Respiratory System 2 - Ventilation Flashcards
Define minute ventillation
The volume of air experied in one minute (or per minute)
Define respiratory rate
The frequency of breathing per minute
Define alveolar ventilation
The volume of air reaching the respiratory zone per minute
Define anatomical dead space
The capacity of the airways incapable of undertaking gas exchange
Define alveolar dead space dead space
The capacity of the airways that should be able to undertake gas exchange but cannot
Define physiological dead space
The sum of alveolar and anatomical dead space
Define hypoventilation
Inefficient ventilation of the lungs unable to meet metabolic demand
Define hyperventilation
Excessive ventilation of the lungs above metabolic demand
Define hyperpnoea
Increased depth of breathing to meet metabolic demand
Define hypopnoea
Decreased depth of breathing inadequate to meet metabolic demand
Define apnoea
Cessation of breathing
Define dyspnoea
Difficulty breathing
Define bradypnoea
Abnormally slow breathing rate
Define tachypnoea
Abnormally fast breathing rate
Define orthopnoea
Positional difficulty in breathing when lying down
Draw a lung volume time trace
- Tidal volume
- Inspiratory reserve volume
- Expiratory reserve volume
- Residual volume
- Functional residual capacity
- Inspiratory capacity
- Vital capacity
- Total lung capcity
Define capacity
The sum of two or more volmes
What is the inspiratory reserve volume?
The volume of air above tidal volume that would be in the lungs if you forced inhalation rather
What is the tidal volume?
The volume of air exhaled or inhaled in one breath at rest
What is the expiratory reserve volume?
The volume of air below tidal volume that would leave the lung following forced exhalation
What is residual volume?
The volume of air left in the lungs following forced exhalation
What is the functional residual capacity?
The volume of air left in the lungs following tidal exhalation
(Expiratory reserve volume + residual volume)
What is insipratory capacity?
The air that enters the lungs following forced inhalation
What is vital capacity?
The difference between the volume in the lungs following forced exhalation and the volume following forced inhalation
What is total lung capacity?
The volume of air in the lungs following forced inhalation
What affects lung volumes and capacities?
- Body size
- Fitness (primarily innate)
- Age
- Sex
- Disease
What is the respiratory zone?
- The area of the bronchioles that enter the lung tissue and exchange gas
- 16 generations
What is the conducting zone?
- The area of the trachea and bronchi where no gas exchange takes place
- 16 generations
- 150mL in adults
- Equivalent to anatomical dead space
Why is increased dead space bad?
It is a lot harder to get a good oxygen supply
Describe how the pressure and volume change in tidal breathing
- Initially there is a decrease in pressure, causing the volume to increase
- Air enters so the volume increases more, while the pressure increases to normal
- The pressure then increases, causing the volume to decrease as air moves out
- Once air has moved, volume decreases so the pressure decreases to baseline
At neutral position, following tidal expiration, what is the chest wall relationship?
The chest recoil (outwards) equals the lung recoil (inwards)
How does inspiration occur in the chest wall relationship?
Inspiratory muscle effort increases chest recoil (outwards) causing it to surpass lung recoil so the volume increases
How does expiration occur in the chest wall relationship?
Increased expiratory muscle effort causes lung recoil to surpass chest recoil, so the volume decreases.
How can the pleural membranes affect breathing pathologically?
- Intrapleural bleeding disrupts the chest lung relationship (haemothorax)
- Perforated chest wall causes air to enter making the lung collapse (pneumotorax
- Both of these disrupt the tight seal of the pleura
What is negative pressure breathing?
- At rest, to breathe in and out, the air moves due to changes in pressure
- The pressure gradient is generated by changing the lung pressure in relation to air, as opposed to at the mouth being pushed up or down the trachea
- This is like sucking a straw
When does positive pressure breathing occur?
- When the atmospheric pressure is above the alveolar pressure.
- Caused by mechanical ventilation, and mouth to mouth
Describe the three compartment model of the lung
- Three pressures - alveolar, pleural, and atmospheric
- The pressure that causes us to breathe is the transmural pressure (pressure inside - pressure outside the lungs)
How do volume time curves change in patients with a restrictive disease?
- If there is a restrictive disease, the patient cant fill their lungs with as much air or for as long as a normal patient
- Like a bear hug
How do volume time curves change in patients with a obstructve disease?
- If there is an obstructive disease, the patient will take a long time to reach the peak, and will breath in significantly less air
- Like something covering your mouth
Describe the procedure of volume time curve
- Patient wears a noseclip
- Patient inhales to total lung capcity
- Wrap lip around the mouthpiece then exhale as hard and fast as possible until residual volume is reached or 6 seconds pass
Describe the procedure of a peak flow test
- Patient wears noseclip
- Patient inhales to total lung capacity
- Patient wraps lips round mouthpiece
- Patient exhales as hard and fast as possible
- Exhalation does not have to reach RV
- Repeat at least twice and take highest measurement
Describe the procedure used to make a flow-volume loop.
- Patient wears noseclip
- Patient wraps lips round mouthpiece
- Patient completes at least one tidal breath (A&B)
- Patient inhales steadily to total lung capacity (C)
- Patient exhales as hard and fast as possible (D)
- Exhalation continues until RV is reached (E)
- Patient immediately inhales to TLC (F)
What happens to the flow volume loop if there is an obstructive disease?
- In a mild obstructve disease, there is displacement to the left and an indented curve (coving)
- In a severe obstructive disease there is a shorter curve, displaced to the left with a larger indentation
What happens to the flow volume loop is there us a restrictive disease?
- Displaced to the right
- Narrower curve
What happens to the flow volume loop in the three types if obstruction?
- Variable extrathoracic obstruction causes a blunted inspiratory curve
- Variable intrathoracic obstruction causes a blunted expiratory curve
- Fixed airway obstruction causes a blunted expiratory and inspiratory curve
Define pulmonary ventilation
- The total volume of air inhaled in one breath
- Equal to the alveolar ventilation + dead space ventilation
