Respiratory Flashcards
What is the method of respiration for inspiration?
Requires energy - ATP
Chest expands (intercostals contract, rib cage up and out)
Diaphragm flattens - increase in thoracic space, lungs expand)
Lungs are attached to chest wall via parietal pleura so as chest expands, pressure drops - neg pressure (creates vacuum)
Air rushes through naso and oropharynx to fill vacuum and lungs expand until pressure equalises
What is the mechanism of respiration for expiration?
Requires no energy
Elasticity of lung tissue (compliance) and lung muscles increase in resistance until pressure inside the lungs is equal to pressure outside
Diaphragm collapses - dome shape - decrease in thoracic volume and lungs compress
Lung vol begins too deeecrease and intrathoracic muscles relax causing chest volume to decrease and increase in air pressure in lung
Increase in pressure causes gas to be forced out of lung up through trachea and out of naso and oropharynx
CO2 and H20 Vapour are exhaled
What is tidal volume?
Amount of air breathed out
Usually 6mls per kg
Dependent on lung size
What is functional residual capacity? FRC
Amount of air present in lungs at the end of passive exhalation
Is a measurement of elasticity of the lung tissue
Loss of elasticity - increase in lung resistance and decrease in FRC
What is forced expiratory volume? FEV
Total amount of air exhaled in one breath over a period of time
Measured using spirometer - decrease in FEV may indicate loss of FRC - some lung damage
Conditions that affect lung flow?
Bronchiecstasis
PE
CF
Lung cancer
How to measure lung flow
Peak expiratory flow rate (PEFR)
Peak flow vol are calculated by height in children and by age,sex and height in adults
What conditions can bronchoconstriction?
Asthma, COPD, Bronchitis, Bronchiecstasis, Emphysema, pulmonary fibrosis, anaphylaxis can all cause narrowing of airways
What is pulmonary fibrosis?
Scarring of the alveoli due to repeated infection or exposure to hot gas
Alveoli loses elasticity and we’re unable to expand or contract - increases resistance within the lung and increase effort required to start a breath
Scarring also affects the tissue of the alveoli and means that gas exchange can not happen over this membrane (dead space)
What is emphysema?
Restrictive lung disease
Repeated infection cause significant changes to elasticity of alveoli increasing resistance
Alveoli can lose surface areas as they stretch nd collapse
What is surfactant?
A substance that is secreted by lung lamellar cells in order to reduce surface tension and reduce adhesion with alveolar tissue
Stop alveoli sticking together and collapsing at the end of exhalation and reduces WOB
What is atelectasis?
Adhesion of alveolar tissue
Can be caused by lack of surfactant or an increase in thick sticky mucous
Oxygen saturations
O2 bings with haemoglobin- oxyheamoglobin
Once discharged all O2 - deoxyheamoglobin
CO2 binds with empty haemoglobin cells and these transport to the lungs to be released
What is a pulse oximetry and how does it work?
Non-invasive
Determines O2 saturation of the capillary blood and the pulse rate
A clip with a sensor is attached to the fingertip
Sensor consists of 2 parts: light source emits red and infrared light which penetrates skin. The light receiver records light intensity and determines how much light of the different light colours was absorbed.
Usually precise with 4% deviation with arterially measured O2 sats.
Can detect oxyhemoglobin and reduced haemoglobin but not other haemoglobin variants like carboxyhaemoglobin or methemoglobin
What are normal O2 sats in an adult and in someone with COPD or pulmonary fibrosis?
95-100%
COPD/PF - 88-92%
