Ventilation Flashcards
What is orthopnoea?
Positional difficulty in breathing
What is trachypnoea?
Abnormally fast breathing rate
What is bradypnoea?
Abnormally slow breathing rate
What is dyspnoea?
Difficulty in breathing
What is apnoea?
No breathing
What is hypopnoea?
Decreased breathing depth
What is hyperpnoea?
Increased breathing depth
What is physiological dead space?
Sum of alveolar and anatomical dead space
What is alveolar dead space?
Capacity of the airways that should be able to undertake gas exchange but cannot e.g. alveoli without blood supply
What is anatomical dead space?
Capacity of the airways incapable of undertaking gas exchange
What is alveolar ventilation?
Volume of air reaching respiration zone
What is respiratory rate?
Frequency of breathing per min
What is minute ventilation?
Volume of air expired in one minute
What are the two main components of the chest wall?
Lungs
Bone, muscle, fibrous tissue
What is the natural recoil of the rib cage and the lungs?
The ribs naturally recoil outwards
The lungs recoil inwards
The chest wall combines these so lung is larger than natural
What is the functional residual capacity?
At the end of tidal expiration where the rib cage and lungs are at equilibrium
What does the pleural cavity contain, and is its volume fixed?
Protein rich fluid
Yes
How does negative pleural pressure allow inspiration?
Negative pressure allows the lungs to expand as the chest wall expands
Why does a puncture in the lung/chest wall cause lung collapse?
Air/blood (haemo/pneumothorax) fills the pleural space, changing the fixed volume and elastic recoil means lung will collpase
What is tidal volume?
The volume of air inspired and expired during regular breathing
What is tidal breathing?
Amount of inspiration and expiration to meet metabolic demands
What marks the FRC?
End of a tidal breath
What is residual volume?
As the alveoli donβt fully empty (to prevent them from sticking together), the air remaining is residual volume
What is inspiratory reserve volume?
The volume of air that can be inspired after a tidal inspiration
What is expiratory reserve volume?
The volume of air that can be expired after a tidal expiration
What is total lung capacity?
It is TV, IRV, ERV and RV combined. Inspire max and fill lungs as much as possible
What is vital capacity?
TLC - RV or TV+IRV+ERV
How much we are able to inspire to expire at max
What is functional residual capacity?
ERV+RV
Air that is in the lungs during equilibrium
What is inspiratory capacity?
TV+IRV
How much extra air can be inhaled in addition to FRC
What are the units for measuring lung volumes?
cmH20
What is transmural and transpulmonary pressure?
transmural - pressure across tissue(s) e.g.transpulmonary, transthoracic and transrespiratory
transpulmonary - difference between alveolar and intrapleural
What is transrespiratory system pressure?
pressure difference drawing air in or out
lung and atmosphere
What is the standard against which pressure is measured?
Atmospheric pressure
Give examples of positive and negative pressure breathing
Breathing normally in negative
Ventilator uses positive
What is dead space?
Part of the airway and lung that isnβt involved in exchange
What is the alveolar dead space in healthy people?
0 - so physiological dead space equals anatomical dead space
What is the normal physiological dead space?
150ml
What is the conducting zone?
No gas exchange happens (anatomical dead space). Includes trachea, bronchi, pharynx etc.
What is the respiratory zone?
Part involved involved in exchange - alveoli mainly (air reaching here is equal to alveolar ventilation)
How can dead space be increased?
With ventilation - tubes become dead space
How can dead space be decreased?
Tracheostomy - removing some of the airway
How is a volume-time curve plotted?
Patients wear nose clip, inhale and then in mouthpiece expire as fast and hard as possible until RV reached (6 seconds)
What would a volume-time curve for a healthy person look like?
Initially the slope is very steep but then it is hard to get rid of the remaining air
What is the FEV1?
Volume of air expelled from the lungs in a second
What is FVC?
The forced vital capacity - how much can be expired after a deep breath
In a healthy person, what % of air is expelled in 1 second?
75
What is FET?
Forced expiratory time - amount of time required to expel all of the air from the lungs
How does obstructive lung disease affect FEV1, FET and FVC?
FEV1 and FVC lower and FET is higher
What is a normal FEV1/FVC ratio compared to restrictive and obstructive?
normal - 73
restrictive - 87
obstructive - 53
What factors affect lung volumes and capacities?
- body size: height and shape
- sex
- disease: pulmonary or neurological
- age: chronological or physical
- fitness: innate and training
At the end tidal expiration (FRC), what are the forces of the lungs and chest wall relative to eachother?
In equilibrium - this is the resting position
At rest, what is normal Palv, Patm and Ppl?
Patm: 0
Palv: 0
Ppl: -5 cmH20
At the end of inspiration, what must happen to Palv?
must return to 0 or breathing would continue
Give an analogy of the movement of the diaphragm and respiratory muscles
diaphragm - syringe (pulls in one direction)
respiratory muscles - like bucket handle (swings upwards and outwards)
On volume -time curves, what things can be looked for?
- FVC: full to as empty as possible
- FEV1: tells you about airways thickness e.g. constricted means less air comes out
- FET: expiratory time
What happens during emphysema?
surface area is lost
How is peak expiratory flow measured?
nose clip, inhales, exhale as hard and fast as possible. Exhalation doesnβt have to reach RV. Can compare to normal values
Flow volume loops - most modern as everything incorporated into one
nose clip, complete one tidal breath (A+B), inhale to TLC (C), exhale as hard and fast as possible (D), continue exhaling till RV reached (E). Then inhale to TLC (F).
What does the y axis and x axis mean on a flow volume loop?
Y AXIS - FLOW RATE
Anything going down is negative flow rate -
inspiration. Anything going up is expiration.
X AXIS - VOLUME
What does the flow volume loop look like in a person with mild obstructive lung disease?
Peak is lower, coving (indentation in expiratory curve towards end), displaced to the left
What does the flow volume loop look like in a person with severe obstructive lung disease?
lower peak, displaced to left and coving is worse (compared to mild obstructive)
What does the flow volume loop look like in a person with restrictive lung disease?
displaced to right and smaller loop
How does an extrathoracic obstruction affect the flow volume loop and why?
causes a flattening of the inspiratory curve - affects ability to breathe in
What happens to an extrathoracic obstruction when breathing in and out?
inspiration - sucked in
expiration - pushed away
What happens to an intrathoracic obstruction when breathing in and out?
inspiration - pushed away
expiration - sucked in
How does an intrathoracic obstruction affect the flow volume loop and why?
flattening of the expiratory curve - affects ability to breathe out
How does a fixed airway obstruction affect the flow volume loop and why?
blunted inspiratory and expiratory curve
During inspiration how must the equilibrium between the chest and lung be distorted?
inspiratory muscle effort and chest recoil> lung recoil
During expiration how must the equilibrium between the chest and lung be distorted?
expiratory muscle effort and lung recoil> chest recoil
Between the pleura what kind of pressure exists and what causes it?
There is small negative pressure caused by lung inward recoil and chest outward recoil
What is parenchyma in the lung tissue?
functional units - alveoli and the respiratory bronchioles (have some alveoli along their walls)
What are the two main things the lungs consist of?
Airways and parenchyma
How does restrictive lung disease affect FVC, FET and FEV1?
It limits the expansion of the thorax so FVC, FEV1 is low and FET is low (have less air in so can move it faster)
Give examples of obstructive lung disease
Chronic obstructive pulmonary disease (COPD - inc chronic bronchitis and emphysema)
Asthma
Bronchiectasis
Cystic Fibrosis
Give examples of restrictive lung diseases
Interstitial lung disease Sarcoidosis Pulmonary fibrosis Asbestosis Silicosis