The Respiratory System Measurement of Lung Function

Question 1

Measurement of Lung Function

Answer 1

Spirometry
Assessment of lung function
Volume
Flow
Lung Plethysmograph
MIR Spirolab
Wright Flow meter
Oximetry
c

Question 2

Respiratory volume

Answer 2

is the term used for various volumes of air moved by or associated with the lungs at a given point in the respiratory cycle. There are four major types of respiratory volumes: tidal, residual, inspiratory reserve, and expiratory reserve

Question 3

TLC

Answer 3

Total Lung Capacity

Question 4

FRC

Answer 4

Functional Residual Capacity

Question 5

ERV

Answer 5

Expiratory Reserve Volume

Question 6

IRV

Answer 6

Inspiratory Reserve Volume

Question 7

RV

Answer 7

Residual Volume

Question 8

FVC

Answer 8

Forced Vital Capacity

Question 9

IC

Answer 9

Inspiratory Capacity

Question 10

VT

Answer 10

Tidal Volume

Question 11

VC

Answer 11

Vital Capacity

Question 12

Tidal volume (TV)

Answer 12

is the amount of air that normally enters the lungs during quiet breathing, which is about 500 milliliters

Question 13

Expiratory reserve volume (ERV)

Answer 13

is the amount of air you can forcefully exhale past a normal tidal expiration, up to 1200 milliliters for men

Question 14

Inspiratory reserve volume (IRV)

Answer 14

is produced by a deep inhalation, past a tidal inspiration. This is the extra volume that can be brought into the lungs during a forced inspiration.

Question 15

Residual volume (RV)

Answer 15

is the air left in the lungs if you exhale as much air as possible. The residual volume makes breathing easier by preventing the alveoli from collapsing.

Question 16

Respiratory capacity

Answer 16

is the combination of two or more selected volumes, which further describes the amount of air in the lungs during a given time.

Question 17

Total lung capacity (TLC)

Answer 17

is the sum of all of the lung volumes (TV, ERV, IRV, and RV), which represents the total amount of air a person can hold in the lungs after a forceful inhalation. TLC is about 6000 mL air for men, and about 4200 mL for women.

Question 18

Vital capacity (VC)

Answer 18

is the amount of air a person can move into or out of his or her lungs, and is the sum of all of the volumes except residual volume (TV, ERV, and IRV), which is between 4000 and 5000 milliliters. Inspiratory capacity (IC) is the maximum amount of air that can be inhaled past a normal tidal expiration, is the sum of the tidal volume and inspiratory reserve volume. On the other hand, the functional residual capacity (FRC) is the amount of air that remains in the lung after a normal tidal expiration; it is the sum of expiratory reserve volume and residual volume.

Question 19

How Is Residual Volume Measured?

Answer 19

There is no way to measure residual volume directly, but it can be calculated indirectly with a pulmonary function test. Other lung volumes and capacities must first be measured directly, usually with spirometry, before RV can be calculated.

Helium Dilution Test
During a helium dilution test, you would breathe from a container containing a known fraction of helium gas. A spirometer measures the change in the concentration of the gases in the container. This test is conducted in a closed system circuit. It is used less frequently than body plethysmography.

Body Plethysmography
The body plethysmography test measures the total amount of air the lungs can hold. During this test, you would sit inside an airtight plethysmograph booth and breathe through a mouthpiece while pressure and airflow measurements are collected.
As you exhale, the volume of your thoracic cavity can be calculated by recording the change in pressure of the entire chamber.Body plethysmography is the most frequently used method for calculating FRC and residual volume and it yields the most accurate measurements—but it is also the most expensive

Nitrogen Washout
Another closed-circuit test, a nitrogen washout, can also be used to determine FRC, but this method is rarely used.

Question 20

Lung Plethysmography

Answer 20

Accurate determination of lung volumes
Expensive equipment
Not portable
May be combined with gas dilution methods
Boyle’s Law

Question 21

Clinical Significance Residual volume

Answer 21

can be used to help diagnose or measure the severity of obstructive lung diseases, such as chronic obstructive pulmonary disease (COPD), asthma, and bronchiectasis. These conditions are characterized by airway inflammation, collapsible airways, expiratory flow obstruction, and air trapping.

Question 22

obstructive lung disease

Answer 22

inflammation and decreased elastic recoil cause increased airway resistance and lead to premature small airway closure during expiration. As a result, excess air is trapped and left in the lung after you breathe, leading to an increase in residual volume.

Question 23

restrictive lung diseases

Answer 23

On the other hand, restrictive lung diseases such as pulmonary fibrosis and sarcoidosis, or extrinsic processes like kyphosis and obesity, restrict lung expansion. As a result, less air is retained in the lungs after maximal expiration and therefore less residual air than normal is left in the lungs after expiration. 

Question 24

Electronic spirometry- MIR Spirolab

Answer 24

Portable equipment
Expiratory Flow curve assessed
Patient performance compared with predicted values
-Height: a big person will have big lungs!
-Age: Lung capacity decline with age
-Sex: thoracic dimensions are different Male/Female
-Race
Changes monitored over time (months) or for effect of drugs
Several measurements taken to assure optimum performance
Best values used (it is not an average, it is the best value of 3 performance)

Question 25

Forced expiratory volume (FEV1).

Answer 25

This is the amount of air expired during the first seconds of the FVC test. - Litres

Question 26

Peak expiratory flow rate (PEFR).

Answer 26

This is the fastest rate that you can force air out of your lungs. L/min

Question 27

Forced vital capacity (FVC).

Answer 27

This is the amount of air exhaled forcefully and quickly after inhaling as much as you can. Liters

Question 28

restrictive disease examples

Answer 28

pulmonary fibrosis, infant respiratory disease syndrome, weak respiratory muscles, pneumothorax

Question 29

restrictive disease description

Answer 29

volumes are decreased- often in a normal range( 0.8-1.0)

Question 30

obstructive disease examples

Answer 30

asthma, COPD, emphysema

Question 31

obstructive disease description

Answer 31

volumes are essentially normal but flow rates are impeded
often low (asthma can reduce the ratio to 0.6 emphysema can reduce the ratio to 0.78-0.45
obstructive pattern is defined when FEV1/FVC is less than or equal to 70% in adults and less than 85% in children

Question 32

FEV1:

Answer 32

Forced Expiratory Volume in 1 second
PEFR, FEV1 and FVC are indicators of lung health

Question 33

Spirometry should not be performed when the individual presents with:

Answer 33

Hemoptysis of unknown origin
Pneumothorax
Unstable cardiovascular status (angina, recent myocardial infarction, etc.)
Thoracic, abdominal, or cerebral aneurysms
Cataracts or recent eye surgery
Recent thoracic or abdominal surgery
Nausea, vomiting, or acute illness
Recent or current viral infection
Undiagnosed hypertension

Question 34

Wright Flow Meter

Answer 34

Cheap
Simple
Single variable measured:
Peak Expiratory Flow Rate PEFR

Question 35

Pulse Oximetry

Answer 35

Oximeter add-on to spirometer or stand –alone device allows measurement of blood oxygen saturation and HR

Non-invasive
Measures O2 saturation of haemoglobin
effectiveness of ventilation
Assesses red and infrared spectrum light transmission through a tissue during pulse flow
Values closely correlated with arterial O2 saturation
Carbon monoxide or cyanide poisoning
detected as high O2 saturation
Does not detect anaemia (unless Hb levels known)
measures % saturation
Hb may still be fully saturated even if low
some systems able to monitor Hb levels also

Question 36

Breathing sounds

Answer 36

Auscultation
Using stethoscope to listen to internal sounds

Normal
Crackles
small airways & alveoli popping open
infection
Wheeze
asthma & COPD

Question 37

Auscultation

Answer 37

Using stethoscope to listen to internal sounds