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Crit Care > Peep & O2 & CO2 > Flashcards

Peep & O2 & CO2 Flashcards

1
Q

What happens to PaCO2 when you increase your minute ventilation?
A. The PaCO2 will increase
B. The PaCO2 will decrease

A

B. The PaCO2 will decrease when you increase your minute ventilation (Ve)

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2
Q

What effect does decreasing your alveolar ventilation have on PaCO2?
A. The PaCO2 will increase
B. The PaCO2 will decrease

A

A. The PaCO2 will increase when your alveolar ventilation is decreased (VA)

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3
Q

What is the formula for computing alveolar ventilation?

A

VA=(0.863 x VCO2)/PaCO2

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4
Q

What are the factors that affect the partial pressure of PaCO2?

A

VCO2 & VA

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5
Q

If you know your minute ventilation how do you find your alveolar ventilation, what is the formula?

A

VA = VE - VD

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6
Q

What two variables make up minute ventilation and affect PaCO2 levels?

A

Vt & F

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7
Q

What two factors affect f & when adjusted can impact the PaCO2?

A

Ti & Te

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8
Q 
When you have a condition of respiratory acidosis what does this mean in terms of your alveolar ventilation?
A.  Vd is elevated
B.  Frequency is set too high
C.  VA is inadequate
D.  VA is excessive
A

C. Respiratory acidosis means that alveolar ventilation is inadequate

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9
Q 
When you have a condition of respiratory alkalosis what does this mean in terms of your alveolar ventilation?
A.  Vd is elevated
B.  Frequency is set too high
C.  VA is inadequate
D.  VA is excessive
A

D Respiratory alkalosis means that alveolar ventilation is excessive

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10
Q

When setting your Vt for a ventilated patient it is important that plateau pressure is kept below what level?

A

30 cmH2O

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11
Q

When the condition of respiratory alkalosis is present what is one of the main causes of this abnormal condition?

A

Hypoxia with compensatory hyperventilation which causes the PaCO2 to be low

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12
Q

Name the four types of hypoxia.

A

Hypoxemia Hypoxia
Anemic Hypoxia
Circulatory Hypoxia
Histotoxic Hypoxia

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13
Q 
If your patient is breathing a rate of 20 breaths per minute and we change his rate from 16 to 16 breaths per minute what changes should you see in your ABG?
A.  Your PaCO2 will increase
B.  No changes to your PaO2 will result
C.  You will see a decrease in pH
D.  You will see your FIO2 increase
A

B. Nothing Changes

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14
Q

If you have an increase in your dead space what effect will that have on your CO2?

A

The CO2 will increase

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15
Q

Name a condition or disease abnormality which will increase your dead space?

A

Pulmonary Emboli

Low cardiac output

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16
Q

Name some methods of reducing mechanical dead space?

A

Trach the patient
Cut the ET tube
Using a low compliance circuit

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17
Q

In the volume mode what would you need to change to increase your minute ventilation?

A

Vt or F must be increased to improve minute ventilation

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18
Q

Factors that can alter during PaCO2

mechanical ventilation include?

A

total ventilation,
dead space and
CO2 production.

19
Q

A value greater than 45 torr indicates
A. hypoventilation
B. Hyperventilation

A

A. Hypoventilation

20
Q

A value less than 35 torr indicates
A. Hypoventilation
B. Hyperventilation

A

B. Hyperventilation

21
Q

In COPD the patients COPD is about _______ torr or based on their last hospital stay.

A

50 torr

22
Q

Regardless of the mode of ventilation Ve must be ______ to lower PaCO2
A. Increased
B. Decreased

A

VE must increased be to lower PaCO2

23
Q 
What can cause air trapping?
1.  Reduced pulmonary perfusion
2.  High I:E ratio such as 3:1
3.  Uneven distribution of ventilation
4.  Laminar flows
A.  1, 2
B.  1,2,3
C.  1,2,4
D.  All of the above
A

C. 1, 2, 3

24
Q

If you have air trapping how can you fix this?

A

Increasing flow which shortens Ti allowing more exhale time;

Decreasing I:E

25
Q

What is your normal ratio of dead space to tidal volume?

A

Vd/Vt normal value is .2 - .4

Critical value is above .7

26
Q

When ventilating an ARDS patient sometimes it becomes impossible to maintain a normal PaCO2 so we will allow what to occur? Why?
A. Permissive hypocapnia
B. Permissive hypercapnia

A

B. Permissive hypercapnia–protective strategy that avoids lung overdistention and injury to the lung; PaCO2 levels are allowed to rise above 50; the critical ph value is 7.25

27
Q

Increases in PaCO2 and decreases in pH cause what type of shift to the curve?
A. Right Shift
B. Left Shift

A

A Right Shift of Curve

28
Q

T or F: It is desirable to utilize sedation & paralytics during permissive hypercapnia.

A

True

29
Q

CO2 is a powerful _________ of cerebral vessels.
A. Vasodilator
B. Vasoconstrictor

A

A. Vasodilator; increasing CO2 can cause cerebral edema and increased ICP so it should not be used on head trauma patients;

30
Q 
Permissive hypercapnia has been shown to cause these effects:
A.  decreased myocardial contractility
B.  Arrhythmias
C.  increased sympathetic activity
D.  increased cardiac output
E.  Pulmonary hypertension
A

All of the above

31
Q

T or F: Permissive hypercapnia has been shown to call lower cardiac output

A

False; it is shown to cause increased cardiac output

32
Q

T or F: When using permissive hypercpania the systemic blood pressure may show normal even when cardiac output is increased.

A

True

33
Q

Name 5 methods that can be used to improve ventilation.

A 
Optimize Vt
Increase frequency
Increase spontaneous Vt 
Reduce Mechanical dead space
High frequency jet or ascillatory vent
34
Q

How can you increase a patients spontaneous VT?

A 
PSV, 
nutritional support, 
Using the largest ET tube, 
medications such as aminophylline which strengthens muscles, 
TRC, 
reconditioning of respiratory muscles
35
Q

What is the formula you can use to calculate a certain PaCO2 from a desired min ventilation?

A

Desired PaCO2 x Desired MV= Current PaCO2 x Current MV

36
Q

When analyzing your flow in pressure ventilation to determine the best setting; Flow should normally be _____ % from the peak pressure.

A

25%

37
Q

If you find your flow is not sufficient and is ending before lung filling stops what would you do?

A

Increase the I time; your I time is too short;

38
Q

If you witness a break or no flow condition at baseline what does this mean?

A

Your I time is too long, need to shorten Ti

39
Q

How would you compute your desired pressure if you have a desired VT and know you static compliance in pressure mode?

A

Desired Pressure = Desired Vt/ Static Compliance

40
Q

If you are in pressure mode and you make a change to pressure what else must you address to keep your same pressure gradient?

A

You must go back & adjust your Ti to its previous value

41
Q

When you have a low cardiac output what effect will this have on ventilation?
A. Ventilation will increase
B. Ventilation will decrease
C. No Change

A

C. No change; ventilation remains the same

42
Q

What effect does low cardiac output have on the lungs?

A

Low perfusion

43
Q

When you use high peep what effect does that have on pulmonary blood flow?

A

Pulmonary blood flow may decrease

44
Q 
If you have a patient with traumatic brain injury what protective strategy would you use?
A.  Intentional Hypoventilation
B.  hypercapnia
C.  Intentional hyperventilation
D.  None of the above
A

C. Intentional hyperventilation is used with traumatic head injury to cause vaso constriction

Crit Care (8 decks)

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