Lung Function Testing and Lung Imaging

Question 1

What limits max inspiration?

Answer 1

The compliance of the lung and force of inspiratory muscles: diaphragm and external intercostal muscles

Question 2

What limits max expiration?

Answer 2

Increasing airway resistance

Question 3

What is vital capacity? What test can you do to measure it, and what other value will you find out from this test?

Answer 3

Vital capacity is the max inspiration- expiration, and can be measured by single Breath spirometry: One large and fast expiration. This will also tell you the FEV1.0: amount of air exhaled in the first second

Question 4

When will patients with a restrictive deficit experience difficulty? What “restrictive” issues might they have that generates this?

Answer 4

Patients with a restrictive deficit have more problems on inspiration, meaning their lungs are likely not compliant or there is difficulty contracting their diaphgram. Patients may have fibrosis, obesity, pregnant, TB, or muscular dystrophy

Question 5

When will patients with an obstructive deficit experience difficulty? Name some examples

Answer 5

Patients with obstructive deficit will experience more issues on expiration (although may become so severe that they will have issues on inspiration as well) due to airways being so compressed their resistance becomes too high (this is why they have a reduced FEV1).

E.g: asthma, COPD, chronic bronchitis

Question 6

What does PEFR stand for?
How will it change in obstructive and restrictive disease?

Axes: y=flow, x=volume expired

Answer 6

Peak expiratory flow rate

Obstructive: you will see “scalloping”: expiratory flow decreases rapidly and then tapers off (looks like a ‘inward curve’)

Restrictive: Less volume can enter the lungs: looks like a smaller mountain inside the PEFR

Question 7

If there is an abnormal PEFR where in the resp tract would you assume the problem is?

If there is an abnormality later in the flow volume curve where would you assume the problem is?

Answer 7

The intial airflow of the lungs is affected most by the max resistance in larger airways: so an abnormal PEFR is likely due to the trachea

An abnormality later in the flow volume curve indicate problems in small airways

Question 8

What device is used to measure PEFR?

Answer 8

Peak flow metre

Question 9

How would you measure residual volume? How and why does it work?

Answer 9

Helium dilution: used as helium is not soluble in blood, so it will not enter the circulatory system

1. Have patient breathe in a known volume of helium
2. Helium will mix with the air already in the lungs and become dilute
3. The extent that helium becomes dilute tells you how much residual air is in the lungs

Question 10

How would you measure serial dead space? How does it work?

Answer 10

Nitrogen washout

1. Subject takes normal breathe of pure oxygen
2. Space next to the alveoli will have a mixture: The oxygen you’ve just breathed in, and the functional residual capacity which already has Nitrogen in it
3. Patient breathes out slowly: Initial air that comes out has will have no N as that air hasn’t reached the alveoli = the serial dead space
   * Measure how much of the the air the patient expires has NO Nitrogen

Question 11

What can Nitrogen washout indirectly measure?

How will the line measuring % Nitrogen against Volume expired appear?

Answer 11

Idirectly measures ventilation perfusion matching: as if there is a VPM problem, different parts of the lungs will have different mixtures of gases.

Line will wiggle, as air is coming from parts of the lung that has both good and bad exchange so the % of N will vary

Question 12

What defines diffusion conductance and how can you measure it? What do you need to know?

Answer 12

Diffusion conductance: how easily gases (e.g; oxygen) cross the alveolar membrane
Pressure Difference = Amount of gas X Resistance
Need to know the pressure of oxygen in alveoli and venous blood, and how much oxygen is being taken up. How to measure pO2 in venous blood without inserting a catheter into the pulmonary artery: KNOW that gases move passively

Use CO: as it binds tightly to Hb and is released slowly, so it doesn’t exert a partial pressure (can assume pCO in the blood is 0).

Measure gas mixture with a small [CO], the pressure of the CO in alveoli and how much CO moves into the blood

Question 13

What is a normal ratio of FEV1.0/FVC?

Answer 13

70%

Question 14

What does the ratio between Residual volume and total lung capacity tell you?

Answer 14

If the patient is trapping air in their lungs, and if the airways are so narrow that air cannot get out

Question 15

What does CO conductance tell you?

Answer 15

If there’s a problem with gas exchange across the alveolar membrane

Question 16

What is the golden standard for a chest X ray?

Answer 16

PA view: Shows a more accurate cardiac size and the scapula is rotated out of the way (if patient can raise arms)

Question 17

When is an AP view used?

Answer 17

If the patient is too ill to stand

Question 18

How does a ___ appear on an X ray?

a) effusion
b) air

Answer 18

Effusion: Opacity indicates fluid

Air/ Pneumothorax: darker areas indicate excessive air

Question 19

What major vessel is near the R hilum?

Answer 19

The R pulmonary artery

Question 20

What forms the R and L heart border?

Answer 20

R heart border: R atria

L heart border: L ventricle

Question 21

Why is the L hilum higher than the R hilum?

What can be inferred if the R hilum is higher?

Answer 21

As the L pulmonary artery is usually higher than the R pulmonary artery.

If the R hilum is higher, means something is pulling the R hilum up or pulling the L hilum down

Question 22

What should you normally see on an X ray in lung tissue?

Answer 22

Blood vessels

Question 23

Where is the cardiophrenic angle?

Where is the costophrenic angle?

Answer 23

Cardiophrenic: angle between the heart and the diaphragm

Costophrenic angle: where the diaphragm meets the ribs

Question 24

Name a sign of the following lobar collapses:
RUL:
RML:
RLL:
LUL:
LLL:

Answer 24

RUL: Triangular sign 
RML: NO R heart border visible 
RLL: Triangle sign 
LUL: NO L heart border visible
LLL: Triangle sign

Question 25

What does ‘white out’ indicate?

What else can shift as a consequence of this?

Answer 25

Total lung collapse

The trachea and mediastinum may be pulled towards the side of the collapse if air accumulates

Question 26

What does a clinician and a radiologist mean when they say consolidation?

Answer 26

Clinician: Infective, i.e pneumonia
Radiologist: pattern of opacification, fluffy and cloud like, hard to see blood vessels

Question 27

What does battwing indicate? Name one likely diagnosis

Answer 27

Bi-lateral (both lung) consolidation, TB

Question 28

What is a spacy occupying lesion?

What can be inferred when it is solitary, or multliple?

Answer 28

Lung mass/tumor
Solitary: primary tumour
Multiple: metastasis

Question 29

What indicates a pleural effusion on an x ray?

Answer 29

A dense opacification with a “meniscus” upper margin: concave upper margin.

Question 30

What can be indicative of a patient with a metallic clip on an x ray?

Answer 30

Indicates previous major lung surgery

Question 31

How would you identify cardiomegaly?

Answer 31

If the heart exceeds 50% of the cardiothoracic ratio

Question 32

What 2 ways can air get into the pleural space?

Answer 32

Through a hole in the chest wall or from a hole in the lung

Question 33

What do ‘angel wings’ on an x ray indicate? What is a possible cause?

Answer 33

Dense pleural calcification, asbestos exposure

Question 34

Define pneumoperitoneum? How would you recognize this on an X-ray?

Answer 34

Hole in the abdomen, dark crescent shadows underneath the hemidiaphragm

Question 35

Describe the appearance of a ‘cavity’ on an X ray, name 2 things the cavity could be

Answer 35

Cavity appears as a round white circle with a hole in the middle, could be a tumour or an infection (e.g; TB)

Question 36

What is one likely diagnosis of a bilateral pleural effusion?

Answer 36

Cardiac failure

Question 37

What’s the difference between a consolidation and an effusion?

Answer 37

An effusion is an accumulation of fluid in the pleural space. A consolidation may be fluid, but it’s inside your lung and can’t move when you change positions.