Spirometry

Question 1

how is a spirometry done?

Answer 1

uses a spirometer to record changes in lung volume
results are plotted on a graph called a spirogram

Question 2

what are the waves in a spirogram?

Answer 2

inspiration produces an upward waveform deflection
expiration produces a downward deflection

Question 3

what is a power lab pneumotachometer?

Answer 3

an example of a spirometer
uses Flow rate to measure volume
air is breathed through a fine mesh to create a pressure difference across the mesh
this pressure difference is proportional to the flow rate
volume is then calculated as the integral of flow

Question 4

what is tidal breathing?

Answer 4

At rest, we breathe in a certain amount of air and expire the same amount of air. This repeats for as long as we’re at rest, and since it mimics the ebb and flow of the tides

Question 5

what is inspiratory reserve volume (IRV)?

Answer 5

This is the maximum volume above the tidal volume, that we can inspire into our lungs (approximately 3 L).

Question 6

what is tidal volume (Vt)?

Answer 6

This is the volume we inspire and expire during restful breathing. Normally the rate of breathing is 10–12 respiratory cycles per minute, and in adults VT is approximately 0.5 L.

Question 7

what is expiratory reserve volume (ERV)?

Answer 7

This is the maximum volume below the tidal volume, that we can expire from our lungs (approximately 1.5 L)

Question 8

what is residual volume (RV)?

Answer 8

This is the volume of air remaining in the lungs after a full expiration (approximately 1.2 L). We can never empty the lungs completely

Question 9

what is the inspiratory capacity?

Answer 9

This is all the air breathed in during a maximal inspiration at the end of a normal expiration. It is calculated by IRV + VT

Question 10

what is the expiratory capacity (EC)?

Answer 10

This is all the air breathed out in a maximal expiration after a normal inspiration. It is calculated by VT + ERV

Question 11

what is the functional residual capacity (FRC)?

Answer 11

This is the volume of air remaining in the lungs at the end of a normal expiration. It is calculated by ERV + RV [+]

Question 12

what is vital capacity (VC)?

Answer 12

This is all the air that can be expired from a maximal inspiration. It is calculated by IRV + VT + ERV

Question 13

what is total lung capacity (TLC)?

Answer 13

This is all the air that it is possible for the lungs to contain. It is calculated by IRV + VT + ERV + RV

Question 14

what is forced vital capacity?

Answer 14

the maximum volume of air that a person can forcibly expire after a maximal inspiration

Question 15

how can we calculate the forced expiratory volume in one second (FEV1)

Answer 15

we need both volume and time taken to transfer the volume

Question 16

what is FEV1?

Answer 16

-volume of air exhaled in the first second using maximal expiratory effort
-it represents more than 80% of the exhaled volume in a healthy young adult

Question 17

what should a health FEV1/FVC ratio be?

Answer 17

0.8 (80%) or more

Question 18

what could a low FEV1/FVC ratio indicate?

Answer 18

that an individual may have obstructive lung disease

Question 19

what are flow volume loops?

Answer 19

flow-volume loops are graphical representations of inspiratory and expiratory flows. They allow airflow to be measured for a specific lung volume. Flow-volume loops are normally plotted when a person expires as rapidly as possible following a maximal inspiration, but the same loop can be plotted for restful breathing or during exercise.

Question 20

why do we use flow volume loops?

Answer 20

airflow is not the same at every lung volume. To measure this, we plot lung volume against airflow. Doing so produces a flow-volume loop, as breathing is a continuous act

Question 21

what is an obstructive lung disease?

Answer 21

Individuals with an obstructive lung disease have difficulty breathing, due to narrowing of the airways or damage to the lung tissue. Asthma and chronic obstructive pulmonary disease (COPD) are two examples of obstructive lung diseases

Question 22

what Is a restrictive lung disorder?

Answer 22

Individuals with restrictive lung disorders have difficulty inspiring enough air. When the cause is a lung disease, the lung tissue is stiffened. This can result from damage to the lung walls, which produces scarring and decreases lung compliance. An example is pulmonary fibrosis

Question 23

how does a flow volume loop on someone with a restrictive disorder?

Answer 23

volume loop will be smaller but of a normal shape

Question 24

what can affect pulmonary parameter differences between volunteers?

Answer 24

Age, sex, body size, health, and physical condition can all influence a person’s pulmonary parameters

Question 25

what is the physiological significance of the FEV1/FVC ratio?

Answer 25

The ratio of FEV1 to FVC is an indication of an airway’s diameter. The higher the value, the faster air can flow through the airway. Therefore, the lower the resistance and the wider the airway

Question 26

Compared to normal breathing, how are FEV1 values affected by simulating airways obstruction?

Answer 26

For the simulated airways obstruction activity, the expiratory rate is slower. Therefore, FEV1 will be a smaller fraction of the total expired volume than in normal breathing. The decrease in FEV1 will result in a significantly lower FEV1/FVC ratio

Question 27

what is the criteria for acceptable spirometry?

Answer 27

free from artefacts
-cough
-glottis closure
-early termination or cut off
-effort not maximal throughout
-leak
-obstructive mouthpiece

good starts
-low extrapolated volume

satisfactory exhalation
-duration of at least 6s or a plateau in the volume time curve

between manoeuvre
Three acceptable spirograms should be obtained
 The two largest values of FVC and FEV1 must be within 0.15 L of each other