11.19: Pulm Review Flashcards
1
Q
What occurs to venous CO2 during exercise?
A
- Increase
- There is no change in arterial gases during exercise
2
Q
What is normal O2 consumption at rest?
A
250ml/min
3
Q
What is RQ
A
“Respiratory quotient”
- RQ = VCo2 / VO2, normally = .8
4
Q
Normal Tidal volume and respiratory rate?
A
RR = 10
TV = 500ml
**5 liters per minute
5
Q
What happens to arteriole gas levels during exercise?
A
- They always equilibrate in alveoli regardless of how hard you exercise or how short of breath you feel
- Alveoli is always fully oxygenating blood
6
Q
What happens to O2 in exercise?
A
- VO2 increases until O2 delivery cannot meet oxidative phosphorylation requirement
- Metabolic acidosis occurs after this to make more ATP
7
Q
What is the anaerobic threshold?
A
- HR at which lactate levels jump up greatly during exercise
- ATP demands cannot be met oxidatively, so now some must be done anaerobically
8
Q
What happens to tidal volume during exercise?
A
Increases
9
Q
Equation for max heart rate?
A
220 - age
10
Q
Does exercise cause hypoxemia?
A
- NO, unless you have lung disease
11
Q
What occurs in pulmonary fibrosis?
A
- Lung volume cannot increase with pressure increase
- Lungs have lost their compliance
12
Q
What is increased compliance?
A
- Small pressure change giving bigger than normal volume
- Loss of recoil seen in emphysema
13
Q
What occurs in emphysema?
A
- Loss of lung recoil / increased compliance
14
Q
How does asthma change compliance?
A
It doesnt
15
Q
What is responsible for difference between minute ventilation and alveolar ventilation?
A
Dead space
16
Q
What is dead space?
A
- Volume of inspired gas that does not partake in gas exchange: “Ventilated but not perfused”
17
Q
What is anatomic dead space?
A
- Portion of each breath that does not make it far enough into lungs
- Makes it into trachea but not lungs
18
Q
What is physiologic dead space?
A
- Gas that makes it to alveoli but is not exchanging gas as the alveoli it is in is not being perfused
- Occurs in zone 1 of lung: upper alveoli
19
Q
What is VD/Vt?
A
- Portion of each tidal volume that is wasted
- Dead space over tidal volume
- Normally is about 30%
20
Q
What happens to dead space in exercise
A
- Dead space decreases with increased flow to apex of lung
21
Q
What are diseases that can increase dead space?
A
- Volume depletion
- Pulmonary embolism
- Increased alveolar pressure from mechanical ventilation
- *Anything that will decrease perfusion to lung
22
Q
What are the consequences of increased dead space?
A
- Reduced CO2 elimination
- Increased work of breathing: dyspnea
23
Q
What happens to PaCO2 in panic attack?
A
- Decreases
- Your breathing rate increases to blow more off but you are not making more than normal
24
Q
What does increased dead space normally do to minute ventilation?
A
- Increases it to maintain normal Co2
- If CNS is not working Co2 will increase
25
What happens to CO2 in pulmonary embolism?
- PaCo2 decreases because body does so many things to compensate
26
What is hypercapnia?
Excessive Co2 in bloodstream, typically caused by inadequate respiration
27
What is WOB?
Work of breathing, person appears to be doing lots of work to get breath
28
What could lead to Normal PaO2, O2 saturation but decreased O2 content?
Colon cancer leading to anemia
29
What determines Hgb saturation?
- Driving pressure of O2 in the blood
| - How much Hgb is available for binding
30
What is O2 content?
- Total oxygen in blood including that bound to Hgb
31
At which Po2 is 50% saturation achieved?
- 27
| - Usually will be dead
32
What is normal venous PO2?
- 50% leading to saturation of 75%
33
What does arterial Po2 of 60 lead to?
- 90% saturation
| - Above PO2 60 minimal increase in saturation but decrease is drastic below 60
34
What is normal PaO2?
100
35
What would carbon monoxide poisoning lead to?
- Normal arterial PO2
- Decreased saturation since Carbon monoxide has higher affinity for Hgb
- Pulse Oximeter on finger cannot pick up this change
36
Can exercise decrease arterial oxygen saturation?
No
37
What is the alveolar arterial Oxygen gradient?
- What the O2 gradient between ideal alveolus and pulmonary capillaries should be
38
Equation for alveolar arterial oxygen gradient?
150 - (PaCo2/RQ) - PaO2
- PaCo2 / O2 is measured from blood gas
- RQ = .8
39
What is the normal Alveolar / arterial gradient?
- (Age / 4) + 4
| - As you age, gradient increases
40
When does A-a gradient increase?
- Most lung diseases
41
When is there hypoxemia with normal Aa gradient?
- High altitude
- Hypercapnia
- Decreases FIO2
42
What happens to vascular resistance with increased oxygen content in the lungs?
- Decreases
| - Vasoconstriction occurs on hypoxia
43
Why does arterioles constrict with low O2 content in alveoli?
- If there won't be much oxygen for blood to pick up, body does not want to send blood through that region so vasoconstriction occurs to prevent this
* **This is opposite to what happens in the rest of the body
44
What can hypoxia lead to in lungs?
- Pulmonary htn. as vasoconstriction increases
| - Cor pulmonale can occur
45
What happens at high altitude?
- PO2 decreases
- Begin to breathe more dropping CO2 leading to alkalosis
- Bicarb will also drop to compensate as kidneys will waste bicarb
46
What are we short of breath at altitude?
- Lower barometric pressure leading to less oxygen in the air
47
What will prolonged altitude exposure lead to?
- Increased EPO increasing hematocrit
- Increased 2/3 dpg leading to more O2 release at tissue
- Increased mitochondrial
* *Can lead to pulmonary hypertension
48
How to calculate acute change in PH from change in CO2
- For each 10 decrease in Co2, PH should increase .08
| - If change does not occur as expected something else is happening or kidney is responding
49
What can move hemoglobin curve right?
"Reduced affinity"
- Increased temp
- Increased 2/3 DPG
- Acidosis
- Altitude
50
What can move hemoglobin curve left?
"Increased affinity"
- Alkalosis
- Decreased temp
- Decreased 2/3 DPG
51
Does BP in arteries have any effect on pulmonary hypertension?
No
52
What can lead to pulmonary htn.?
1. Destruction of lung parenchyma: Emphysema
2. Decreased vasculature: PE
3. Left to right shunt
4. Hypoxic vasoconstriction
53
What is normal pressure in lungs?
25 mmhg
54
What can lead to hypoxemia with normal Aa gradient?
1. Hypoventilation
| 2. Altitude
55
What can lead to hypoxia with increased Aa gradient?
1. Shunt
2. VQ mismatch
3. Diffusion / perfusion mismatch
56
What occurs in VQ mismatch?
- Not ventilating alveoli but still perfusing them
57
Upper or lower lungs ventilated more?
- Lower
| - More perfusion in lower lungs too
58
What does VQ mismatch lead to?
- Mild hypoxia that responds to supplemental O2
59
What can cause VQ mismatch?
1. Asthma
2. COPD
3. Pulmonary Emboli
4. ILD
60
What is a shunt?
Movement of blood from venous to arterial without being oxygenated
61
What does shunt lead to?
- Severe hypoxia that does not respond to supplemental oxygen
62
What can lead to shunt?
1. Alveoli that are full of blood, pus, or water
2. Malformation of alveoli
3. Cardiac shunts
63
Two most common causes of hypoxia?
1. VQ mismatch
| 2. Shunt
64
Why is diffusion impairment not common?
- Blood is fully oxygenated in 25% of the time it spends in capillary
- Lots of margin for error
