Ventilation / Compliance Flashcards by Eilidh Seaton

What is the tidal volume

Volume of air that we breath in and out
Increased in pregnancy
500ml

How well did you know this?

Not at all

Perfectly

What is the inspiratory reserve volume

Max volume of air which can be drawn in above tidal volume
3000ml
Relies on lung compliance (elastic recoil) and muscle strength

How well did you know this?

Not at all

Perfectly

What is the expiratory reserve volume

Max volume of air which can be expelled below tidal volume

1100ml

How well did you know this?

Not at all

Perfectly

What is the residual volume

The. volume of gas in the lung at the end of a max expiration
1200ml
Stops alveoli collapsing

How well did you know this?

Not at all

Perfectly

What volume cannot be measured with spirometry

Residual volume

All other volumes can

How well did you know this?

Not at all

Perfectly

What are capacities

Lung volumes which do not change with breathing

How well did you know this?

Not at all

Perfectly

What is the vital capacity

Max volume of air that can be moved into and out of the lung
ESV + TV + IRV
4.5l
Changes in disease - as relies on compliance / resistance

How well did you know this?

Not at all

Perfectly

What is the functional residual capacity

The amount of air in the lung after normal expiration
ESV + RV
3L

How well did you know this?

Not at all

Perfectly

What is inspiratory capacity

The amount of air in the lung that can be breathed in
TV. + IRV
3L

How well did you know this?

Not at all

Perfectly

What is the total lung capacity

The amount of air in the lung after max inspiration

How well did you know this?

Not at all

Perfectly

What measures total lung capacity

Helium dilation
Hyperinflated =120%
Resitricted = 80%

How well did you know this?

Not at all

Perfectly

What is anatomical dead space

Air that never reaches the alveoli
150ml
Nitrogen washout measures

How well did you know this?

Not at all

Perfectly

What are visual ways of presenting lung volumes

Flow volume loop
Nitrogen washout graph
Vitalograph

How well did you know this?

Not at all

Perfectly

What is pulmonary ventilation

Total air in and out
INSIGNIFICANT
RR + TV

How well did you know this?

Not at all

Perfectly

What is alveolar ventilation

Fresh air getting to alveoli for exchange 
RR x (TV-anatomical dead space) 
Only 350ml of fresh air reaches alveoli when you inspire

How well did you know this?

Not at all

Perfectly

Where is alveolar ventilation gretest

Base of the lung
More compliant + stretch more when compressed / contracted
Small change in intrapleural pressure = large change in volume

What is the partial pressure

The pressure of a single gas in a mixture

Equivalent to % of gas x P of whole mixture

What is alveolar partial pressure of O2 and CO2

PO2 = 100mmHg (13.3)
PCO2 = 40mmHg (5.3)

What does hyperventilation cause

Increased alveolar as increased tidal volume
PO2 = 120
PCO2 = 20 - which is why a normal CO2 is bad if resp distress

What does hypoventilation cause

Decreased alveolar ventilation
P02 = 30
PCO2 = 100

What is the Law of LaPlace

P (transpulmonary) = 2x Surface tension / radius

What does law of Laplace mean

If alveolar radius decrease s or tension gets larger than P increases and alveoli collapse
The lungs tendency to recoil has to be overcome during inspiration
Harder to fill lungs with air than saline as increased tension to overcome

What does surfactant do

Reduces surface tension on alveoli so stop collapse

Also increase lung compliance and decrease tendency to recoil

How is surface tension greater

Air water interface on wall of alveoli

What is compliance

The change in volume of lung relative to change in pressure STRETCH over elasticity A higher lung volume = lungs stretched more so greater intrapleural pressure

What does it mean if lung is high compliance

Large increase in volume for small decrease in intrapleural pressure (more air in)

What occurs in disease

Emphysema = loss of elasticity so expiration needs effort Fibrosis = increased inspiration as decreased compliance so lungs need to work

What is obstructive lung disease

Air flow is obstructed and increased airway resistance More on expiration as compression exaggerates COPD / asthma

What is restrictive lung disease

Loss of lung compliance which restrict expansion of lungs and volumes Fibrosis / pneumothorax / pleural disease

What is spirometry

Used to measure lung volume FEV1 - FEV in 1s (4l) / FVC Should be 80%

What happens in obstruction

Air exhaled slower so total volume of air is reduced FEV decreased more than FVC Ratio reduced

What happens in restrictive

Rate of air flow reduced Total volume reduced due to limitations in expansion Ratio often constant or increased as large volume can be exhaled in 1s Not good to use if unwell as doesn't show change