Lung Function Tests

Question 1

what is the function of the respiratory system

Answer 1

• The flow of air in and out of the respiratory system

- Devilry of air to the alveoli where gas exchange takes place

Question 2

what does spirometry measure

Answer 2

Assess lung function tests

Measure both expired and inspired air

Question 3

what are the basic 3 related measurements of spirometry

Answer 3

volume
time
flow

Question 4

what are the positives of spirometry

Answer 4

objective
non-invasive
sensitive to disease

Question 5

how should the patient be positioned in spirometry

Answer 5

• sit upright
• feet flat on the floor with legs uncrossed
• no use of abdominal muscles for leg position
• loosen tight fitting clothing, if clothing is too tight this can give restrictive pictures on spirometry

Question 6

what is the technique that should be used in spirometry

Answer 6

• deep breath taken in why still using the mouthpeice
• followed by a further quick full inspiration
• deep breath can be taken in then the mouth is placed tightly around the mouthpiece before a full expiration is performed
• patient asked to completely empty their lungs then take a quick full inspiration followed by a full expiration

Question 7

what is the quality of spirometry

Answer 7

• have to have an explosive start
• manoeuvre was performed with a maximal inspiration and expiration
• no glottis closure or cessation of airflow occurred
• no coughs
• manoeuvre should meet the end of test criteria (exhaling for 6s with 50ml being exhaled in the last 2s)

Question 8

define tidal volume

Answer 8

this is the volume of air you move into and out of the lungs during rest subconsciously,

Question 9

define inspiratory capacity

Answer 9

maximum volume of air inout and out of the lungs in a single respiratory cycle

Question 10

define forced vital capacity

Answer 10

volume of air that you breath out as hard and fast as possible after the deepest possible breath

Question 11

define inspiratory reserve volume

Answer 11

volume of air you can draw into your lungs

Question 12

define expiratory reserve volume

Answer 12

volume of air you can expel from your lungs

Question 13

define residual volume

Answer 13

volume of air that remains in the lungs even after maximal exhalation

Question 14

how do you work out forced vital capacity

Answer 14

inspiratory reserve capacity + tidal volume + expiratory reserve volume

Question 15

what is the PEF

Answer 15

maximal airflow you can achieve during the expiration phase

Question 16

what are the main determinants in determining the FVC

Answer 16

• Age
• Height
• Sex
• Race

Question 17

the taller you are the…

Answer 17

greater the lung function

Question 18

as you age…

Answer 18

your lung function declines

Question 19

what happens to the PEF in asthma

Answer 19

• it is decreased

Question 20

why is it important to repeat lung function tests

Answer 20

• lung function might be fine one day and change the next day

Question 21

asthmatics have xxx lungs

Answer 21

hyper inflated lungs

Question 22

what happens to the volume flow graph in obstructive lung disease

Answer 22

• hyperinfalted lungs so there is.a greater residual volume then someone with no obstructive comprise therefore the graph shifts to the left

Question 23

what happens to the volume flow graph in restrictive lung disease

Answer 23

– loss of lung capacity, the residual volume is significantly less than with someone with no respiratory comprise, the volume that they are able to generate in forced vital capacity is also less, thus the loop shifts to the right

Question 24

what is a normal FEV1/FVC ratio

Answer 24

• FEVI/FVC is a ratio of Forced Expiratory Volume in 1 sec & Forced Vital Capacity
• Values above 70-80% = normal. Age/gender/height adjusted
• Airflow limitation (e.g. Asthma) : ↓FEV1/FVC

Question 25

describe the difference between FEV1/FVC in asthmatic and COPD

Answer 25

- Although FEV1 is reduced FV is still the similar to someone with no respiratory compromise - COPD is different as they usually have obstructive airflow that is persistent

Question 26

what is the limitations of spirometry

Answer 26

* Values above 70-80% = normal. Age/gender/height adjusted * Airflow limitation (e.g. Asthma) : ↓FEV1/FVC * Incorrect in some populations = Asian communities * Misdiagnosis risk? Age-related decline in lung function not because they have obstructive lung disease - therefore the solution is the 95th percentile for a population - these limits lower normality

Question 27

what does DLCO/TLCO measure

Answer 27

- Measures how efficient lungs are at exchanging gases | - Ability of lungs to transfer gas from inhaled air to red blood cells

Question 28

how does the DLCO work

Answer 28

- Diffusing capacity of the lungs for CO (DLCO) – used at 0.3% - Haemoglobin has a higher affinity for carbon monoxide then oxygen

Question 29

what is the technique for DLCO

Answer 29

- Single breath hold technique - Unforced maneous empties the lungs, take a rapid inhalation of CO/helium to total lung capacity, breath hold for 10 seconds and then unforced exhalation for less than 4 seconds - The sample is exhaled breath

Question 30

what does DLCO stand for

Answer 30

diffusing capacity of the lungs for carbon monoxide

Question 31

what are the two important parameters that determine the DLCO

Answer 31

- Lung surface area available for gas exchange | - Rate of capillary blood CO uptake

Question 32

how do you work out the DLCO

Answer 32

Lung surface area available for gas exchange (Va) X rate of capillary blood CO uptake (Kco)

Question 33

Why in restrictive lung disease does the DLCO decrease

Answer 33

- ILD: ↓DLCO primarily due to ↓Kco (NB ILD: Fibrosis of Interstitium)

Question 34

what is DLCO useful for

Answer 34

- Useful for early stage ILD detection before substantial reduction in lung volumes

Question 35

what are the limitations of the DLCO

Answer 35

Falsely reduced in individuals who fail to inspire to TLC (technique) and Significant variation

Question 36

describe what exercise tests test assess

Answer 36

- Assess how much exercise a patient is able to manage - Assess benefit of extra oxygen to help with daily activities - Assess pre-operative fitness - Part of a rehabilitation programme

Question 37

name some exercise tests

Answer 37

6 minute walk shuttle walk cardiopulmonary exercise

Question 38

describe how the 6 minute walk works

Answer 38

- Walk up and down a flat route for 6 minute - Asses breathless pre and post test - Blood oxygen saturation levels recordered

Question 39

describe how the shuttle test works

Answer 39

- Assess distance and speed without taking rest (bleep test)

Question 40

describe how the cardio-pulmonary exercise test works

Answer 40

- Assess pre-operative fitness/undiagnosed shortenss of breath/poor exercise tolerance cycle ergometer/treadmill - Increase resistance Measures - Oxygen consumtion - ECG - SpO2

Question 41

how do you work out - vital capacity - end respiratory volume - total lung capacity - inspiratory capacity - functional residual volume - expiratory reserve volume

Answer 41

- vital capacity = is calculated by adding the inspiratory reserve volume, the tidal volume and the expiratory reserve volume (IRV + VT + ERV) - end respiratory volume = measured, total lung capacity (TLC) - total lung capacity = is calculated by adding the inspiratory reserve volume, the tidal volume, the expiratory reserve volume and the residual volume (IRV + VT + ERV + RV) - inspiratory capacity = is calculated by adding the tidal volume and the inspiratory reserve volume (VT + IRV) - functional residual volume = FRC) is calculated by adding the expiratory reserve volume and the residual volume (ERV + RV) - expiratory reserve volume = (ERV) is a measured value and cannot be calculated

Question 42

what is the FEV1/FVC in obstructive and restrictive

Answer 42

- raises in restrictive - The lungs could be normal The ratio may be unaffected whilst both the FEV1 and the FVC have decreased, as occurs in restrictive lung disease - decreases or remains the same in obstructive This indicates obstructive lung disease The value FEV1 decreases and therefore the ratio decreases