vents TA 1

Question 1

What other names can APRV have ?

Answer 1

Bilevel
BiPAP
BiVENT
DuoPAP

Question 2

What is the criteria for APRV ?

Answer 2

• Fixed times at both high and low level pressures
• inverse ratio ( I : E ) ventilation
• must induce air-trapping
• pt can theoretically breath spont at both pressure levels

Question 3

advantages of Volume control

Answer 3

• precise MV control
  guaranteed volume and rate
  -can be triggered with pt effort
  -can provide full support

Question 4

Disadvantages of Volume control

Answer 4

• pressures can vary ( high pressures) is a problem if high alarms are not set properly
• Uncomfortable for awake pt
• can cause Alkalosis if trigger is too sensitive ( increase in MV)
• muscles atrophy if prolong use

Question 5

Advantages of PC

Answer 5

• precise control on pressure
• less danger on over distending the lung due to excess pressure
  -pt can access flow by triggering
• Improved WOB and is better tolerated in awake pts

Question 6

Disadvantages of PCV

Answer 6

• Risk of resp alkalosis with excessive pt triggering
• Increase Volumes with increase in pt effort may cause injury due to excessive stretch
• no CO2 control
• muscle atrophy of prolonged use

Question 7

when should we use SIMV ?

Answer 7

• to facilitate weaning ( 1st by deacreasing RR and the decrease support)
• for pts who have a variable drive to breath ( gives a minimum ventilation)
• reduces breath stacking

Question 8

disadvantages of SIMV

Answer 8

inferior to PSV
is no better than control modes for asychrony and may be worse in trauma patients

Question 9

Advantages for SIMV

Answer 9

• Mode use for weaning
• provides a minimum minute ventilation

Question 10

Advantages of pressure support

Answer 10

better synchrony btw pt and ventilator (more comfortable)
increase in work of breathing ( PS support)
training of muscles
decrease in oxygen cost of breathing

Question 11

Disadvantages of PS

Answer 11

Need a drive to breath
can under or over ventilate pt
doesnt give you a fixed MV

Question 12

PRVC advantages

Answer 12

• ventilating pressures will be lower
• more comfortable with pt
• Vt is not exact but is relatively consistent
• may decrease risk of overdistension
• breath is more adaptive if the patient is interacting with it

Question 13

Disadvantages of PRVC

Answer 13

As it works on a feedback mechanism if there are rapid changes, ventilator may struggle to determine next breath ( pt coughing, dramatic swings in effort to breath)
- If pt is triggering for more flow (Vt) the vent may reduce pressure getting less support, this may fatigue pt overtime.

Question 14

What is MMV ?

Answer 14

MMV is an auto adjusting mode. (lets patient go back and forth from control to spontaneous mode)
like the name suggest it gives minimum minute ventilation even when the pt is not breathing.
mode is found only on evita vent

Question 15

MMV disadvantages

Answer 15

• only on Evita
• when it cycles to control mode (VC) it may be uncomfortable for the patient
• pt able to maintain MV above set MV even while tiring out ( it never cycles to a control breath unless your MV is less than what you had set)

Question 16

Advantages of MMV

Answer 16

• provides minimum minute ventilation
• Good on patients that have an erratic drive to breath
• prevents hypoventilation

Question 17

What is PC-PSV ?/

Answer 17

is an auto- adjusting mode that lets patients with an erratic drive to breath switch from a pressure support mode ( spontaneous) to a PC mode when they breath below the set RR.

Question 18

Advantages of PC-PSV ?

Answer 18

– prevents apnea and hypoventilation if the patient loses their drive to breath ( not all true because we dont what Vt is going to be once the patient is not making efforts)

Question 19

what is automode trigger timeout ?

Answer 19

• the longest possible time for the pt to be apneic which is 12 seconds

Question 20

What is ASV ?

Answer 20

ASV is a mode only found in the Hamilton ventilator.
- It determines the pt MV by the clinician in putting the pt’s sex and height. Once it gets their Ideal MV it determines their ideal RR, Ti and driving pressures to keep the pt in the golden zone or their ideal MV

Question 21

Advantages of ASV

Answer 21

• Easy to set up
  -requires minimal adjustment once started
  -safely guarantees minute ventilation

Question 22

Disadvantages of ASV

Answer 22

• pt can tired out if they want a greater MV
• can’t adjust to ABGs
• doesn’t know what to do when people fall out of the golden zone
  -no ability to automatically wean pt

Question 23

Advantages of APRV

Answer 23

• Improves time constant
• may open atelactic alveoli by sustained pressures (Phigh 5-7 secs)
• Allows for better gas mixing in the alveoli (increase aveolar surface are
• high mean airway pressure, while controlling PIP

Question 24

In what mode is Pplat and PIP equal ?

Answer 24

Pplat and PIP are the same in APRV and that is because you are holding pressure constant almost like an inspiratory hold. (PIP is usually started btw 18-26 cmH2O) with a Pplat < 30

Question 25

How is Autopeep created in APRV ?

Answer 25

- Because Thigh is so long (5-7 secs) and a Tlow very shot (0.5- 1.0 secs) we dont have enough time to exhale all that volume out. ( we cant never reach FRC and that creates Autopeep (air-trapping)

Question 26

Disadvantages of APRV

Answer 26

- can be uncomfortable for the patient (sedation required) - High mean airway pressure can impact cardiac function (venous return) - difficult to set up - May not work on patients requiring high MV - bad for pts who have obstructive disease

Question 27

How is PAV determining elastance and Resistance ?

Answer 27

- by doing a short insp pause randomly every 6-10 breaths. Volume and flow its determined by measuring circuit pressures. ( Once the ventilator knows the pts elastance and resistance it can calculate the pts effort and this is calculated 200 times per second during inspiration)

Question 28

what is PAV ?

Answer 28

Is a solely spontaneous mode that measure pt's inspiratory effort in order to supply the correct support pressure or amplify pressure. The more effort you are making the more support your are getting.

Question 29

What is percent support ?

Answer 29

Is an amplification of the pt's effort, this setting is used on PAV modes. It sets how do we want the vent to work for out patient example 50% percent support means 50 of the work falls on the patient and the other 50 is provided on the vent

Question 30

Advantages of PAV

Answer 30

- No free rides, pt always have to generate an effort to get the support from the ventilator - gives numerical estimate of the effort the pt is making -support changes in proportion to pt effort - improves synchrony - constantly measure compliance (elastance) and resistance ( volume)

Question 31

Disadvantages of PAV

Answer 31

- purely spontaneous (back up apnea alarm, does't give you exact MV) - must have a sealed circuit, can't use for NIV or there is a leak - relies on accurately measures C and R if these are off then we can missed calculated and give the wrong support - We can give way more pressure than what the pt actually needs when percent support is at higher levels

Question 32

Explain what NAVA is

Answer 32

Neurology adjusted ventilatory assist is an advance support mode on servo that measures patients efforts based on the electrical signal from the phrenic nerve as it passes across the diaphragm using either an NG or OG. Support is multiple !!! NAVA X EDI the level of support is measured every 3 milliseconds--- making support variable throughout the entire breath

Question 33

When is the pt considered Weaned on the NAVA mode ?

Answer 33

- pt should have an EDI less than 10 on a NAVA level less than 1 cmH20/ uV *** Remember normal values for Edi on a healthy person are btw 3-8 uV and we start NAVA support at 1.0-1,2

Question 34

When to use NAVA ?

Answer 34

- Difficult to wean pts even post extubated pts -COPD or Pts with AutoPEEP - NIV -PEDS with uncuff tubes - Better sleep quality ( increase REM)

Question 35

Disadvantages of NAVA

Answer 35

Must have an intact phrenic nerve and signal to the diaphragm Spontaneous breathing only Avoid in brainstem or phrenic nerve injury Questionable for use with Sepsis or where drive to breathe is abnormal Staff must get used to a different concept of normal Doesn’t assess lung dynamics (Compliance and Resistance)