructions that tells a ventilator how to deliver a breath
Describe what a trigger is
A trigger is a qualifying event that the ventilator identifies as a signal to deliver a breath
What are the 5 ways a breath can be triggered?
Time
Manually
Pressure
Flow
Electric activity of the diaphragm
How does a patient trigger a breath with pressure?
Patient inhalation causes a pressure drop in the circuit resulting in a breath being triggered
ow does a patient trigger a breath with flow?
Patient sips some flow away from bias flow in the circuit
I have no fucking idea what this means
Describe what happens after a breath is triggered
Expiratory valve closes
Pressure/flow are introduced into the circuit
Circuit is pressurized
Lungs expand
Describe what a cycle is in terms of breath delivery
A cycle is the end of the DELIVERY of a breath, not the end of a total cycle of breath
What can cause cycling of a breath?
Time
Volume
Flow
Violation of a rule
What are the components of total cycle time?
I-time
E-time
What are the 5 basic ventilator settings?
target
PEEP
Rate
FiO2
What capacity is preserved by PEEP?
FRC
How is PEEP maintained on the ventilator?
The exhalation valve preserves a preset level of pressure once the flow of exhalation has been released
The vent circuit still carries some level of flow after exhalation even though a new breath is not being delivered
How does cardiac output change during negative pressure inspiration and positive pressure inspiration? Why?
The cardiac output during negative pressure inspiration will be greater because the negative pressure generated by the movement of the chest away from the lungs will result in a negative intrapulmonary pressure which will result in the vessels and chambers of the heart being pulled on slightly and expanded allowing for more blood flow. The opposite occurs during positive pressure inspiration where gas is forced into the lungs resulting in positive pressure being applied to the heart and vessels restricting flow and compromising cardiac output
Describe what happens to intrapleural pressure during inspiration and expiration with an unassisted breath
At base level there is a negative pressure in the intrapleural space due to the elastic recoil of the lungs inward and the chest wall outward. During inspiration, the chest wall moves outward pulling on the intrapleural space creating an increase in negative pressure. As the breath is released, the chest wall recoils inward resulting in a decrease in the negative pressure experienced in the pleural space
Describe what happens to intrapulmonary pressure during unassisted breathing
during inspiration, intrapulmonary pressure drops as the lungs are pulled outwards by the expansion of the chest wall, however at the end of inspiration the pressure has returned to zero. During expiration, the intrapulmonary pressure climbs above zero briefly due to the elastic recoil of the lungs and chest wall pushing on the pulmonary vessels briefly. The pressure elevates to 5 cmH20 briefly but returns to zero
Describe what happens to the pleural pressure during a positive pressure breath
During a positive pressure breath, the pleural pressure goes from being negative (which is where it is normally) to being positive
Describe how gas is distributed during a positive pressure breath when a patient is supine and why
region of the lungs and decreased perfusion towards the ventral region of the lungs. During a positive pressure breath, the positive pressure will open the portion of the lungs with the greatest compliance which are the portions in the ventral region. These portions are less perfused than the dorsal portions which will result in a VQ mismatch
What is the definition of transairway pressure?
The pressure required to produced airflow in the airways or
The pressure pressure required to overcome the resistance of the airway
What is the formula for transairway pressure?
PIP-Plat
What is the definition of transthoracic pressure?
The pressure required to expand or contract the lungs and the chest wall at the same time
What is the formula for transthoracic pressure
Plat-PEEP
What is trans respiratory pressure?
The pressure applied to the airway opening by a ventilator, BiPAP or BVM to expand the lungs and chest
What is the formula for transrespiratory pressure?
Transrespiratory pressure = transthoracic pressure + transairway pressure
What disease processes result in low compliance?
ILD
Pneumonia
pleural effusion
What is an assisted breath?
A breath is assisted if the ventilator provides some or all of the work of breathing
What is a mandatory breath?
A breath that is shaped by the machine outside of the patients control which is following the modes instructions
What does PC-CMV stand for?
Pressure control - continuous mandatory ventilation
What is a spontaneous breath?
A breath shaped by some degree by the patient
Patient triggered
Flow cycled
What is the control variable when using PC-CMV?
Pressure
What cycles the breath when using PC-CMV?
Time
What triggers the breath when using PC-CMV?
Time
Patient trigger
What is the control variable when using PC-CMV on adults?
Pressure delivered over PEEP (for adults)
What is the control variable for PC-CMV for peds?
Total PIP = PEEP plus added pressure
Describe the generic flow wave in a PC-CMV breath
Flow is front loaded
Flow is then responsive rather than fixed to maintain the pressure set by the RT
What does the pressure wave look like on PC-CMV?
Flat topped, indicates that once target pressure is reached it is held for the total Itime and then released when the breath is cycled via time
what determines and can affect tidal volume when using PC-CMV?
Pressure determines tidal volume
Can be affected by patient condition such as airway resistance or increased/decreased elastance
What are the ordered settings for PC-CMV?
PC
Rate
PEEP
FiO2
Itime (maybe)
What additional settings do you have to work with when using PC-CMV?
Itime
Rise time
Patient trigger
What is rise time?
Rise time is the time it takes for a pressure control breath to reach the pressure set in the mode parameters.
In what ways can Itime be set?
Seconds (milliseconds) (most frequent)
As a percentage of total cycle time
I/E ratio
What are other names for rise time because vent manufacturers are massive cucks who cant agree on one god damn naming convention?
Rise time
Pramp
Pressure rise
Inspiratory rise time
How can a patient trigger a breath when using PC-CMV?
Flow
Pressure
Electrical activity of the diaphragm
Why is it important to properly configure trigger sensitivity for a patient on mechanical ventilation?
If the trigger sensitivity is too high, the machine will deliver excess breaths
If the trigger sensitivity is too low, the machine will miss patient efforts
Describe the relative difficulty for a patient to trigger a breath on PC-CMV in regards to flow and pressure
Flow is easier for the patient to trigger a breath
Pressure is more difficult for a patient to trigger a breath
What is the control variable for VC-CMV?
Volume
What are the triggers for breaths with a patient on VC-CMV?
Time
Patient trigger
What cycles a breath in VC-CMV?
Volume
What are the settings generally ordered for a patient on VC-CMV?
Tidal volume
Rate
PEEP
FiO2
Itime (maybe)
Describe the appearance of the scalars in VC-CMV
The pressure scalar looks like a lean to with a straight roof
Flow can look like a box, however it is generally adjusted to look like a lean-to which puts more flow up front to mimic normal breathing
Volume looks like a shark fin but the forward section is a little straighter
Describe flow patterns in regard to VC-CMV
Flow is predetermined, however the delivery of the flow can be modified to either deliver constant flow (square top) or more flow up front to mimic PC-CMV flows which are more natural.
What are other settings that can be considered while using VC-CMV?
Flow wave type
Itime
Inspiratory pause
What does the vent calculate when the RT sets the Itime on the vent when in VC-CMV?
The vent calculates how much predetermined flow will be needed to meet the target Vt at the end of the Itime
When the target Vt has been met, the breath will then be cycled
What is the point of an inspiratory pause when using VC-CMV?
A zero flow state is needed to determine plateau pressure which cannot be measured if there is flow in the system
How long does an inspiratory pause need to be in order to read a plateau pressure?
As little as 0.5 seconds
Can a plateau pressure be measured when using a vent on PC-CMV?
Traditionally no. The vent will maintain the target pressure which will require some degree of flow however some vents are able to circumvent this…somehow. But mostly no. i think…
hat are the characteristics of a mandatory breath?
Ventilator controls the timing, tidal volume or inspiratory pressure
The machine triggers and cycles the breath
Note that mandatory breaths are assisted breaths
Can a patient trigger a mandatory breath?
Yes, but the vent will deliver a machine breath in CMV modes
What are the characteristics of a spontaneous breath?
Patient controls the timing and the tidal volume of the breath
Volume and/or pressure is not set by the operator but rather the patients demand and lung characteristics
What controls the volume and/or pressure during a spontaneous breath?
The patients demand and lung characteristics
T/F: a patient cannot trigger a manual breath
False, a patient can trigger a mandatory breath but will have no control over the breath delivered
T/F: when a patient is in a spontaneous breathing mode, pressure support is not offered by the ventilator
False. Pressure support may be offered by the vent at different levels by differing means
What is PC-CSV?
Pressure controlled continuous spontaneous ventilation
When using a vent in PC-CSV what triggers a breath?
The patient
What do the flow waves show in PC-CSV?
The amount of pressure support the patient is receiving
How is volume determined in PC-CSV?
Patient effort
What are other names for PC-CSV?
CPAP
CPAP with pressure support
Pressure support ventilation
SPONT
What are the ordered settings for PC-CSV?
PEEP
FiO2
Psupport
What are additional settings for PC-CSV?
Patient trigger
Rise time
PS flow cycle
Describe how flow is cycled in PC-CSV
By adjusting expiratory flow trigger sensitivity
Flow support (breath delivery) will stop at the selected flow rate
Selected flow rate is a percentage of peak flow (75%, 50%, 25%)
What is the relationship between the selected flow percentage and Itime when using a PC-CSV mode?
The higher the percentage is, the shorter the Itime will be
What happens if a patient fails to breath on PC-CSV?
A back up mode kicks in. If patient resumes spontaneous breathing, most vents will resume CSV
What is the main difference between PC-CMV and PC-CSV?
Both are instructed to reach a target pressure
Delivery in both modes is guided by rise time
BUT in PC-CSV, the patient does not have to endure a breath that is timed to be too long or too short like they might if they were in PC-CMV. They cycle the breath by changing their flow rate
What happens when a patient starts to exhale when they are on PC-CSV?
Inspiratory flow declines and the vent lets go of delivery
What happens if the vent develops a leak in the circuit?
Automatic tubing compensation or Tubing resistance compensation
Outside of OSA, when is CPAP used?
Noninvasive ventilation of patient with oxygenation problems or heart failure
Sometimes used for spontaneous breathing trials for extubation readiness
Describe IMV
Intermittent mandatory ventilation
Delivers mandatory and spontaneous breaths based on patient effort and desired rate
What are the ordered settings for PC-IMV?
Pressure
Rate
PEEP
FiO2
Itime
Pressure support
Patient trigger
Rise time
PS flow cycle
Patient effort within the trigger window is met with what kind of breath when using PC-IMV?
Spontaneous breath
How does the vent know when to deliver a breath and what kind of breath to deliver when using PC-IMV?
The mode algorithm maintains a trigger window
Patient effort within the trigger window is met with a spontaneous breath
Patient effort within the synchronization window is met with what?
A mandatory breath that counts as the rate breath
What have IMV modes historically been used for?
Weaning patients off the vent
What are the ordered settings for VC-IMV?
Tidal volume
Rate
PEEP
FiO2
Itime
Pressure support
Patient trigger
Rise time
PS flow cycle
What is a risk associated with the vent delivering too much pressure?
Barotrauma
List some alarms that would qualify as life threatening, high priority alarms that are GUARANTEED to go off right as you are about to go on lunch
Power failure
Electronic failure
Exhalation valve failure
High or low pressure from gas source
List some alarms that would qualify as life threatening, but medium priority and definitely correlated to go off when you’re about to go on a bathroom break after 6 hours
Circuit leak
Circuit occlusion
FiO2 blender failure
High or low PEEP
Humidification failure
List some non-life threatening alarms that will go off about 50 million times every shift slowly draining what is left of your sanity, your humanity, and your will to live leaving you a dried up husk of human (aka Zeke)
High or low minute ventilation
High or low tidal volume
High or low PIP
autoPEEP
What are some reasons why the high pressure alarm goes off?
Patient coughs
Secretions
Mucous plug
Patient-vent asynchrony
Where should you set the high pressure alarm
10-15 cm H2O above acceptable PIP
What are some reasons the low pressure alarm might go off?
Disconnection
Leak
Malfunctioning PEEP valve
Suctioning
What should you generally set the low pressure alarm to?
8 cm H2O
5-10 cm H2O below PIP
Why might a patient have a high minute ventilation?
Discomfort
Asynchrony
Anxiety
Pain
Waking up from anesthesia
What are some reasons a patient might be tachypneic that arent comfort related?
Neurologic conditions
Fever
Elevated metabolism
Metabolic acidosis
DKA
OVERLY SENSITIVE TRIGGER SETTING
What should the high minute ventilation alarm be set to?
10-15% above baseline minute ventilation
Why might a patient have a low minute ventilation?
Sedation
Neurologic problems
Low metabolic rate
Hypothermia
What should the low minute ventilation alarm be set to?
10-15% below guaranteed minute ventilation
Consider PBW
Why might the high tidal volume alarm go off?
Discomfort
Changes in patient condition
PC or PS set too high
Breath stacking
Why might the low tidal volume alarm go off?
Sedation
Neuro problems
Low metabolic rate
Changes in patient condition
What should the low tidal volume alarm be set to?
10-15% below set tidal volume or target tidal volume
What is the standard apnea alarm for adults?
20 seconds
What is the primary and secondary control variable when using PRVC?
Primary: Pressure with adaptable targeting
Secondary: volume with setpoint targeting
What is the trigger for patients on PRVC?
Time
Patient trigger
What cycles the breath when using PRVC?
Time
What are the ordered settings when using PRVC?
Rate
PEEP
FiO2
Itime
Patient trigger
Rise time
How does the vent determine what pressure to deliver in PRVC?
By adjusting pressure until the breath meets the target value
Breath larger than target = less pressure
Breath smaller than target = more pressure
What are the ordered settings for PRVC IMV?
Tidal volume
Rate
PEEP
FiO2
Itime
Pressure support
What are the ordered settings for APRV?
P-high
P-low
T-high
T-low
FiO2
What are the benefits of PRVC
Guarantees Vt and Ve like VC-CMV
Provides flow up front like PC-CMV
Decreases patient asynchrony
What are the settings for PR-VC IMV
Target Vt
Rate
PEEP
FiO2
Itime
Pressure support
Patient trigger
Rise time
PS Flow Cycle
What are the ordered settings for PR-VC IMV
Target Vt
Rate
PEEP
FiO2
Itime
Pressure support
What is APRV?
Airway pressure release ventilation
What are the possible settings for APRV?
P-high
P-low
T-high
T-low
FiO2
Patient trigger
Rise time
What are the ordered settings for APRV?
P-high
P-low
T-high
T-low
FiO2
PC-CMV and VC-CMV have a lot of the same settings. What settings do the two modes not have in common?
VC-CMV - Flow wave type and Inspiratory pause
PC-CMV - Rise Time and Patient trigger
What ordered settings are shared between PC-CMV and VC-CMV?
Rate
PEEP
FiO2
Itime
Which modes do not have a Rate as part of their ordered settings?
PC-CSV
APRV
Which mode incorporates an inspiratory pause into its main settings?
VC-CMV
Which modes incorporate a pressure support flow cycle?
PC-CSV
PC-IMV
VC-IMV
PRVC-IMV
What mode does not directly incorporate a PEEP setting?
APRV
PEEP might still be measurable or be able to be set, but not directly. Will find out
Which modes incorporate a pressure support setting?
PC-CSV
PC-IMV
VC-IMV
PRVC IMV
Which modes do not incorporate and Itime setting?
PC-CSV
APRV
A breath is defined as what?
A breath is one cycle of positive flow (inspiration) and negative flow (expiration) defined in terms of the flow time curve
Describe in basic terms what constitutes an assisted breath
A breath is assisted if the ventilator provides some or all of the work of breathing
What are the three basic breath sequences?
Continuous mandatory ventilation (CMV)
Intermittent mandatory ventilation (IMV)
Continuous spontaneous ventilation (CSV)
What are the 5 basic ventilatory patterns?
VC-CMV
VC-IMV
PC-CMV
PC-IMV
PC-CSV
PRVC-PS (not sure what this is, check book)
How are modes of ventilation classified?
Modes of ventilation are classified according to their control variable, breath sequence, and targeting scheme(s)
What does it mean if a patient is on full ventilatory support?
The vent is providing 100% of patients ventilatory needs
What are the advantages of having a patient on full ventilatory support?
Minimizes or eliminates patients work of breathing
Allows for ventilatory muscle rest and recovery from ventilatory muscle dysfunction
What does it mean if a vent mode has assist control?
Assist control means the patient triggers the vent to give a breath
What kind of breath will a patient receive if they trigger a breath in CMV?
They will receive the exact same breath as they would if it was a mandatory breath
What triggers a PC-CMV breath?
Time or patient
What is the target in PC-CMV?
Pressure
What cycles the breath in PC-CMV?
Time
What determines the tidal volume in PC-CMV?
The Pressure Control or Inspiratory Pressure Limit
What effect will decreased compliance have on the breath received by a patient on a PC-CMV mode? Why?
If a patients compliance decreases and the pressure setting remains the same, their tidal volume will decrease as the pressure required to reach the desirable tidal volume will be greater than what the vent is set to meet
What will happen to a patients tidal volume if their compliance increases due to their condition improving?
Their tidal volume will increase and the pressure setting on the vent will have to be decreased accordingly to ensure that the lungs are not being over inflated due to the increased compliance
What can happen to tidal volume if Itime is increased in PC-CMV?
The tidal volume may increase as a result of increased Itime due to the pressure being placed on the lungs for a longer period of time allowing for more alveoli to be recruited
What are the advantages of PC-CMV?
Provides full ventilatory support
Allows for ventilatory muscle rest and recovery
Inspiratory pressure remains constant when changes in compliance and resistance are met
Desired tidal volume can be achieved by adjusting pressure control level or Itime
What are disadvantages to PC-CMV?
Tidal volume varies when changes in patient effort, system compliance or airway resistance are present
No guaranteed minimum minute ventilation because tidal volume may vary
What happens if PEEP is increased and PIP remains the same for a patient on a vc-cmvvent on PC-CMV?
The delta P will decrease resulting in a decrease in delivered tidal volume
Why is it important to consider trigger sensitivity when adjusting settings on the vent?
Improper trigger sensitivity could result in the delivery of erroneous breaths or inadvertently increase the patients work of breathing when they are trying to get a breath but cant
What can happen if an inadequate Etime is set on the ventilator?
autoPEEP may develop
Air trapping
What triggers a breath for a patient on VC-CMV?
Patient trigger
Time trigger
How is a breath cycled with VC-CMV?
Volume
Time