Ventilation And Gas Exchange Flashcards
What is the minute ventilation?
The volume of gas entering and leaving the lungs over a minute
How do you calculate the minute ventilation?.
Tidal volume x breathing rate
What is the average tidal volume?
0.5 L
What is the alveolar ventilation?
The volume of gas leaving and entering the alveoli
How do you calculate the alveolar ventilation rate?
(Tidal volume - dead space) x breaths per minute
What is the dead space?
It is the region of the respiratory system which does not participate in gas exchange
What is the conducting zone?
The first 16 generations of bronchi, equivalent to the anatomical dead space as no gas exchange occurs here
What are non-perfused parenchyma?
Alveoli without a blood supply and therefore do not participate in gas exchange, equivalent to the alveolar dead space
How do you calculate physiological dead space?
anatomical + alveolar dead space
What is the tidal volume?
The volume of gas breathed in / out in a normal breath
What is the inspiratory reserve volume?
The maximum volume of gas which can be breathed in on top of the tidal volume
Tidal volume + inspiratory reserve volume =
inspiratory capacity
What is the expiratory reserve capacity?
The maximum volume of air which can be expired after the tidal volume expiration
Residual volume + expiratory reserve volume =
functional residual capacity
Inspiratory capacity + functional residual capacity =
Total lung capacity
What is the residual volume?
The volume of air which remains in the lungs even after a complete exhalation is completed
What is the vital capacity?
Inspiratory reserve volume + expiratory reserve volume + tidal volume
It is the total volume of air which can be expelled from the lungs at maximum expiratory effort
What is the definition of the vital capacity of the lungs.
The greatest volume of air which can be expelled from the lungs after taking the deepest possible breath
What is hyperventilation.
Excessive ventilation of the lungs atop of metabolic demands which results in reduced concentrations of carbon dioxide = alkalosis
What is the alveolar dead space?
The capacity of the airways which should be able to undertake gas exchange but cannot
What is anatomical dead space?
The capacity of the airways that is incapable of undertaking gas exchange
What is Bradypnoea?
Abnormally slow breathing
What is tachypneoa
Abnormal,y fast breathing
What factors affect lung volumes and capacities?
Body size, sex, disease, age and fitness (genetics)
How many generations are there in the respiratory zone?
7
How many generations are there in the lungs?
23
What can increase someone’s dead space?
Snorkeling
Anaesthetic circuit
What can decrease someone’s dead space?
Tracheostomy
Cricothyroidotomy
What direction does the chest wall have a tendency to spring in?
Outwards
What direction do the lungs have a tendency to recoil in?
Inwads
When are the forces of the chest wall and lungs in equilibrium?
At the end-tidal expiration which is the neutral position of the intact chest
What happens to the lung chest forces at functional residual capacity?
They are at equilibrium
Inspiratory muscle effort + chest recoil > lung recoil =
INSPIRATION
Expiratory muscle effort + chest recoil < lung recoil =
EXPIRATION
What are the lungs surrounded by?
A visceral pleural membrane
What is the inner surface of the chest covered with?
A parietal pleural membrane
What is the pleural cavity?
The gap between the two pleural membranes and contains protein rich pleural fluid
What does the intrapleural space do?
Makes the lung and chest wall work in partnership
What are the consequences of an intraplueral bleed?
Squashes the lung and makes it harder for the lung to expand and therefore ventilation is hindered
What are the consequences of a perforated chest wall?
A loss of the negative pressure in the intrapleural space, resting in a pneumothorax which reduces the effectiveness of ventilation
What is a haemothorax?
An accumulation of blood within the pleural cavity
What is a pneumothorax?
The presence of air or gas in the pleural cavity which causes collapse of the lungs
What type of breathing do we do on a day to day basis?
Negative pressure breathing
What is negative pressure breathing?
When the pressure inside the lungs is less than the pressure outside in the atmosphere, so the air is drawn in
What is positive pressure breathing?
When you increase pressure in the airways, above alveolar pressure - this can be achieved through performing CPR, or using a mask when in a fighter plane
What are some examples of positive pressure breathing?
CPR
mechanical ventilation - pushing air into lungs
Fighter pilots
What are the two classifications of inspiratory muscle forces?
A pulling force in one direction (like a syringe)
An upwards and outwards swinging force (like a bucket handle)
What type of inspiratory muscle force does the diaphragm use?
A unidirectional pulling force