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
What is the forced expiratory volume?
The amount of air exhaled in the first second of a forced exhale.
–> Should be 80%
–> Low in those with obstructive diseases
What kinds of conditions might cause ischemic hypoxia?
–> Congestive heart failure
–> Embolism
–> Thrombosis
What is histotoxic hypoxia, and what might cuase it?
Hypoxia due to metabolic poisons.
–> Cyanide prevents cells from using oxygen
What is hypoxemic hypoxia, and what might cause it?
Reduced arterial PO2
–> Pulmonary diseases impairing ventilation
–>Breathing low O2 air
–> CO poisoning
Low PCO2 might cause____
Periods if apnea until increased PCO2 stimulates respiration
What are the two kinds of sleep apnea?
Obstructive
–> Relaxation of muscles that support soft throat tissue
Central
–> Defect in respiratory center in brainstem (more serious)
What are the two acute obstructive airway diseases?
–>Acute Bronchitis
–> Asthma
What is acute bronchitis?
Increased mucus production + bronchial swelling which leads to dysfunction of cilia due to viral or bacterial infection
What is asthma?
Episodic hyperresponsiveness and inflammatory response, can be extrinsic or intrinsically triggered.
What kinds of things can help someone with allergic asthma?
–> Allergy test to determine and avoid triggers
–> Allergy shots
Describe the process of triggering an asthma attack.
IgE-mast cell interaction leads to the release of histamine, prostaglandins, and leukotrienes which trigger:
–> Bronchospasm
–> Increased secretion by goblet cells
–> Mucosal swelling
Describe the two phases of an asthma attack.
Early Phase
–> 15-30 min
–> Mainly bronchospasm
Late Phase
–> Peaks in 2-6 hours
–> Airway edema & increased mucus production
Although the presence of an allergen is necessary to elicit a reaction in someone with asthma, there must also be another precipitating factor. List a few of them.
–> Stress
–> Exercise
–> Infection
–> Strong emotion
How many exposures to an allergen does it require to trigger an asthma attack?
Two exposures:
1st one activates T helpers and leads to IgE productions and recruitment of eosinophils
Subsequent exposures cause IgE on mast cells to trigger an inflammatory response.
How is an asthma attack treated?
Ventolin in congruence with a steroid puffer
What is intrinsic asthma? Who does it affect most often?
Asthma caused by anything other than allergies, such as smoke, viruses, hyperventilation, anxiety, cold air, etc.
Patient may test negative for personal and family history of allergies. Will not be seasonal or helped by allergy shots
Usually affects adults, disproportionately women.
How is COPD different than asthma?
In both COPD and asthma, expiratory airflow is obstructed and exacerbations and remission are common.
Unlike asthma, COPD causes an accumulation of pulmonary damage.
What is bronchiectasis?
Permanent dilation and distortion of bronchi and bronchioles due to the breakdown of airway smooth muscle and connection tissue, caused by chronic infection and inflammation.
What are the symptoms of bronchiectasis?
–> Chronic productive cough
–> Dyspnea
–> Fever
–> Weakness + weight loss
How can bronchiectasis be treated?
Preventing the frequency and limiting the severity of chronic bronchitis and asthma.
Immunizations and antibiotics protect against infection
How does CF affect the respiratory system?
Predisposes the individual to infection by creating thick mucus that obstructs airways and protects microbes.
What is the diagnostic criteria for CF?
- Increased sodium + chloride in sweat
- Deficient pancreatic enzymes in GI secretions
- Chronic pulmonary infections
- Family history
What are the symptoms of CF?
–> Pancreatic insufficiency
–> Tenacious mucus in airways
–> Infertility in men and reduced fertility in women
How does CF cause more viscous mucus?
Dysfunctional CFTR causes reduced chloride secretion by cells. Because CFTR has an inhibitory effect on sodium reabsorbing, ENAC (a sodium channel) remains open and builds within the cell.
As a result, ions build up in the cell and water remains in the cell as well and is unable to dilute mucus.
How are the respiratory issues associated with CF treated/managed?
Manage symptoms with:
–> Bronchodilators
–> mucolytic agents
–> Dornase alfa (ribonuclease) digests DNA by lysed cells and reduced mucus viscosity.
–> High dose antibiotics + immunizations up to date
What causes chronic bronchitis and who does it affect most?
Long term exposure to irritants
(90% are current or former smokers)
How is Chronic bronchitis treated?
Bronchodilators, immunizations, and quitting smoking
What is pulmonary emphysema? What causes it?
Permanent enlargement of alveoli and deterioration of alveolar walls due to repeated episodes of chronic bronchitis
What is genetic AAT?
2% of people have genetic anti alpha trypsin deficiency, which predisposes them to earlier onset pulmonary emphysema.
What is expiratory collapse and who does it affect most often?
What do those who experience it do to prevent it?
Collapse of alveoli while breathing out - occurs in emphysema.
Pursed lips breathing increases air pressure in lungs and prevents it.
What are the clinical manifestations of emphysema?
Often caught late due to the lungs’ ability to compensate.
–> Dyspnea upon exertion, and then at rest
–> Pursed lip expiration
–> decreased vital capacity
–> Barrel chest
–> Hypercapnia
–> Polycythemia
How is emphysema treated?
–> Cessation of smoking
–> Oxygen therapy
–> Pulmonary rehab
–> Surgery or transplants
–> AAT deficiency treated with enzyme replacement
Describe the process of a TB infection.
- Most people do not develop active TB infections. Primary infections are walled off in fibrous/calcified tubercles or granulomas.
- The bacteria might break out if immunity is low –> Which will lead to fever, night sweats, weight loss, racking cough + blood
How is a TB infection treated?
Bacterium grows very slowly, so a 12 month drug therapy is needed.
In those who stop taking their antibiotics, they risk the chance of developing a drug resistant strain
What are the clinical manifestations of TB?
–> Initially symptom free or mild bronchopneumonia
During an active infection there will be signs of chronic inflammation, advanced might cause necrosis. Chest pain and cough are also present.
How is TB prevented?
–> Education and screening
–> Antibiotics (Isoniazid + rfampin combo) for 1-3 years. Other antibiotics might be used for resistant strains.
What is pneumonia?
Inflammation of the respiratory unit tissues.
Insult causes acute inflammatory response, which leads to excess water and plasma proteins in the lower lung lobes.
This build up of fluid and hemorrhagic exudate in the alveolar space is a perfect medium for the proliferation of bacteria
What is the most common cause of bacterial pneumonia?
Streptococcus pneumoniae
What are some clinical manifestations of pneumonia?
–> Fever
–> Tachypnea
–> Productive cough with rusty coloured sputum
–> Pleuritic chest pain
What is the most consistent factor in hospital acquired pneumonia?
Tracheal intubation + excessive antibiotic treatment
How can pneumonia be prevented and treated?
–> Immunization of high risk patients
–> Post op care (turning, deep breathing, early ambulation)
–> Antibiotics therapy
–> Treat respiratory failure with drugs, O2, and mechanical ventilation as needed
Why is it important that post operative patients become active again as soon as possible?
Deep breathing and movement increase surfactant production
Which is more severe: Viral or bacterial pneumonia?
Bacterial for most people, however viral infections can be fatal in children
What is the major concern in someone with viral pneumonia?
That it will leave them susceptible to a secondary bacterial infection.
Which kind of viruses usually cause viral pneumonia?
–> Influenza
–> Adenovirus
–> VZV
What is croup?
Subglottic inflammation and edema which causes airway to narrow. Usually viral in origin.
Which two sounds are indicative of croup?
–> Stridor
–> Barking cough
Which virus causes croup most often?
Parainfluenza
How is croup treated?
–> Steam at home
If needed:
–> Corticosteroids
–> Nebulized epinephrine (should only be used to bridge the gap between corticosteroid onset)
Which virus caused muscle weakness and flaccid paralysis in young people in 2014?
Enterovirus D68
Club shaped spike proteins are indicative of which virus?
SARS
What are some risk factors for increased severity of a covid infection?
–> Age (Elderly + Infants)
–> Presence of coronary artery disease
–> Diabetes
–> Hypertension
–> Chronic respiratory conditons
COVID triggers a massive immune response, how does it do this?
By replicating in alveolar epithelial cells
–> Due to the loss of ability of these cells to promote vasodilation and fibrinolysis, COVID also results in a hypercoagulable state
