Types of Ventilation and Lung Mechanics Flashcards
(20 cards)
What is eupnoea?
Eupnoea refers to normal or unlaboured breathing
- inspiration is active and involves the diaphragm and external intercostals
- expiration is passive during eupnoea
What is diaphragmatic breathing?
(deep breathing) type of breathing where the diaphragm is the primary muscle used for breathing.
- during low levels of activity, diaphragmatic breathing is sufficient
What is costal breathing?
(shallow breathing) type of breathing where the primary muscles used for breathing are the external intercostal muscles.
- can occur in situations such as pregnancy or obesity, when the diaphragm is restricted
What is hypoventilation?
Hypoventilation is a condition where there is inadequate alveolar ventilation, leading to an increase in VCO2/VA above normal
What are the possible causes of hypoventilation?
- a respiratory disease
- a behavioural response
- a reduced output of the respiratory controller in the brainstem.
- examples include COPD, behavioural response to pain, and alcohol overdose
What is the consequence of hypoventilation?
Can lead to respiratory acidosis, as poor CO2 excretion results in an increase in PACO2, PaCO2, H+, and a decrease in pH.
What is hyperventilation?
Condition where VCO2/VA decreases below normal, leading to excess alveolar ventilation
What causes hyperventilation?
- behavioral response
- or when the respiratory controller is stimulated by factors other than CO2, such as anxiety, panic or hyperventilation syndrome, and altitude
What is the consequence of hyperventilation on blood pH?
Leads to respiratory alkalosis, due to increased alveolar excretion of CO2, which causes a decrease in PACO2, then in PaCO2, and an increase in pH through H+ ions.
What is hyperpnoea of moderate exercise?
Refers to the increase in breathing rate and depth during moderate exercise, where the amount of CO2 produced by the body is precisely matched by the amount of CO2 exhaled, and the respiratory rate tracks CO2 production.
What stimulates hyperventilation during heavy exercise?
During heavy exercise above the anaerobic threshold, hyperventilation is stimulated by lactic acid, which activates the respiratory controller in the brainstem.
What is apnoea?
Apnoea refers to the cessation of breathing.
What are some causes of apnoea?
- voluntary breath-holding
- asphyxiation
- drug overdose
- obstructive sleep apnoea (OSA)
What is obstructive sleep apnoea?
Obstructive sleep apnoea (OSA) is a type of apnoea in which there is no airflow, but there are efforts to breathe and arousal.
What is compliance in lung mechanics?
The distensibility of an elastic structure and how easy it is to inflate the lungs
- change in volume for a given change in pressure
What is the relationship between volume and compliance in the lungs?
(inverse relationship)
Compliance of lungs decreases with increasing volume
- meaning that at higher volumes, more pressure is needed to increase the volume
What is elastance in lung mechanics?
- reciprocal of compliance
-a measure of the resistance to expansion
How is elastance related to pressure and volume in the lungs?
Elastance is the change in pressure needed for a given change in volume
What is Static Pressure-Volume Curve (Passive)?
Curve generated by measuring the lung volume at different airway pressures without any airflow (i.e., no respiratory muscle activity)
- low lung volumes = steep curve, indicating high compliance
- high lung volumes = curve levels off, indicating reduced compliance
- reflects the elastic properties of the lung and chest wall
What is Maximum Inspiratory and Expiratory Pressures (Static)?
Measure of the strength of the respiratory muscles
- Maximal inspiratory pressure (MIP): the maximum negative pressure that can be generated during a forced inspiration
- Maximal expiratory pressure (MEP): the maximum positive pressure that can be generated during a forced expiration
- Used as an index of respiratory muscle strength and to assess the presence of respiratory muscle weakness.
