Pressure Difference in Ventilation Flashcards
Ventilatory Process
- The pressure difference in the lungs
- The elastic properties of the lungs and chest wall.
- The dynamic characteristics of the lungs and how they affect ventilation.
The characteristics of normal and abnormal ventilatory patterns.
Difference between two pressure
Pressure Gradient
Pressure Gradient
- Moving air in and out of the lungs.
2. For maintaining the lungs in inflated state.
It is the pressure difference between two points in a tube or vessel. It is the force moving gas or fluid through the tube or vessel.
Driving pressure
The pressure difference s that occur across the airway wall, calculated by subtracting the intra-airway pressure from the pressure on the outside airway.
Transmural Pressure
Has a natural tendency to move outward or to expand, as a result of the bones of the thorax and surrounding muscle.
Chest walll
Have a natural tendency to move inward or collapse because of the natural elastic properties of the lung tissue
Lungs
Defined as the change in lung volume per unit pressure change.
Lung compliance
Determines how much air, in liters, the lung will accommodate for each centimeter of water pressure change.
CL
The normal lung compliance ____________ is actually the end result of the “combined” chest wall compliance and lung compliance.
0.1 L/H20
The normal lung compliance ____________ is actually the end result of the “combined” chest wall compliance and lung compliance.
0.1 L/H20
Natural ability of matter to respond directly to force and return to its original resting position or shape after the external force no longer exists.
Elastance
Shows that the distending pressure of a liquid sphere is
Laplace’s law
Laplace’s Law
- Directly proportional to the surface tension of the liquid.
- Inversely proportional to the radius of the sphere.
Refers to the study of forces in action.
Dynamic
The pressure changes required to move the gas
- Poiseuille’s law for flow and pressure.
2. Airway resistance equation.
Refers to a gas flow that is streamlined.
Laminar gas flow
Refers to gas molecules that move through a tube in a random manner.
Turbulent gas flow
Occurs in the areas where the airways branch.
Tracheobronchial gas flow
Type of glass flow
Laminar gas flow
Turbulent gas flow
Tracheobronchial gas flow
Product of airway resistance and lung compliance.
Time constant
Time constant is the time necessary to inflate a particular lung region to about _______ of its potential filling capacity.
63%
Defined as the change in the volume of the lungs divided by the change in the transpulmonary pressure during one breath.
Dynamic compliance
Determined during a period of no gas flow, whereas dynamic compliance is measured during a period of gas flow.
Lung compliance
Definded as the volume of air that normally move into and out of the lungs in one quiet breath.
Tidal volume
Tidal volume ideal body weight.
7 to 9 mL/kg
Normal adult ventilator rate is about 15 breaths per minute.
Ventilator rate
The IE ratio is usually about 1:2. That is, the time required to inhale a normal breath is about one half the time required to exhale the same breath.
Time relationship between inhalation and exhalation
Ventilatory Process consist of:
Tidal Volume
Ventilator rate
Time relation between inhalation and exhalation
Only the inspired air that reaches the alveoli is effective in terms of gas exchange.
Alveolar ventilation
Equal to the tidal volume minus the dead space ventilation multiplied by the breaths per minute.
Minute alveolar ventilation
The volume of inspired air that does not reach the alveoli and is not effective.
Dead space ventilation
The volume of gas in the conducting airways: the nose, mouth, pharynx, larynx and lower airways down to, but not including the respiratory bronchioles.
Anatomic dead space
The volume of anatomic dead space is approximately equal to
1 mL/lb of idea body weight
Occurs when alveolus is ventilated but not perfused with pulmonary blood.
Alveolar dead space
The sum of the anatomic dead space and alveolar dead space.
Physiologic dead space
The movement of gas molecules from an era relatively high concentration of gas to one of low concentration.
Diffusion
Describes the behaviour of gases surrounding the earth.
Ideal gas law
Temperature remains constant, pressure will vary inversely to volume.
Boyle’s law
Pressure remain constant, volume and temperature will vary directly.
Charle’s law
Volume remains constant, pressure and temperature will vary directly
Gay-Lussac’s law
States that in a mixture of a gases, the total pressure is equal to the sum of the partial pressures of each separate gas.
Dalton’s law
The force exerted by the atmospheric gas surrounding the earth, towards the surface of the earth.
Barometric Pressure
