Ventilation - L3 Flashcards
2 types of respiratory diseases?
Obstructive and restrictive
What is pulmonary minute ventilation?
It is the total volume of air entering and leaving
respiratory system each minute
What is minute ventilation formula?
= VT (Tidal Volume) x Respiratory Rate
What is normal respiration rate?
12 breaths per minute
What is normal VT?
500 mL
What is normal minute ventilation?
500 mL x 12 breaths/min = 6000 mL/min
Which is more important alveolar ventilation or pulmonary ventilation?
Alveolar ventilation is more important than pulmonary ventilation
What is alveolar ventilation?
It is the volume of air exchanged between the atmosphere and the alveoli per minute
What is less alveolar ventilation or pulmonary ventilation?
Alveolar ventilation is less than pulmonary ventilation due to anatomic dead space
Alveolar ventilation formula?
Alveolar ventilation = (tidal volume – dead space) x
respiratory rate = (500-150 mL/br) x 12 br/min =
4200ml/min
is resistance of airways smaller or bigger in smaller ones?
resistance is smallest in smallest airways
What is there to match airflow to blood flow?
There are local controls
Which area is greater - blood flow (perfusion) or airflow (ventilation)?
The area in which blood flow - perfusion is greater than airflow - ventilation
What happens in obstructive respiratory diseases (3) and give some examples of the diseases:
- Airway narrowing
- Increased airway resistance
- Reduced flow during expiration
Examples: emphysema, chronic bronchitis, asthma.
What happens in restrictive respiratory diseases (3) and give an example of the diseases:
- Reduced compliance
- Scar tissue formation
- Fibrosis
Example: pulmonary fibrosis
What are some other conditions? 4
Diseases impairing diffusion of O2 and CO2
Neuromuscular disorders
Inadequate perfusion
Ventilation-perfusion imbalances
What is FEV 1.0?
Forced expired volume in 1 second
FVC - what does it stand for?
Forced vital capacity
FEV 1.0 / FVC?
Disease index i.e. <80%
Local controls which increase CO2 in area of small airflow what happens?
Causes relaxation of local airway smooth muscle
This causes dilation of local airways
This decreases airway resistance
Thus increases airflow
Local controls which decrease O2 in area of small airflow what happens?
There is an increase in contraction of local pulmonary arteriolar smooth muscle
This causes constriction of local blood vessels
This increases vascular resistance
Thus decreasing blood flow
If the local controls act to balance by decreasing CO2 in the lung area what happens?
This increases contraction of local airway smooth muscle and constricts local airways which increases airway resistance and decreases airflow
If the local controls act to balance by increasing O2 in the lung area what happens?
By increasing oxygen, this relaxes the local pulmonary arteriolar smooth muscle which dilates local blood vessels and decreases vascular resistance which thus increases blood flow
Obstructive disorders - type 1 what happens to the airway?
Airway is hyper reactive and there is reversible airway narrowing
