Flashcards in Tests Of Lung Function Deck (21):
WhAt is the tidal volume?
Volume in and out with each breath
What is the inspiratory reserve volume?
The extra volume that can be breathed over that at rest
What is the expiratory reserve volume?
Extra volume that can be breathed out over that at rest
What is the residual volume and can it be measured with spiratorerry
This is the volume remaining after maximal expiration, and therefore cannot be measured with spirotmetert, but is important because it contributes to the total lung capacity
What is the vital capcity of the lungs?
Measured from max inspiration to max expiration, and is the biggest breath that can be taken and therefore often changes in disease- about 5l in a typical adult TV + ERV
What is the inspiratory capacity?
Biggest breath tathat can be taken from the resting expiratory level which is the lung volume at the end of quiet expiration and is typically 3L
What is the functional capcity?
Volue. Of the air in the lungs at the resting expiratory levels, and is typically about 2L but is affected by a number of factors ERV + RV
What is the total lung capacity?
The volume of gas in the lungs at the end of maximal inspiration
What are some of the factors that influence the vital capcity?
Inspiration- the compliance of the lungs and the force of inspiratory muscles, in expiration the airway resistance which increases as expiration proceeds,
What are some of the features of single breath spirometery?
Patients fills their lungs, breathes out as far and as fully as possibly, and the volumes are measured by the detector over time and measures how fast the air is breathed in and out
What is a vitalograoh trace?
A plot of the volume expired compared to the time, initial rapid rise tails to a plateau. And the forced vital capacity is the maximum capacity that can be expired from full lungs, and is typically 5L in adults
What is the FEV1.0?
The volume expired in the first second is affected by how quickly the air flow slows down, so decreases if the airways are narrowed and ratio between this and the FVC is very informative, normally >70%
What are some of the features of a obstructive pattern?
If the airways are narrowed the lungs will be easy to fill but the resistance will increase in expiration, so air will come out more slowly and FEV1.0 will be reduce but the FVC will be normal.
What is reversibility?
Spirotmetery performed before and after treatment, and if it is reversible this suggest asthma
What is a restricitive pattern?
Of the lugns are difficult to fill, for example are stiff, weak muscles, p, woth chest wall, they will start less full so the FVC will be reduced and the air will come out normally, so FEV1.0 will be less than 70% the FVC
What is the PEFR?
The peak expiratory flow rate, when the lung ps are full and there is little air expired and the airway are stretched, so resistance will be minimal, and the flow rate will be maximal
How doe tou see an obstructive pattern in a flow volume curve?
As lungs are compressed, more air is expired and the airways begin to narrow and the resistance is increased, and the flow rate falls and therefore the narrower the airways the more the flow rate falls
What happens in a restrictive pattern in a flow volume curve?
The flow volume curve is narrowed, and the shape is generally the same as normal, but flow is greater than normal at the comparable volumes.
What technique would you use to measure the serial dead space?
You would lose a nitrogen washout, as the last gas in the airways is the first gas out, and the subject takes one normal breath of oure oxygen, breaths out via a meter measuring the percentage of nitrogen, and initially only oxygen is expired,
And then a measure of oxygen and air and the containing nitrogen from the alveoli, and the volume expired at transition is the serial dead space
How do you assess the diffusion conductance?
A CO transfer factor