CFRN MAIN EXAMINATION 2026 SET QUESTIONS AND
SOLUTIONS RATED A+
✔✔Exhaled tidal volume (Vte) - ✔✔Most accurate measurement of volume received by
pt.
Should be within +/- 50 of set Vt.
Only available in volume setting on ventilator.
✔✔Trigger - ✔✔AKA sensitivity
Set range from low to high with the lower number representing an easier amount of
force to initiate breath; the higher the number, the more effort to trigger breath.
✔✔Pressure trigger - ✔✔Pt has to draw in certain amount of pressure (usually -2 or -3)
to trigger a breath. Based on mode, it will either deliver the breath or allow pt the ability
to take a spontaneous breath.
✔✔Peak Pressure (PIP) - ✔✔Only used in volume controlled ventilation.
Measurement of pressure at upper airway, ETT, vent circuit, bronchial tree.
Always the highest pressure on vent.
✔✔Peak Inspiratory Pressure (PIP)
Normal value - ✔✔Keep <40 cm H2O
✔✔Peak Inspiratory Pressure (PIP)
Things that affect value - ✔✔- Overall volume going down airway
- How fast volume is going in
- Compliance
- How narrow airway is
- Size of ETT
- Suctioning
- Circuit
✔✔What is the most important pressure in ventilated patient? - ✔✔Plateau pressure
(Pplat)
✔✔Plateau pressure (Pplat) - ✔✔Measurement of pressure at alveolar level.
Keep <30 cm H2O
,✔✔Causes of increased plateau pressure (Pplat) - ✔✔- Anything that compresses lung
bases.
- Trendelenberg
- Ascites
- Abd compartment syndrome
- Obesity with supine position
- Pregnancy
- Increased Vt
- ARDS
- Tension Pneumo
- Pulmonary edema
- Pleural effusion
✔✔PIP 48, Pplat 18
What could be the cause? - ✔✔Upper airway issue as PIP is high, Pplat is ok.
✔✔PIP 48, Pplat 38 in trauma pt.
What is the cause & treatment? - ✔✔Tension pneumo.
Immediate needle decompression.
✔✔PIP 48, Pplat 38 non-trauma pt.
Causes? - ✔✔Fluid in lungs
Ascites
And compartment syndrome
✔✔If Pplat elevated, what do you do? - ✔✔1. What's the patho? Correct anything you
can.
2. By: Decrease by 1 ml. Then re-check Pplat. If remains high, decrease by 1 again &
re-eval. Only decrease to 4 ml/kg. If no change, see #3.
3. Change from volume to pressure delivery.
- start at 20 for adult
- 10-15 for ped.
✔✔Absorptive Atelectasis - ✔✔Nitrogen sits in alveoli after O2 is diffused resulting in
intrinsic PEEP 3-5. High concentration O2 causes nitrogen washout. Need to maintain
PEEP to prevent absorptive atelectasis.
,✔✔Respiratory Cycle Time
Calculation in regards to I:E ratio - ✔✔RR = 10
Cycle time = 60 sec
10/60 = 6 sec.
I:E — 1:2
Insp time 2 sec
Exp time 4 sec
Total 6 sec
Changing resp rate will change I:E ratio
✔✔Why would you clamp an ETT when moving pt from referral ventilator to transport
ventilator? - ✔✔Maintain recruitment.
✔✔Quickest way to increase oxygenation - ✔✔PEEP
✔✔PEEP Definition - ✔✔Pressure applied to airway at end expiration to maintain
alveolar recruitment.
✔✔Gas Laws in relation to PEEP (2) - ✔✔Henry's Law - make alveoli bigger for more
diffusion potential.
Fick's Law — make alveolar membrane thinner to allow better diffusion.
✔✔Complication of PEEP - ✔✔Decreased venous return.
✔✔Variable Rise Time - ✔✔- How long does it take to get to its peak pressure.
Ex. Going to Disney on vacation
- How long to get there = rise time
- How long stay at Disney park = Itime
- Only in pressure mode.
- Default = profile 4 = 0.237 sec (time breath delivered.
✔✔Causes of slower rise time (Profiles 5-9) - ✔✔- Small ETT
- Bronchospasm
- Pressure overshoot
✔✔Causes of faster rise time (Profilea 1-4) - ✔✔- Short Itime
- Hypoxic - air starved
, - Bipap (rise time 1)
✔✔Flow Termination - ✔✔- How the vent knows when to terminate a spontaneous
breath in SIMV.
- select % of peak Inspiratory flow at which PS breaths are terminated.
- only applies to SIMV & spontaneous breaths.
- Ex: vent set to terminate breath at 40%.
Flow set at 100 L/min
40% of total flow - terminates once is reaches 60 L/min
- can regulate TV by regulating flow termination.
- ex: flow term 40% of 100 L/min
Terminates incentive flow reaches 60 L/min.
Flow term 10%
Terminates once flow reaches 90 L/min vs 60 L/min at flow term 40%.
✔✔Assist Control - ✔✔- Volume or pressure controlled
- Delivers preset tidal volume & RR
- Delivers preset Vt with each triggered breath.
- Need to be very cautious with auto-triggering. Ex. If trigger (sensitivity) set too low,
can shake tubing & trigger vent. Can even have triggering by vibration of aircraft. Can
cause air trapping.
✔✔SIMV - ✔✔- Volume or pressure
- Pt receives set number of breaths at a preset tidal volume, allowing for spontaneous
breathing between mandatory breaths.
- Pt able to trigger own breath based on sensitivity.
- Can add pressure support (little "boost" at end of circuit that "helps along" pt
spontaneous breath).
- The first breath of every cycle is assisted. Every breath after in each cycle is whatever
pt wants. Saves from auto-triggering.
✔✔SIMV Indications - ✔✔- Often used with PS.
- Weaning
- Increased comfort
- Decreased chance of hyperventilation
✔✔SIMV
SOLUTIONS RATED A+
✔✔Exhaled tidal volume (Vte) - ✔✔Most accurate measurement of volume received by
pt.
Should be within +/- 50 of set Vt.
Only available in volume setting on ventilator.
✔✔Trigger - ✔✔AKA sensitivity
Set range from low to high with the lower number representing an easier amount of
force to initiate breath; the higher the number, the more effort to trigger breath.
✔✔Pressure trigger - ✔✔Pt has to draw in certain amount of pressure (usually -2 or -3)
to trigger a breath. Based on mode, it will either deliver the breath or allow pt the ability
to take a spontaneous breath.
✔✔Peak Pressure (PIP) - ✔✔Only used in volume controlled ventilation.
Measurement of pressure at upper airway, ETT, vent circuit, bronchial tree.
Always the highest pressure on vent.
✔✔Peak Inspiratory Pressure (PIP)
Normal value - ✔✔Keep <40 cm H2O
✔✔Peak Inspiratory Pressure (PIP)
Things that affect value - ✔✔- Overall volume going down airway
- How fast volume is going in
- Compliance
- How narrow airway is
- Size of ETT
- Suctioning
- Circuit
✔✔What is the most important pressure in ventilated patient? - ✔✔Plateau pressure
(Pplat)
✔✔Plateau pressure (Pplat) - ✔✔Measurement of pressure at alveolar level.
Keep <30 cm H2O
,✔✔Causes of increased plateau pressure (Pplat) - ✔✔- Anything that compresses lung
bases.
- Trendelenberg
- Ascites
- Abd compartment syndrome
- Obesity with supine position
- Pregnancy
- Increased Vt
- ARDS
- Tension Pneumo
- Pulmonary edema
- Pleural effusion
✔✔PIP 48, Pplat 18
What could be the cause? - ✔✔Upper airway issue as PIP is high, Pplat is ok.
✔✔PIP 48, Pplat 38 in trauma pt.
What is the cause & treatment? - ✔✔Tension pneumo.
Immediate needle decompression.
✔✔PIP 48, Pplat 38 non-trauma pt.
Causes? - ✔✔Fluid in lungs
Ascites
And compartment syndrome
✔✔If Pplat elevated, what do you do? - ✔✔1. What's the patho? Correct anything you
can.
2. By: Decrease by 1 ml. Then re-check Pplat. If remains high, decrease by 1 again &
re-eval. Only decrease to 4 ml/kg. If no change, see #3.
3. Change from volume to pressure delivery.
- start at 20 for adult
- 10-15 for ped.
✔✔Absorptive Atelectasis - ✔✔Nitrogen sits in alveoli after O2 is diffused resulting in
intrinsic PEEP 3-5. High concentration O2 causes nitrogen washout. Need to maintain
PEEP to prevent absorptive atelectasis.
,✔✔Respiratory Cycle Time
Calculation in regards to I:E ratio - ✔✔RR = 10
Cycle time = 60 sec
10/60 = 6 sec.
I:E — 1:2
Insp time 2 sec
Exp time 4 sec
Total 6 sec
Changing resp rate will change I:E ratio
✔✔Why would you clamp an ETT when moving pt from referral ventilator to transport
ventilator? - ✔✔Maintain recruitment.
✔✔Quickest way to increase oxygenation - ✔✔PEEP
✔✔PEEP Definition - ✔✔Pressure applied to airway at end expiration to maintain
alveolar recruitment.
✔✔Gas Laws in relation to PEEP (2) - ✔✔Henry's Law - make alveoli bigger for more
diffusion potential.
Fick's Law — make alveolar membrane thinner to allow better diffusion.
✔✔Complication of PEEP - ✔✔Decreased venous return.
✔✔Variable Rise Time - ✔✔- How long does it take to get to its peak pressure.
Ex. Going to Disney on vacation
- How long to get there = rise time
- How long stay at Disney park = Itime
- Only in pressure mode.
- Default = profile 4 = 0.237 sec (time breath delivered.
✔✔Causes of slower rise time (Profiles 5-9) - ✔✔- Small ETT
- Bronchospasm
- Pressure overshoot
✔✔Causes of faster rise time (Profilea 1-4) - ✔✔- Short Itime
- Hypoxic - air starved
, - Bipap (rise time 1)
✔✔Flow Termination - ✔✔- How the vent knows when to terminate a spontaneous
breath in SIMV.
- select % of peak Inspiratory flow at which PS breaths are terminated.
- only applies to SIMV & spontaneous breaths.
- Ex: vent set to terminate breath at 40%.
Flow set at 100 L/min
40% of total flow - terminates once is reaches 60 L/min
- can regulate TV by regulating flow termination.
- ex: flow term 40% of 100 L/min
Terminates incentive flow reaches 60 L/min.
Flow term 10%
Terminates once flow reaches 90 L/min vs 60 L/min at flow term 40%.
✔✔Assist Control - ✔✔- Volume or pressure controlled
- Delivers preset tidal volume & RR
- Delivers preset Vt with each triggered breath.
- Need to be very cautious with auto-triggering. Ex. If trigger (sensitivity) set too low,
can shake tubing & trigger vent. Can even have triggering by vibration of aircraft. Can
cause air trapping.
✔✔SIMV - ✔✔- Volume or pressure
- Pt receives set number of breaths at a preset tidal volume, allowing for spontaneous
breathing between mandatory breaths.
- Pt able to trigger own breath based on sensitivity.
- Can add pressure support (little "boost" at end of circuit that "helps along" pt
spontaneous breath).
- The first breath of every cycle is assisted. Every breath after in each cycle is whatever
pt wants. Saves from auto-triggering.
✔✔SIMV Indications - ✔✔- Often used with PS.
- Weaning
- Increased comfort
- Decreased chance of hyperventilation
✔✔SIMV
