Lung Function Testing and Lung Imaging Flashcards
What limits max inspiration?
The compliance of the lung and force of inspiratory muscles: diaphragm and external intercostal muscles
What limits max expiration?
Increasing airway resistance
What is vital capacity? What test can you do to measure it, and what other value will you find out from this test?
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
When will patients with a restrictive deficit experience difficulty? What “restrictive” issues might they have that generates this?
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
When will patients with an obstructive deficit experience difficulty? Name some examples
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
What does PEFR stand for?
How will it change in obstructive and restrictive disease?
Axes: y=flow, x=volume expired
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
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?
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
What device is used to measure PEFR?
Peak flow metre
How would you measure residual volume? How and why does it work?
Helium dilution: used as helium is not soluble in blood, so it will not enter the circulatory system
- Have patient breathe in a known volume of helium
- Helium will mix with the air already in the lungs and become dilute
- The extent that helium becomes dilute tells you how much residual air is in the lungs
How would you measure serial dead space? How does it work?
Nitrogen washout
- Subject takes normal breathe of pure oxygen
- 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
- 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
What can Nitrogen washout indirectly measure?
How will the line measuring % Nitrogen against Volume expired appear?
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
What defines diffusion conductance and how can you measure it? What do you need to know?
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
What is a normal ratio of FEV1.0/FVC?
70%
What does the ratio between Residual volume and total lung capacity tell you?
If the patient is trapping air in their lungs, and if the airways are so narrow that air cannot get out
What does CO conductance tell you?
If there’s a problem with gas exchange across the alveolar membrane
What is the golden standard for a chest X ray?
PA view: Shows a more accurate cardiac size and the scapula is rotated out of the way (if patient can raise arms)
When is an AP view used?
If the patient is too ill to stand
How does a ___ appear on an X ray?
a) effusion
b) air
Effusion: Opacity indicates fluid
Air/ Pneumothorax: darker areas indicate excessive air
What major vessel is near the R hilum?
The R pulmonary artery
What forms the R and L heart border?
R heart border: R atria
L heart border: L ventricle
Why is the L hilum higher than the R hilum?
What can be inferred if the R hilum is higher?
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
What should you normally see on an X ray in lung tissue?
Blood vessels
Where is the cardiophrenic angle?
Where is the costophrenic angle?
Cardiophrenic: angle between the heart and the diaphragm
Costophrenic angle: where the diaphragm meets the ribs
Name a sign of the following lobar collapses: RUL: RML: RLL: LUL: LLL:
RUL: Triangular sign RML: NO R heart border visible RLL: Triangle sign LUL: NO L heart border visible LLL: Triangle sign
What does ‘white out’ indicate?
What else can shift as a consequence of this?
Total lung collapse
The trachea and mediastinum may be pulled towards the side of the collapse if air accumulates
What does a clinician and a radiologist mean when they say consolidation?
Clinician: Infective, i.e pneumonia
Radiologist: pattern of opacification, fluffy and cloud like, hard to see blood vessels
What does battwing indicate? Name one likely diagnosis
Bi-lateral (both lung) consolidation, TB
What is a spacy occupying lesion?
What can be inferred when it is solitary, or multliple?
Lung mass/tumor
Solitary: primary tumour
Multiple: metastasis
What indicates a pleural effusion on an x ray?
A dense opacification with a “meniscus” upper margin: concave upper margin.
What can be indicative of a patient with a metallic clip on an x ray?
Indicates previous major lung surgery
How would you identify cardiomegaly?
If the heart exceeds 50% of the cardiothoracic ratio
What 2 ways can air get into the pleural space?
Through a hole in the chest wall or from a hole in the lung
What do ‘angel wings’ on an x ray indicate? What is a possible cause?
Dense pleural calcification, asbestos exposure
Define pneumoperitoneum? How would you recognize this on an X-ray?
Hole in the abdomen, dark crescent shadows underneath the hemidiaphragm
Describe the appearance of a ‘cavity’ on an X ray, name 2 things the cavity could be
Cavity appears as a round white circle with a hole in the middle, could be a tumour or an infection (e.g; TB)
What is one likely diagnosis of a bilateral pleural effusion?
Cardiac failure
What’s the difference between a consolidation and an effusion?
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.
