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RBF > Kolbe > Flashcards

Kolbe Flashcards

1
Q

What causes symptoms in COPD?

A

Chronic mucus hypersecretion - increased development of goblet cells and hypertrophy of mucus glands

Emphysema - destruction of lung perenchyma

Small airway inflammation.

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2
Q

What is the major central drive for respiratory rate?

A

CO2 levels in the blood.

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3
Q

Why does someone with COPD breath heavy?

A

To reduce the alveolar PACO2 to make them normocapnic. However, this doesnt help the O2 increase so they are hypoxemic. This has to do with the shape of the oxygen and CO2 dissociation curves.

When the disease progresses they are unable to undertake compensatory hyperventilation. This results in an increase of PaCO2. This causes a reduction in pH that is normlised by the kidneys.

Then you need to be careful because they become dependent on PO2 and not PCO2 for ventilatory drive and then giving 100% O2 can reduce ventilation drive. This further increases PCO2 and therefore acidosis.

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4
Q

Why might a patient be both red and blue?

A

Blue because of the hypoxaemia and red because of polycythemia. The patient develops polycythemia to increase the RBCs to increase haemoglobin. This is caused by an increase of EPO.

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5
Q

What is a right to left shunt?

A

When blood is shunted from the left side of the heart to the right side of the heart. This causes the blood in the left side of the heart to be mixed.

Give the patient 100% oxygen. If the arterial PO2 doesn’t get to the expected levels then it is a shunt.

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6
Q

How do you assess if your alveolar ventilation is sufficient?

A

Look at the partial pressure of CO2 in arterial blood.

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7
Q

How do you determine if the gas exchange is sufficient?

A

Look at the alveolar to arterial gradient. Aa gradient.

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8
Q

What is partial pressure?

A

The force exerted by a specific type of gas molecule in a given volume.

Or

Portion of the total pressure exerted by the presence of a single gas molecule

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9
Q

What is oxygen saturation?

A

It is the percentage of binding sites on haemoglobin that are occupied by oxygen.

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10
Q

What is oxygen concentration?

A

The amount of oxygen in volume percent that is present in the blood at any one moment.

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11
Q

What is hypercapnia really?

A

Alveolar hypoventilation

PaCO2 = 1/alveolar ventilation

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12
Q

What is the equation for minute ventilation?

A

V = Vt x f

V= Valveolar + V dead space

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13
Q

What is the equation to determine the alveolar partial pressure of O2?

A

PAO2 = FiO2 x (P(atm) - P(H2O)) - PACO2/RQ

The partial pressure of inspired O2 - the alveolar CO2 / per O2 produced (respiratory quotient)

Because CO2 is highly diffusible, therefore, PACO2 and PaCO2 are the same.

RQ is 0.8 (for normal diet)

Then you can calculate the Aa gradient.

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14
Q

What is the ratio of kPa to mmHg?

A

1 kPa to 7.5 mmHg

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15
Q

What is the issue for someone with pulmonary fibrosis who is exercising?

A

Problem of diffusion.

The blood will transit through the capillary faster and this will not allow someone with poor oxygen diffusion (due to the fibrosis) sufficient time for the oxygen to diffuse. He may have sufficient time for the oxygen to diffuse at rest, but when the transit time is decreased in exercise then there oxygen diffusion is impaired.

The diffusion of a gas depends on the area, the thickness (membrane and into the capillary) and the driving pressure of the gas (partial pressure; use CO). The capillary volume and haemoglobin is also important.

Draw this graph.

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16
Q

When trying to determine the driving pressure (partial pressure) of a gas in the alveolus, why use CO?

A

Because the downstream pressure is 0 because it is immediately taken up by haemoglobin.

17
Q

What are the important factors for gas diffusion?

A

The diffusion of a gas depends on the area, the thickness (membrane and into the capillary) and the driving pressure of the gas (partial pressure; use CO). The capillary volume and haemoglobin is also important.

18
Q

What are the conditions that cause an abnormal diffusion capacity?

A

Alveolar capillary block (pulmonary fibrosis)
Loss of diffusion surface (emphysema)
Problem with pulmonary capillaries.

19
Q

What is the definition of COPD?

A

Airflow limitation that is nor fully reversible. The airflow limitation is usually both progressive and associated with an abnormal inflammatory response of the the lungs to noxious particles or gases.

Caused by smoking in western countries.

20
Q

What happens to the blood in the left atrium when there is a shunt and what does this cause?

A

The mixing of the blood from the shunt (high CO2 and low O2) causes the mixed blood returning to the heart to have higher levels of CO2 and decreased O2.

The increased CO2 causes an increase in respiration. This only hyperventilates the non-shunt pathways.

This causes a normalisation of CO2 but the O2 remains low.

21
Q

Why does hyperventilation not increase the content of oxygen in the blood?

A

Oxygen dissociation curve.
Because the PAO2 in the lungs has alread achieved the peak concentration of O2. So increasing the PAO2 by hyperventilating can not further increase the content of O2 in the blood. (the haemoglobin are already saturated).

However, for CO2 it can cause a reduction in the content of CO2. This because the decrease in PACO2 can resut in a reduction of CO2 based on that curve.

As the disease progresses, they are unable to further increase the increased breathing. The CO2 rises a little bit. This reduces the pH which is compensated for by the kidneys.

22
Q

How can you tell if someone is on oxygen based on their bloods?

A

By working out the Aa gradient. The PaO2 has to be less than the PAO2.

23
Q

How can you tell the difference between venus admixture and Right-Left shunt?

A

Give the patient 100% oxygen. if the problem is in the ventilation perfusion ration, then they will regain normal PaO2. But if the problem is a shunt in the heart then this will not return the PaO2 to normal.

24
Q

Why does FEV1 increase when you exercise?

A

because the airways dilate from the increased production of catecholamines and reduced vagal tone

25
Q

What happens in airway hyperesponsiveness?

A

During exercise the airways dilate, but in hyperresponsivness, they then begin to contract

Contraction of the smooth muscle, and thickening of the airway mucosa

26
Q

Where do most of the lung diseases begin?

A

In the small airways. But because the resistance that occurs in the lungs of predominantly in the larger airways then you can have disease that doesn’t effect the lung tests.

27
Q

What are two ways to test lung function?

A

PEF and FEV1

PEF - cheap, but wide response range, effort dependent

FEV1 - not effort dependent

28
Q

What happens to the FEV1 and FVC in someone with obstructive lung disease?

A

Both decrease but the FEV1 is reduced more significantly than the FVC. The ratio of FEV1/FVC is reduced.

29
Q

What happens to breathing in obstructive lung disease?

A

Breath at much higher volumes. Air left in lungs.

This is because the recoil is worse so you keep the lungs inflated to where they recoil better. Keeps the airways open because of the reduced resistance.

However, the compliance (change in volume for a given change in pressure) is reduced at the higher volumes. This means that the work is increased because for a given change in pressure you get a smaller change in volume. Take smaller breaths.

30
Q

What causes SOB?

A

Increase in the work of breathing. Not usually related to hypoxaemia.

31
Q

How do you calculate the work of breathing?

A

Work = pressure x volume

32
Q

How is minute ventilation increase in the healthy?

A

Increase the tidal volume and the breathing rate.

In those with resistance disorders, they increase the rate but not the tidal volume. The consequence of this is that the ratio of dead space to alveolar ventilation is constant, whereas, if the tidal volume is increased then the ratio is lower.

33
Q

What is the pattern of breathing for someone with COPD and someone with pulmonary fibrosis?

A

COPD: Increase the volume to increase the elastic work of breathing and to decrease the resistive wok of breathing. Breath slow to reduce resistive work.

Pulmonary fibrosis: increase the rate of breathing to decrease the elastic work and increase the resistive work.

34
Q

What happens to the FEV1 and FVC in someone with pulmonary fibrosis?

A

FEV1 - decreased and FVC decreased: ratio the same

Reduced residual volume. Higher flow of exhalation because of higher elastic recoil.

Draw these diagrams for both COPD and PF. In test

35
Q

What are the three broad things that can cause hypercapnia when there is an issue?

A

Respiratory drive

Neuromuscular transmission

Load (work)

RBF (9 decks)

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