Lecture 10 - Spirometry

Question 1

Spirometry

Answer 1

Measures the volume of air breathed in and out and generates a tracing

Question 2

Tracing

Answer 2

Used to calculate:

• Tidal volume
• Vital capacity
• Flow rate of air movement

Question 3

Pulmonary function test

Answer 3

Not diagnostic 
Patient assessment:
- changes
- response to therapy
- compensation 
- pre-surgical assessment 

Research:

• epidemiology
• study of growth and development
• investigation of disease processes

Question 4

FVC seated

Answer 4

Higher amount of air exhaled when standing but high intrathoracic pressure can reduce CO and cerebral blood flow so may faint

Always do spirometry when sitting down and use nose piece to stop air escaping from nasal cavity

Question 5

Spirometry results

Answer 5

Volume - time tracing
Volume - time graph
Flow - volume loop

Question 6

Collins waterseal spirometer

Answer 6

Inhale - Gas decreases and floating jar sinks and pen rises

Exhale- Gas passes into water jar rises and pen sinks

Question 7

Inspiration and expiration on a tracer

Answer 7

Inhalation - upwards deflection

Expiration - downwards deflection

Question 8

IRV

Answer 8

Difference between max inhaled air and normal inhaled air

Question 9

RV

Answer 9

Air that stays in lungs

Question 10

VC

Answer 10

IRV + TV + ERV
or
IC + ERV

Max inspiration and expiration

Question 11

FRC

Answer 11

ERV and RV

How much air left in lungs after a normal exhale

Question 12

Maximum filling factors

Answer 12

Determined by:

• Max inspiratory effort - muscle weakness due to deformity or injury
• Recoil force of lungs - if stiff

= restrictive deficit

Question 13

FVC

Answer 13

Forced expiratory max volume

• reduced in restrictive disorders

Question 14

FEV1

Answer 14

Volume of air exhaled in 1 second during forced expiration

• decreases with narrowing of airways and airway closure - obstructive deficits
  e. g. asthma and COPD

Question 15

PEF

Answer 15

Maximal speed of airflow when exhaling

Shown by slope of graph
Or measured by peak flow spirometer

Speed decreases in asthma

Question 16

Obstructive deficit spirometry

Answer 16

FVC - normal
FEV1 - reduced
FEV1/FVC - below 70%

Question 17

Restrictive deficit spirometry

Answer 17

FVC - reduced
FEV1 - reduced proportionately
FEV1/ FVC- greater than 70%

E.g Lung fibrosis

Question 18

Nomograms

Answer 18

FVC compared to value of people with same:

• age
• height
• gender

Question 19

How to get PEFR from volume time graph

Answer 19

Tangent at 0 with line

Question 20

How to tell the difference between COPD and asthma

Answer 20

Both show obstructive pattern

Give bronchodilator - asthma spirometry should improve but COPD does not

Question 21

Obstructive volume time graph

Answer 21

FVC not markedly reduced

FEV1 reduced

Question 22

Restrictive volume time graph

Answer 22

FVC reduced

FEV1 reduced proportionally

Question 23

Flow volume loop

Answer 23

peak - PEFR
TLC - flow at 0 L/sec

Obstructive:

• Scalloping
• Asthma - decreases PEFR

Restrictive:
- Narrowed vital capacity therefore tall and narrow