FRC Flashcards
What is intrapleural pressure?
pressure between the chest wall and the lungs
What happens during inspiration?
The atmospheric pressure in the air is greater than the transpulmonary pressure so air rushes in
What happens during expiration?
Although the atmospheric pressure doesn’t change, it falls below the atmospheric pressure so air rushes out
Why is intraplulmonary pressure greater than intrapleural pressure?
to keep the lungs against the chest wall
Boyle’s law
pressure of gas is inversely proportional to the volume
Intrapulmonary pressure in inspiration
increased lung volume so decreased intrapulmonary pressure so air comes rushing in
Intrapulmonary pressure in expiration
decreased lung volume so increased intrapulmonary pressure so air moves out of the lungs
What is transmural pressure made up of?
transpulmonary pressure and transthoracic pressure
What does a huff do?
makes intraplueral pressure positive which causes it to expand. sing abdominal muscles which will push on intrapleural space. This will cause dynamic compression.
What is FRC
balance between transpulmonary pressure and transthoracic pressure
normal breath huff
- This pressure reduces due to overcoming resistance in the airways as it goes up airways
- When pressure is equal to intrapleural pressure you get dynamic compression. This take less time. When you can’t feel them
- more peripheral airways
big breath up
equal pressure point will take longer for pressure to reduce. Lung volumes closer to the mouth. Takes longer to overcome the pressure which is why it takes longer.
When does FRC increase?
lung hyperinflation
air trapping, such as emphysema
during PEEP as it maintains the positive pressure
When does FRC decrease?
restrictive disorders
What are obstructive disorders?
Obstruction can occur when inflammation and swelling cause the airways to become narrowed or blocked, making it difficult to expel air from the lungs. This results in an abnormally high volume of air being left in the lungs (increased residual volume). Increased residual volume, in turn, leads to both the trapping of air and hyperinflation of the lungs—changes that contribute to a worsening of respiratory symptoms.
What are restrictive disorders?
Restrictive lung diseases are characterized by a reduced total lung capacity, or the sum of the residual volume mentioned above combined with the forced vital capacity (the amount of air that can be exhaled forcefully after taking a deep breath).
This occurs because of difficulty filling the lungs completely in the first place, and can be due to intrinsic factors (e.g. stiff lungs); extrinsic factors, such as when pressure from an enlarged abdomen limits the expansion of the lungs; or neurological factors, such as muscular dystrophy, where damage to the nervous system interferes with movements necessary to draw air into the lungs.
Obstructive lung diseases
chronic obstructive pulmonary disease (COPD) Chronic bronchitis Asthma Bronchiectasis Bronchiolitis Cystic fibrosis
Restrictive lung disease
Scoliosis Obesity Obesity hypoventilation syndrome Pleural effusion Malignant tumors Ascites (abdominal swelling caused by cirrhosis or liver cancer) Pleurisy Rib fractures
Paralysis of the diaphragm
Guillain-Barré syndrome
Myasthenia gravis
Muscular dystrophy
