Topic 4 - Respiratory Dysfunction Flashcards
What is orthopnea?
SOB while laying down
What kind of breathing causes hypercapnia?
Hypoventilation
What kind of breathing causes hypocapnia?
Hyperventilation
Can there be inadequate oxygenation of tissues without apparent cyanosis?
Yes, during CO poisoning
What might cause clubbing of the fingers?
Diseases that interfere with oxygenation of tissues, often accompanied by increases density of capillaries in the area.
How can you tell if clubbing is occuring?
When two fingers are pressed nail to nail, there should be should be a gap between them (negative Schamroth’s sign)
What causes RDS of the Newborn?
Infants born before 28 weeks have not begun producing surfactant yet.
This causes alveolar collapse.
How is IRDS treated?
Positive Pressure Respirators and surfactant spray
What is surfactant?
A detergent like lipoprotein produced by alveolar type II cells that reduces water molecule’s’ affinity for each other and prevents alveolar collapse by decreasing surface tension.
What is the most important
stimulus to prevent atelectasis and RDS?
Normal ventilation - O2 is used in the synthesis of surfactant and hypoventilation can lead to atelectasis.
Surfactant’s main role is preventing alveolar collapse (atelectasis), but what is its other role?
To waterproof the lungs and prevent fluid from moving into alveoli from capillaries - prevents pneumonia
What are some underlying causes of ARDS?
- Reduced perfusion (cardiogenic shock, trauma, major burns)
- Increases capillary permeability (pneumonia, sepsis, drug reaction)
- Direct injury to capillary tissue (Aspiration of GI contents, near drowning, oxygen toxicity)
What is oxygen toxicity?
Nitrogen play an important role in not being absorbed by the blood and therefore remaining in alveoli to prevent collapse. Additionally, oxygen is toxic to surfactant -producing cells and supports a high level production of free radicals.
Breathing air that is too high in oxygen can cause atelectasis.
An injured lung goes through 3 phases, what are they?
- Exudative phase
–> Leakage of water, protein, Blood cells - Proliferative phase
–> Lung replaces damaged cells - Fibrotic Phase
–> Excessive collagen production leads to scare tissue
What is hyaline membrane disease?
Part of the exudative phase of ARDS - alveoli fill with proteins, fluids, macrophages and debris.
Gas exchange is decreased.
What are the four main symptoms of ARDS?
- Dyspnea
- Severe hypoxemia
- Decreased lung compliance
- Diffuse bilateral pulmonary infiltrates
(Anything other than air in sites of gas exchange)
How is RDS managed?
–> Maintain lung ventilation w gentle positive pressure
–> Antibiotics + (steroids –> but only later in phases of disease)
Why should steroids only be used in later phases of RDS?
Corticosteroids reduce activity of the immune system - might prevent it from fighting microorganisms
How long does it take someone to begin recovering from RDS? What is the prognosis for recovery?
Recovery begins after 2~ weeks, and aprox 32-45% survive
Those who do recover regain 75% of lung function after one year.
What is pleurisy?
Inflammation of pleura - can lead to too much or too little fluid, which can be painful.
Each lung has a separate pleural cavity, why is this advantageous?
If one lung is damaged, they will not both be affected.
What condition will cause immediate lung collapse?
Anything that equalizes intrapleural pressure, which should be ~4 mm Hg less than atmospheric and intrapulmonary pressure
What is pneumothorax?
Air in the intrapleural space
What is pleural effusion?
Accumulation of fluid in the pleural space
What are the two kinds of fluids involved in pleural effusion?
Transudative
–> Watery fluid, due to disorders that increase bp or capillary oncotic pressure
Exudative
–> Fluid that contains protein, due to inflammation, infection, malignancy. May contain microorganisms
What is the most common symptom of pleural effusion?
Dyspnea - an inability to ventilate the lungs leads to hypercapnia
Why is resistance not usually significant in affecting the pulmonary ventilation of a healthy individual?
Resistance is determined by the diameters of conducting tubes and airway diameter at the beginning is large are diffusion takes over at the terminal bronchioles.
What are some sources of airway resistance?
–> Mucus/other obstruction
–> Infectious material
–> Tumors
–> PSNS
–> Thickening of airway walls
–> Loss of elasticity
How does the PSNS affect airway resistance?
Causes strong constriction of bronchioles due to inhaled irritants and histamine.
–> Asthma attacks
How does the SNS affect airway resistance?
Dilates bronchioles
What kinds of things diminish lung compliance?
–> Fibrosis
–> Blocks in respiratory pathways
–> Increased surface tension in alveoli
–> Ossification of costal cartilage
What are obstructive pulmonary diseases?
Issues with expiration lead to air left in lungs - trapped air volume
Causes an increase in total lung capacity residual volume, and functional residual capacity.
e.g., bronchitis, asthma
What are restrictive pulmonary diseases?
Issues with inspiration leading to a decreased vital capacity, total lung capacity, functional residual capacity, and residual volume.
What is minute/total ventilation?
The total air in or out of the lungs in 1 minute
What is the forced vital capacity?
A deep breath in followed by a forced exhale
–> Low in people with restrictive diseases