Ventilator Review
Trigger: What begins inspiration, either time, flow or pressure. The time applies to non patient triggered
breaths. Control trigger by setting sensitivity
Set sensitivity 1-3. If the sensitivity is set >3 may lead to difficulty triggering breath on and induce WOB,
if set to low may cause auto-triggering
Set in all modes (including CPAP, PSV still needs a trigger!)
Cycle: This is what cycles the breath off. Either flow, pressure or volume. Pressure and volume limits are
the most common
Volume: Set appropriate per patients size. If patient has restrictive lungs or is air trapping severely, use
5-7 ml/kg range
Pressure Limit: Set 15-25, increase to increase VT, decrease to lower VT
Flow: Set only in Volume control. When set use either constant or decelerating patterns. Increased
flow= decreased I-time. Give patients with COPD increased flows to meet demands and give long E-time.
Increase when you increase VT, or change flow pattern
I-time: Set in PRVC, PCV. Increase or decrease to achieve appropriate I:E, increased rates=decreased Itime. Inverse used for restrictive diseases to increase oxygenation
MODES:
AC: start with this mode if patient is apneic or if patient’s spontaneous breaths are inadequate or
erratic. Patient can trigger breaths but machine will complete the breath at preset limits
SIMV: May start with this mode on any patient who is apneic if you suspect he/she will regain
spontaneous breathing. Otherwise, use only if spontaneous breaths are adequate. Must set a PSV in this
mode
CPAP/Spontaneous: May start for Type I failure, patient must have ability to breathe spontaneously
without much need for ventilatory support. Must have a PSV or ATC or VS
PRVC: duel mode, set in either AC or SIMV mode. Set pressure limit, target VT…Does not work well with
erratic breathing patterns
Non-compensated Respiratory Acidosis:
You need to increase Ve. On AC mode this is done by:
Increasing VT (8-12 range), watch PIP’s
Increasing PIP, watch total PIP
Increasing rate, unless patient is breathing over BUR
increase Ve target if on MMV or ASV modes
Remove any unnecessary mechanical deadspace
On SIMV mode: you can increase rate even if patient is over BUR, or increase VT/PIP or increase PSV to
increase Spontaneous VTe
Uncompensated Respiratory Alkalosis
On ACV mode:
Decrease rate first if patient is not breathing over BUR.
Decrease VT or PIP
On SIMV decrease Rate, VT/PIP or PSV OR change to CPAP mode
Vent Check:
Check ventilator orders, check for new orders and assure old orders. Weaning orders? Pertinent
procedures that would require transport or procedures that would require your presence like a bronch?
 Assess patients chart first know patients
 CXR, CT scan and all other pertinent
Hx and why they are on the ventilator
diagnostic tests
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ABG, CBC, other pertinent labs
 Record monitored data including: PIP,
Sedation
VTE/VTI, Ve, Rate, Static Compliance,
Hemodynamics, BP, arrthymias and
Dynamic compliance, MAP, total PEEP…
cardiac status
 Check suction pressure, suction patients
 Note if patient is in isolation
lungs as needed and also mouth with
 Assess patient’s vital signs
yonker
 Check BS, HR, Spo2, cardiac rhythm, BP
 Document all pertinent information
and hemodynamics
 If you do not document it wasn’t done!
 Assess capnography if applicable
 Your first vent check should be the
 Note presence of Foley and its contents,
most time consuming.
chest tubes, NG tubes, PICC lines, IV’s,
 Any changes that are made, make sure
A-lines…
the patients RN is aware
 Note medications hanging in room
 As a student you will not be making any
 Note patients ETT tape or holder, does
changes without approval from your
it need to be changed
preceptor
 Note ETT size and location at lip.
 Typically a brief summary is written
 Note patient and their sensorium
regarding the patient. Put any changes
 Perform MLT/MOV or check cuff
you made or ABG’s you drew here and
pressure directly
maybe the plan for the day
 Ensure tubing is free from
 Inline HHN or MDI’s should be given
condensation, if patient is on a heater,
AFTER you have done your check and
drain circuit into water trap, ensure
suctioned patient (if it was needed)
heater water is filled. If HME, ensure it
 The patient should have a resusitation
is not occluded, if it is, change it
bag at bedside, plugged into oxygen. If
 Note inline suction ballard, if heavily
the patient is on PEEP, ensure there is a
soiled, change it
peep valve.
 Check patients settings, mode, VT/Pip,
 The ventilator should be plugged into
rate, rise time, sensitivity…also alarm
the red outlet incase of power outage
settings and apnea settings
 Note signs in room for Dialysis Shunts
 Assess ventilator graphics, note
 A spare trach should be in the room for
presence of over distension, air leaks,
trach patients
auto-peep, secretions…
Transporting patients:
o The hospital will either make you attach the patient to a transport ventilator or you will
bag the patient to their destination
o You may have to bring along the ventilator and attach it once you reach the area you are
transporting to, in this case, simply select same patient so that all the settings remain
o Have a full E-tank available. Assist in the pushing of gurney and also the attachment of
monitors
Troubleshooting
• If the ventilator is alarming and the immediate fix is not apparent, you must take the patient off
and bag them until the problem can be solved
•
For high pressure alarms: assess patient for asynchrony, fighting ventilator, mucus, change in
compliance, increase RAW, bronchospasm, biting tube…. Inform your preceptor if you can not
resolve the issue yourself. For example patient is biting tube, inserting an oral airway, don’t do it
alone
Consider the following:
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Secretions in airway
Cough
Increased airway resistance
Bronchospasm
Decreased compliance
Atelectasis
Fluid overload
Pneumothorax
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Tube block
Kinking of tube
Biting the tube
Water in the tube
Cuff herniation
Rt. bronchial intubation
Fighting the ventilator
If the low pressure, or low Vte alarm is sounding.
 Check for obvious leaks, if a leak if found plug it
 Check cuff pressure, if blown, let your preceptor know, the ETT may have to be changed
 If patient self extubated, and it is plainly obvious (tube is seen hanging from patients
mouth), finish the extubation, bag as needed and call for help
Consider the following:
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Cuff leak.
Leak in the circuit
Loose connections
ET tube displacement
Disconnection
Inadequate flow
Low supply gas pressures
FiO2 to 100%
Check all connections for leaks. Start
from ventilator inspiratory outlet—
humidifier—inspiratory limb—
nebulizer—Y junction—dead space—et
tube cuff—expiratory limb—expiratory
valve.
 If inspiratory effort excessiveinadequate flow—increase inspiratory
flow, decrease Ti, increase TV
 Check gas pressures
 If all normal and problem persists,
change ventilator
Weaning:
Some of the objective parameters used in determining whether a patient is able to come off the
ventilator include: (a) PaO2/FiO2 ratio >150-200; (b) level of positive end expiratory pressure
(PEEP) between 5-8 cm H2O; (c) FiO2 level <50%; (d) pH > 7.25; and (e) ability to initiate spontaneous
breaths. Some of the subjective parameters used in determining the ability to liberate
from mechanical ventilation include: (a) hemodynamic stability; (b) absence of active myocardial
ischemia; (c) absence of clinically significant, vasopressor-requiring hypotension; (d) appropriate
neurological examination; (e) improving or normal appearing chest radiogram; and (f) adequate
muscular strength
• allowing the capability to initiate/sustain the respiratory effort.
• If the patient is to be weaned…
– Perform weaning parameters. This may be done through the ventilator on
most modern vents. If you are to do a VC or MIP, the patient is typically on
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CPAP mode without PEEP and minimal PSV if any. Assess VC, MIP, MEP
several times for reproducibility
While weaning note vital signs, RSBI, Vte, RR, SpO2…
If patient fatigues to the point that their vitals decline, you should place
them back on previous mode/settings
You may get a ABG after a short time frame while weaning to assess
effectiveness
– Weaning can be done numerous ways…SBT, CPAP trials, to Bipap…
Ventilator Formula Review:
A-aDo2: A-a gradient,
norm 5-10 mmHg on .21, 30-60 on 100%, >350mech support, <350 weaning.
Represents potential to Oxygenate vs. the amount of O2 in the artery. Every 50mmHg is approx. 2
percent shunt above norm of 2-5%
Increased A-a= SHUNT
a/A ratio: PaO2/PAO2 norm is 90%, >35%weaning, reflects efficiency of oxygenation as a percentage,
<74% shunt, V/Q mismatch or diffusion defect
Anion Gap= the difference in the measured cations and the measured anions in serum, plasma, or
urine. Used to assess Metabolic Acidosis or alkalosis, normal around 8-16 mEq/L. Use MUDPILES to
determine cause of metabolic acidosis (high gap)
= ( [Na+] ) − ( [Cl−]+[HCO3−] ) without potassium
= ( [Na+]+[K+] ) − ( [Cl−]+[HCO3−] ) with potassium
CaO2: norm 20 vol%
(Hbx1.34)SaO2 + (PaO2x.003) total amount of O2 carried in 100ml of blood, combined content of O2
carried on Hb and dissolved in plasma,
(can be reduced by <Hb, anemia or <CO)
CvO2: (Hb x 1.34)SvO2 + (PvO2 x .003)
norm is 15 vol%, represents the value of O2 in blood returning to the right side of the heart after tissues
have oxygenated.
C(a-v)O2 = arterial to mixed venous oxygen content difference
Determines how well the tissues take up O2
VO2: O2 consumption,
norm is 250mL/O2/L/min,
[C(a-v)O2 x QT] x 10, the amount of O2 consumed by the body per liter of blood per minute.
Time Constant: The given % of a passively exhaled breath of air will require a constant amount of time
to exhale
Depends on the resistance and compliance of the lung
TC= R x C (in liters)
TC: Time constant, (Raw x CS)e,
where e represents volume exhaled as a percent,
1 is 63%,
2 is 86%,
3 is 95%
5 is 100% exhaled.
TC <3 leads to air trapping.
DO2: O2 Delivery, (CaO2 x CO) x 10, norm is 1000mL/O2/min
The ability of oxygen to tissues based on cardiac output and Hb
I-time = Inspiratory Time,
E-time = Expiratory time,
TCT= total cycle time (I +E)
I-time when compared to E-time will always be a 1: something ratio.
Respiratory rate = 60 /TCT
EXAMPLE: Calculate I:E ratio, rate and TCT if I-time is 1.2 seconds and E-time is 3 seconds.
TCT = 1.2+ 3 = 4.2
Rate = 60/4.2 =14
I:E = TE/TI = 3/1.2 = 2.5, (I:E is 1:2.5)
Example: The ventilator is set at 12 breaths per minute with an IE ratio of 1:3. How many seconds for
inspiratory time?
Seconds per breath = 60 divided by 12 = 5 seconds
TI=5/(1+3) =5/4=1.25 seconds
Example: The ventilator is set at 12 breaths per minute with an IE ratio of 1:3. How many seconds for
inspiratory time?
Seconds per breath = 60 divided by 12 = 5 seconds
TI=5/(1+3) =5/4=1.25 seconds
Since I/E = 1:3, the expiratory time = 1.25 • 3 = 3.75 seconds
Note: 1.25 + 3.75 = 5 seconds (the number of seconds per breath in this case.) ( a breath equals
inspiration + expiration)
Flow = VE x (I+E)
Example: Calculate flow given:
VT 600
Rate 12
IT 1.5
ET 3
600 x 12 = 7.2 L x (1.5 +3) = 31.5 (32 L)
Suction size
No more than ½ the internal diameter of ETT or else improper entrainment.
French divided by 3.14 = size in mm. normal adult sizes 12 - 14 fr
O.D. of catheter should not exceed 1/2 I.D.of airway
(1) to determine size of suction catheter for given ET tube: ETT size / 2 then x 3.14
(2) always round down – i.e. 7/2 x 3.14 = 10.99, use a 10 French
OR
Size of tube -2 then x 2.
Example: 8 ETT – 2 = 6 x 2 = 12F
Mean Airway pressure (Paw): ½ (PIP-peep) (TI/TCT) + PEEP
Average amount of pressure throughout the TCT
PIP 25
PEEP 5
IT 1
TCT 4
VE = actual VE x actual PaCO2
desired PaCO2
New rate = Current rate x actual PaCO2
desired PaCO2
New Vt = Current Vt x actual PaCO2
desired PaCO2
Desired FIO2 = (desired PaO2)(known FIO2) / known PaO2
Shunt Equation:
QS/QT: Pulmonary Shunt equation
(CcO2-CaO2)/(CcO2-CvO2)
Norm 2-3%,
>20% vent indication,
<20% weaning,
>30% is life threatening.
Measures % of QT not exposed to ventilation, shunts caused by atelectasis, edema, pneumonia,
pneumothorax, obstructions
CcO2: Content of pulm capillary blood oxygen at 100% FIO2, (Hbx1.34)1 + (PAO2x.003) used in shunt
equation
VTspont: (total Ve – Set Ve) / Spontaneous rate
Measured when machine in SIMV mode, represents what the patient is actually breathing on his/her
own.
Example:
Total Ve 8L
RR set 10
VT set 500
RR total 20
(8,000 – 5,000) / 10= 300 ml
VEspont: VEtot- Mech Ve norm 5-6 L/min,
Calculated when patient is in SIMV mode
Example:
Ve total= 12
VT Set = 500
RR Set= 10
(12L -5L ) = 7 L
VC: Vital capacity, 65-75 mL/kg, <10mL/kg indicates support, 10-15 mL/kgweaning
Maximum inhalation followed by a maximum exhalation
Measured by a Wright Respirometer
RSBI: Rapid shallow breathing index,
RR/VT (in liters), <100 weaning
must be calculated during spont breathing, press support reduces predictive value
MIP/NIF: Max Inspiratory Press, norm -80 - -100, > -20 support indicated, <-20 weaning (remember that
negative numbers are larger as they become less, -25 < -20)
PAP: pulmonary artery pressure, norm 25/10 (20-35/5-15), >35/15 is inconsistent with weaning, pulm
hypertension, left vent fail, fluid overload
PCWP: pulmonary artery wedge pressure, norm 5-10 mmHg, >18 is inconsistent with weaning, left vent
failure, fluid overload
CVP: central venous pressure, norm 2-6 mmHg, 2-6 weaning
Plateau pressure: The amount of pressure held in the lung during a brief inspiratory pause. This is used
to calculate static compliance. The higher this number the worse the patients compliance as it
represents distending pressure. Typically less than PIP, but more than MAP.
Ventilator Lab
(4 groups)
Group 1: PB 840
A 65 year old man, 5’7 arrives to the ER with respiratory failure. His RR is 38, spontaneous VT 300, HR
142, with a BP of 152/98. The patient has a long history of COPD, BS currently with bilateral wheezing,
decreased bibailser.
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Set the patient on initial settings including alarm limits and apnea
______________________________________________________________________________
______________________________________________________________________________
Perform a static compliance_____________________________________
Calculate Dynamic compliance___________________________________
30 minutes later an ABG is drawn with results:
7.28, paCO2 89, PaO2 50, HCO3 35.
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The patient is apneic. Calculate the new rate and VT if desired PaCO2 is 65__________________
Calculate a new FIO2 if the desired PaO2 is 60_____________________________
A 36 year old with diabetes is admitted for wound healing for a possible gangrene of her left foot. The
patient develops subsequent sepsis and respiratory failure. The patient was intubated and placed on
the vent initially in PCV mode. Plateau pressures while on PCV were 25. Patient’s PaO2 is 50, on 80%
FIO2.
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Initiate SIMV VC, achieve a pressure less than 25 (adjust volume)
______________________________________________________________________________
Set PSV above patients RAW
1 hour after initiation an ABG is drawn: 7.25, 68, 50, 28
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How would you increase this patients PaO2?_________________________________________
How would you decrease the patients PaCO2?________________________________________
If this patient was improving how would you wean this patient___________________________
A 29 year old patient was just in a MVA. The patient is 5’9, man, with no prior medical problems. The
patient has a suspect intracranial bleed and flail chest. The patients left lung is decreased with
tracheal deviation to the right.
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What are the immediate treatments for this patient?___________________________________
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Set this patient up (post treatment for above) on the ventilator using VC+. Set PIP, VT, I-time,
Rate, FIO2 and alarms____________________________________________________________
Would you suggest capnography for this patient? If so why_______________________________
Group 2: Espirit Ventilator
A 82 year old woman, 5’3 is admitted from a convalescent home with suspected pneumonia and
dehydration. The patient is hypotensive, has bilateral rhonchi. ABG on 40% venturi mask showed:
7.28, 56, 55, 16, -8
The patient’s RR 29, Vte spontaneously is 150-200. Patient has a fever, no cough reflex. The patient is
intubated.
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Set the patient on initial settings including alarm limits and apnea
______________________________________________________________________________
______________________________________________________________________________
Perform a static compliance_____________________________________
Calculate Dynamic compliance___________________________________
Adjust ventilator to achieve a I:E ratio of 1:3
The patients CXR shows bilateral pneumonia. You are unable to suction much out, what would
you recommend?_______________________________________________________
What other treatment or tests would you recommend for this patient with suspected
pneumonia? ______________________________________________________________
The patient is apneic. Calculate the new rate and VT if desired PaCO2 is 65__________________
Calculate a new FIO2 if the desired PaO2 is 60_____________________________
The patient’s static compliance and dynamic compliance has improved, change the patient to SIMV
with appropriate settings
____________________________________________________________________________________
An ABG is drawn on the patient in SIMV with results: 7.32, 56, 110, 30
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How would you decrease PaO2 (besides FIO2)___________________________________
How would you decrease this patients PaCO2 ___________________________________
During SIMV, how would you know if the patient is improving?
_________________________________________________________________________
Suppose the patient has improved. Place the patient in CPAP with appropriate settings
______________________________________________________________________________
Group 3: Drager
A status asthmaticus patient arrives to the ER. The patient is a 16 year old male, 5’8 with bilateral
wheezes. The patient is unable to speak in full sentences, SpO2 90% on 100% NRM, HR 158, RR 42.
The patient is intubated before an ABG is drawn.
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Set the patient on initial settings including alarm limits and apnea
______________________________________________________________________________
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Perform a static compliance_____________________________________
Calculate Dynamic compliance___________________________________
Adjust ventilator to achieve a I:E ratio of 1:3
What therapy (besides the ventilator) would you recommend?___________________________
Would you suggest sedating and possibly paralyzing this patient? If so why or why not
_____________________________________________________________________________
An ABG is drawn. The patient is currently sitting on the ventilator BUR.
7.34, 55, 85, 30, 3.2
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The patient is apneic. Calculate the new rate and VT if desired PaCO2 is 35__________________
Calculate a new FIO2 if the desired PaO2 is 90_____________________________
Calculate the TCT and E-time_____________________
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The patient remains with tight bilateral wheezes, his dynamic compliance is low, what suggestions would
you make to improve this patients dynamic compliance? (5 points)
______________________________________________
The physician has decided that he would like the patients I:E ratio to be 1:5. Make the appropriate
changes required to achieve this I:E ratio (5 points)
___________________________________________________________
Calculate this patients expiratory time (5 points)
_____________________________________________________
A CBC is drawn; the patient has severe persistent asthma, with known allergies. The patient is suspected
to have had an allergic reaction leading to his current respiratory failure. Which WBC value would confirm
the presence an allergic response? (5 points)
__________________________________________________________________
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The patient has worsened. A pulmonary artery catheter has been placed. The patient requires PEEP
for his worsening compliance and oxygenation.
Based on the following information from the PEEP study below, choose the optimal PEEP level and
explain how you came to that decision.
PEEP (cmH2O)
Blood pressure (mmHg)
PaO2 (mmHg)
C.O. (L/min)
PCWP (mmHg)
5
117/80
43
4.2
10
10
110/70
65
4.0
11
15
115/75
90
4.4
12
20
90/65
103
3.3
18
On the optimal peep you chose, the following information is obtained: PIP 45 mmHg, Plateau pressure
29 mmHg, tidal volume 650 mL, tubing compliance is 1, flow 60 L/min.
Calculate static compliance.
Two days later the patient is awake and alert and on the following settings: SIMV mode, Vt 650cc, rate 8
breaths per minute, PS 10 cmH2O, PEEP +5 cmH2O, FiO2 35%. AM ABG is as follows: pH 7.38, PaCO2 44
torr, PaO2 75 torr, HCO3- 24 mEq/L. The physician asks you to obtain weaning parameters.
List at least three parameters that you would obtain and state the values that indicate the patient is
ready for weaning.
It is determined that the patient ready to be weaned.
How would you recommend weaning this patient? Adjust the ventilator accordingly.
Group 4 (classroom)
Answer the following questions
1. How do you increase PaO2 on APRV without compromising PaCO2 removal?
2. How do you decrease PaCO2 removal on APRV and at the same time increase PaO2?
3. How would you increase PaO2 on APRV if CO2 removal was not a concern?
4. Describe how you would wean a patient on APRV.
5. Describe the process of ARDS development. How does it affect:
a. paO2/FIO2 ratio
b. A-a gradient
c. CaO2
d. Cardiac Output
e. PAP and CVP
f.
CXR
g. Work of breathing
h. Static compliance
6. What are the settings for PRVC?
7. What are the advantages of using PRVC?
8. What are the disadvantages of using PRVC?
9. When would you change a patient from PRVC to PC?
10. How would you ventilate a patient with (include mode, and breath type)
o
Status Asthmaticus
o
COPD exacerbation
o
ARDS
o
Intracranial bleed
o
Post op
11. When would you use volume support over PSV?
12. When would you use PC-IRV over APRV?
13. When would you use ATC?
14. What should you monitor while a patient is on HFV?
15. How does CRF and liver failure lead to respiratory compromise? Include labs