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EMS > Vents > Flashcards

Vents Flashcards

1
Q

Minute volume

A

RR X Vt 4-8LPM average adult (most around 5LPM)
Infants (0-1) 0.2-0.3 L/kg/min
Cardiac output also 4-8LPM

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2
Q

Tidal Volum

A

Vt - volume per normal quiet resp. Calculated on IBW and needs to overcome anatomical deadspace

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3
Q

Deciding resp rate

A

Injury vs obstructive (start everyone at 6mL/kg)
Obstructive 10-12 breaths/min (4-6mL/kg)
Injury (6-8mL/kg) use 100mL/kg/min for minute ventilation for example 70kg = 7L/min start at 6mL/kg so Vt of 420 mL
Then minute vent / Vt so 7000/420 = 16.6
16 resps/min of 6mL/kg will get you 100mL/kg/min
This seemingly fast rate is needed to overcome anatomical deadspace

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4
Q

Anatomical dead space

A

1mL/lb. IBW 70kg = 150lb =150mL per breath or 2.4L/minute
Remember vT is 6mL/kg so 420mL.
420mL-150mL = 270 is what is delivered to alveoli
7L-2.4L is 4.6L

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5
Q

Mechanical dead space

A

2mL X PIP for adults - usually not an issue
1mL X PIP for peds - matters
Less with volume breath?
Hamilton only factors in anything attached AFTER flow sensor

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6
Q

Equipment pieces contribution to mechanical dead space

A

HME filter (normal) 30mL/min
ETCO2 50mL/min
Viral filter - up to 90mL/min

divide by 60 to get loss per second

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7
Q

Exhaled vT

A

If there are no leaks then this is a good number for figuring out how much pt received - accounts for mechanical dead space

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8
Q

I:E

A

Starting 1:2 for adults 1:3 for peds

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9
Q

PIP

A

Peak pressure at ETT, vent circuit, bronchial tree
Based on how fast breath is delivered
Should be under 35mmHg but it may not be possible in obstructive pts
Will never be lower than Pplat

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10
Q

Causes of increased PIP

A

Pt coughs
Secretions/suctioning
Sedation Status
Small ETT
Kinked tube or vent circuit
or is it pathology like asthma (B2s)

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11
Q

Pplat (plateau pressure)

A

Only applicable in volume breaths (considering switching to volume after all troubleshooting done)
Should be <30cm H20 (<30 leads to barotrauma)
Reflects the alveoli pressure
If >30 we should drop volume (drop down to 5mL/kg then 4mL/kg)
Can’t really go below 4mL/kg due to mechanical and anatomical deadspace 280mL-150mL (4mL/kg - all dead space)
130mL

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12
Q

Causes of increased Pplat

A

Increased volume
Decreased compliance
Pulmonary edema
Pleural effusion
Peritoneal Gas insufflation
Trendelenburg
Tension pneumo
Ascites
Abdo packing

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13
Q

Driving pressure

A

= critical opening pressure of the airway
(only in volume) Product of taking a plateau pressure and subtract peep that is driving pressure
Used in ARDS pts (better than plat for these pts)
Target 15cm H20 or less (decreased mortality in ARDS)

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14
Q

PEEP

A

Increases alveoli surface area and thins out membrane to increase gas exchange
Improves V/Q mismatch
Everyone gets 5
Remember to clamp ETT at peak of inspiration
Remember decreased preload

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15
Q

Volume vs pressure

A

T1 is always pressure
Volume breath - mandatory volume given
Pressure breath - considered lung protective as it is compliance based. Start adults 20 peds 10cmH20 and monitor exhaled volume (Vte) and aim for 6mL/kg.

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16
Q

A/C vs SIMV

A

The difference being if a pt triggers a breath A/C gives a full breath, where as SIMV can simply open the circuit or assist with pressure but Vt is dictated by pt effort.
A/C is easier to over ventilate if things like road noise/turbulence trigger a breath so may be better for controlled environments
Pressure support (like BiPap) reduces dead space and pt effort.
SIMV is easier to undervent pt (in controlled setting it ensures resp muscles aren’t simply too weak)

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17
Q

Pressure trigger

A

-2 to -3 cmH20 standard starting point adults and -1 peds
Pt needs to be able to create negative pressure (dropping diaphragm)
This number is based off PEEP so set to -2 at 5 of PEEP vent will trigger AT 3 cmH20

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18
Q

Flow trigger

A

Flow sensor senses absence of flow rather than negative pressure
Example: Flow trigger set at 5L/min means 5000/60 - 83mL/second.
Flow sensor is reading volume in volume out and a change in 83mL/second because pt is moving diaphragm.
If increase number means change in flow needs to be greater before breath triggers
If set too low the movements may sense absence of flow and trigger breath - if A/C they get full breath SIMV they wouldn’t get a breath

19
Q

PRVC

A

Pressure regulated volume control (REVEL vent specific to this method). Hamilton has a spin-off called volume adaptive (essentially same thing)
Most popular in hospital as its constantly adjusting to what pt is doing

20
Q

Volume adaptive on T1

A

Called PRVC by revel
Set a desired volume - machine gives a test breath and compares Vt to Vte and adjusts pressure to get desired volume (adjusts up by 2-3cm H20)
Compliance is driving the pressures given, compliance is dynamic, which is good
Downside it takes 6 or 8 breaths to get to desired volume so if something goes wrong during transport it can cause issues

21
Q

PRVC vs pressure control

A

PRVC constantly adjusts pressure to aim for desired volume where as pressure control you are controlling pressure. Machine can’t critically think so if anything aside from pt’s own compliance is changing breath delivery (like during transport) pressure controlled is likely better

22
Q

Ppeak =

A

airway resistance and alveolar compliance.
Less than 35mmHg ideally (less than 30mmHg on T1)
May go up to 40mmHg in pts with high airway resistance

23
Q

Airway resistance calculation

A

PIP-Pplat/flow (in litres per second)
>10 is a problem and says you have a resistance issue

24
Q

Common flow rates for calculating airway resistance

A

40L/min = 0.67lps (litres per second)
50L/min = 0.83lps
60L/min = 1lps

25
Q

Dynamic compliance calculation (airway resistance and alveolar compliance)

A

Vt/PIP-PEEP
Standard is 40-100mL/cmH20

26
Q

Static compliance (alveolar compliance)

A

True static compliance is inspiratory hold and finding Pplat
Vt/Pplat-PEEP (or Pplat-PEEP = driving pressure)

27
Q

Peak inspiratory pressure

A

Hamilton calls it Ppeak
Don’t usually want to exceed 35 (rt books say 40)
Lung protective 30 or less

28
Q

High pressure alarm limit (T1)

A

Terminates the breath 10cm below high alarm limit.
Flow is limited but doesn’t entirely terminate breath

29
Q

Inspiratory resistance

A

Safe is 8 or less
8-25 is yellow
Above 25 is red

30
Q

Static compliance (Cstat)

A

Overall compliance (includes lungs and chest wall)
100-50 good
Under 40 is poor compliance

31
Q

RCexp

A

Expiratory time constant- indication of the length of time it takes to exhale 95% of volume exhaled
Multiply RCexp x 3 to get desired E time
Normal is .6 to .9
Below .6 is stiff lung
Above 1 is obstructive

32
Q

Pmean

A

Mean airway pressure
15 to 25 normal
Above 30 is red
Higher pressures have more impact on hemodynamic status.
Flightbridge says treat oxygenation with higher pressure then support with vasopressors

33
Q

Pmean

A

Mean airway pressure
15 to 25 normal
Above 30 is red
Higher pressures have more impact on hemodynamic status.
Flightbridge says treat oxygenation with higher pressure then support with vasopressors

34
Q

Driving pressure

A

Delta P.
In lung injured aim for less than 15.
Calculated by Pplat-PEEP

35
Q

Auto PEEP

A

Should be 0
Yellow 2-10
Red over 10

It’s amount of volume not being exhaled.
Poor sedation, overtriggering vent, need to increase I:E
Also pop tube squeeze chest

36
Q

VTI

A

Inspiratory tidal volume
A higher VTI than VTE may indicate leak (measured at flow sensor)

37
Q

VLeak

A

Expressed in percentage
Green under 10
Yellow 10 to 20
Red over 20
Use hamilton mask specifically

38
Q

Notch prior to breath

A

Pt triggered breath
Failed if no breath after

39
Q

Flow waveform

A

Set as second screen?
Not returning to baseline is autopeep (I:E ratio? Sedation?)

40
Q

Common dosing for RSI

A

Ketamine 1.5mg/kg (protocol doesn’t say IBW but LITFL does
Etomidate 0.3-0.4mg/kg TBW
Fentanyl 2-10mcg/kg TBW
Midaz 0.1-0.3mg/kg TBW
Propofol 1-2.5mg/kg IBW plus 0.4 x TBW or 1.5mg/kg as a general guide
Succ 1-2mg/kg max 150 TBW
Roc 0.6-1.2mg/kg IBW
Vecuronium 0.15-0.25mg/kg IBW

41
Q

Common dosing for RSI

A

Ketamine 1.5mg/kg (protocol doesn’t say IBW but LITFL does
Etomidate 0.3-0.4mg/kg TBW
Fentanyl 2-10mcg/kg TBW
Midaz 0.1-0.3mg/kg TBW
Propofol 1-2.5mg/kg IBW plus 0.4 x TBW or 1.5mg/kg as a general guide
Succ 1-2mg/kg max 150 TBW
Roc 0.6-1.2mg/kg IBW
Vecuronium 0.15-0.25mg/kg IBW

42
Q

HFNC

A

Try after O2 before CPAP
Idea is to increase fio2, moisture and temp of oxygen
Gives 100% fio2
Reduces anatomical and mechanical dead space
Reduces CO2 rebreathing
Improved alveolar oxygenation and ventilation
Reduces WOB
Decreases airway inflammation and airway resistance
Improves lung compliance and mucociliary resistance

43
Q

Ventilation for massive PE

A

Low PEEP
Avoid high plateau pressures
High fio2
?keep pt breathing spontaneously if possible

44
Q

Nitro neb

A

12.5mL of 200mcg/mL at 8lpm should be about 2-2.5mcg/kg/min. Cuts pulmonary pressures roughly in half, mean drop of 18mmHg.
(PE takes pulmonary pressures from normal of 20 to 40+)

EMS (5 decks)

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