Introduction to spirometry

Question 1

What is a spirometry test?

Answer 1

-measures ventilatory function by measuring the volume of air which can be breathed out and how quickly you can breathe it out.

Question 2

What are some general indications for spirometry?

Answer 2

-medical diagnosis
-surgery
-disability evaluation
-research

Question 3

What are some medical diagnosis indications for spirometry?

Answer 3

-measures effect of disease on respiratory function
-evaluate signs, symptoms or lab findings
-physical fitness, selection or evaluation in health and disease
-reassure patient and physician
-follow the course of disease affecting respiratory function

Question 4

What are some surgical indications for spirometry?

Answer 4

-pre- op risk evaluation for anaesthetic and surgery
-post-op assesment of surgery, in particular thoracic surgery

Question 5

What are some indications for spirometry based on disability evaluation?

Answer 5

-industrial medical assessment
-government compensation laws
-personal injury lawsuit
-other legal purposes( failure to provide a breath test)

Question 6

What are some indications for spirometry in regards to research?

Answer 6

-clinical trials
-epidemiological studies

Question 7

What are the units of volume and flow?

Answer 7

volume - litres
flow- litres/second or litres/minute

Question 8

Whats the equation that links flow, volume and time?

Answer 8

flow= volume/time

Question 9

What are the lung subdivisions?

Answer 9

volumes- VT, ERV, IRV, RV
capacities-IC, VC, TLC
units-litres

Question 10

Define tidal volume

Answer 10

the volume of gas expired or inspired during one breathing cycle

Question 11

Define inspiratory capacity (IC)

Answer 11

the maximum volume of gas which can be inspired from the position of functional residual capacity (FRC)

Question 12

Define inspiratory reserve volume (IRV)

Answer 12

the maximum volume of gas which can be inspired from the position of end inspiratory tidal volume

Question 13

Define functional residual capacity (FRC)

Answer 13

the volume of gas in the lungs and airways at the end of a tidal expiration

Question 14

Define expiratory volume (ERV)

Answer 14

the volume of gas which can be maximally expired from the postion of FRC

Question 15

Define residual volume (RV)

Answer 15

The volume of gas remaining in the lungs and airways at the position of full expiration

Question 16

Define total lung capacity (TLC)

Answer 16

the volume of gas in the lungs and airways at the position of maximal inspiration

Question 17

What measurements are made during spirometry?

Answer 17

-FEV1 (forced expiratory volume in 1 second
-FVC (forced viral capacity)
-FEV1/FVC%
-Peak expiratory flow (PEF)
-relaxed vitall capacity (RVC)

Question 18

what is relaxed vital capacity?

Answer 18

measures the change in the volume of air in the lungs from expiratory relaxed vital capacity or inspiratory relaxed vital capacity

exp-from TLC to residual volume

insp-from residual volume to TLC

measured in litres

Question 19

Describe the forced expiratory manoeuvre

Answer 19

-patient breathes out as hard and as fast as possible and continues until they are completly empty

-spirogram
-flow volume curve

Question 20

Define FEV1

Answer 20

volume of gas expired during the first second of expiration is also measured

-measured in litres

Question 21

Whats a spirogram?

Answer 21

plots exhaled volume against time during a forced expiratory effort

-graph starts at a position of maximum inspiration

Question 22

How to calculate FEV1/FVC% ratio?

Answer 22

-calculate FEV1 as a percentage of the FVC

• how much of the vital capacity can you breathe out in the first second

-in healthy subjects the FEV1/FVC% will be over 70%

Question 23

FEV1/FVC% ratio equation?

Answer 23

FEV1/FVC% = measured FEV1/ Measured FVC% all x100

Question 24

What is the flow volume loop?

Answer 24

information from the same test but displayed in a different way

-measures expiration and inspiration

Question 25

Describe what the flow volume loop graph looks like

Answer 25

-almost right angle triangle
-sharp rise at start
-sharp point at peak flow
-steady decline in flow from peak flow to RV

Question 26

Define PEF/ peak expiratory flow test?

Answer 26

the maximum flow that can be achieved during a forced expiration from TLC

-reported in L/min or L/sec

Question 27

What can you not measure on a flow volume loop?

Answer 27

-FEV1

Question 28

What is FEF/ forced expiratory flow?

Answer 28

the maximum flow achievable during a maximum forced expiratory manoeuvre when x% of the FVC has been exhaled

Example FEF25% is the maximum flow rate achievable when 25% of the FVC has been exhaled

Question 29

Describe what happens during a PEF test

Answer 29

-PEF is achieved within the first 100 milliseconds of a forced expiration

-represents an index of resistance to flow through larger airways and bronchioles

-effort dependent

Question 30

How are lung volume measurements standardized?

Answer 30

-charles law states that a given quantity of gas held at a constant pressure will have a volume directly proportional to the absolute temperature

-as temperature increases, volume increases to

Question 31

Whats the link between temperature and spirometry?

Answer 31

-patient breathes out = expired gas cools

-temp of exhaled gas falls from body temp to temp within spirometer

-Charles law states the volume of gas becomes smaller

-as air cools, water vapour within condenses

-to standardize results all lung function volumes and flows are corrected to body temp and barometric pressure, saturated with water vapour conditions (BTPS)