27. Work of Ventilation 1 Flashcards
What is work of breathing?
Work required to move the lung and chest wall
Higher tidal volume leads to an increase in what type of work?
Elastic
Higher rate leads in an increase in what type of work?
Non-elastic
What is elastic work?
Force to expand the lung against its elastic properties
What is resistive/non-elastic work?
Force to overome air-flow resistance
What is compliance?
Ease with which the lungs can be stretched or inflated
Compliance= Change in lung volume/ change in transmural pressure
When is static compliance measured?
No airflow
Airway resistance does not contribute
When is dynamic compliance measure?
During airflow
What does specific compliance measure?
Elastic properties
Lung volume is taken into account
Compliance/FRC
What happens to the hysteresis curve in obstructive diseases?
Area in loop widens
Increased work of breathing
What happens to the hysteresis curve in restrictive diseases?
Curve is pulled to the right
More negative pressure is needed to overcome lung stiffness
What causes increased compliance?
Loss of elastin fibres
Early emphysema
Ageing
What causes decreased compliance?
Chest wall issues eg. scoliosis
Pulmonary fibrosis
What is elastance?
Measure of recoil force
What contributes to elastic work?
Tissue elasticity
Surface tension
What is the function of surfactant?
Reduces surface tension
Stabilises alveoli of different sizes
Contributes to immunity in the lung
What would happen to small alveoli without surfactant?
They would empty in bigger alveoli and collapse due to their higher pressure
What is the treatment of newborn respiratory distress syndrome?
Corticosteroids to mother
Oxygen through continuous positive airway pressure
Survanta
How does alveoli interdependence contribute to stabilisation?
When an alveolus in a group of alveoli begins to collapse, the surrounding alveoli are stretched
Neighbouring alveoli recoil in response, pulling the collapsing alveolus back open
