Pathology of Respiratory Tract/Pulmonary Infection Flashcards
Healthy people are mainly infected by…
Viruses or aggressive organisms
What are the types of mico-organism pathogenicity/ different types of pathogens?
Primary
Faculative
Opportunistic
What does a patients capacity to resist infection rely on?
State of the hosts defence mechanisms
Age of patient
What effect will being immunocompromised have on a patient’s likelihood to have an infection?
It increases the patient’s susceptibility (particularly from opportunistic pathogens)
What are the most common URTIs?
Coryza -common cold Sore throat syndrome Acute Laryngotracheobronchitis (croup) Laryngitis Sinusitis Acute epigottitis
As a result of vaccination, what pathogen is increasingly responsible for acute epiglottitis?
Group A beta-haemolytic streptococci
What are the most common lower respiratory tract infections?
Bronchitis
Bronchiolitis
Pneumonia
What is the main respiratory tract defence mechanism?
The macrophage-mucociliary escalator system
What are some other defences the respiratory tract uses against infection?
General immune system - Humoral and cellular immunity
Respiratory tract secretions
Upper respiratory tract as a filter
What can failure in any of these systems lead to?
An increased risk of a respiratory tract infection
In normal conditions, is the lower respiratory tract sterile or non-sterile?
Sterile
What cells trap dirt allowing it to be removed from the lower respiratory tract?
Alveolar macrophages
What is the function of the cillated cells in the respiratory tract?
To carry a layer of mucous upwards on the mucociliary escalator from the lower respiratory tract to the larynx
What happens to the mucous layer with dirt or foreign particles once it is swept up via mucociliary escalatory into the larynx?
It’s swallowed or spat out
What infection is fatal to people in a flu epidemic due to disruption of the mucociliary escalator?
Secondary bacterial infection
What is a big danger of cellular bronchitis, especially in small children?
Inflammatory exudate produced during infection can close off the airway very rapidly
What 3 categories can you class pneumonia into?
Anatomical
Aetiological
Microbiological
Microbiological classification is useful because…
Allows you to confirm what organism is causing infection and can plan appropriate treatment
Under what headings can pneumonia be classed, aetiologically?
Community Acquired Pneumonia
Hospital Acquired (Nosocomial) Pneumonia
Pneumonia in the Immunocompromised
Atypical Pneumonia
Aspiration Pneumonia
Recurrent Pneumonia
What is the most common aetiological classification of pneumonia?
Community acquired pneumonia
What two aetiological classes of pneumonia are generally caused by aggressive organisms?
Community and Hospital acquired
What aetiological class of pneumonia is caused by abnormal organisms?
Atypical Pneumonia
If a patient has a pneumonia infection alongside another condition (e.g. cardiac failure), what can it lead to?
Accumulation of secretions making it difficult to clear the infection
What anatomical distributions/patterns of pneumonia are there?
Bronchopneumonia Segmental Pneumonia Lobar Pneumonia Hypostatic P Aspiration P Obstructive P Retention P Endogenous lipid P
What does bronchopneumonia display as?
Displays acute inflammation at a pathological level
Has spots of infection and formation of pus in the lungs
What is seen on a chest x-ray of a patient with bronchopneumonia that relates to the focal nature of consolidation?
Bilateral basal patchy opacification
What is consolidation
The replacement of air in the lungs by another substance
What is seen in lobar pneumonia?
Consolidation/infection of an entire lobe
ilateral basal patchy opacification
The aggresiveness
What are some complications of pneumonia?
Pleurisy, Pleural Effusion and Empyema Organisation Constrictive bronchiolitis Lung Abscess Bronchiectasis
Pneumonia is still a potentially fatal disease
What can organisation lead to?
Mass lesions
Cryptogenic organizing pneumonia/ COP (BOOP)
Constrictive bronchiolitis
Cause of organising pneumonia?
Bronchopneumonia turning into fibrosis
What does BOOP stand for?
Bronchioloitis Obliterans Organising Pneumonia
10% of patients presenting with a lung abscess will have what?
An underlying tumour
Lung abscess can result from the obstruction of what structure?
The bronchus
What 3 pathogens cause lung abscesses?
Staph aureus
Some pneumococci Klebsiella
What is Bronchiectasis?
A severe dilation of bronchi
What causes Bronchiectasis?
Severe Infective Episode
Recurrent Infections
Proximal Bronchial Obstruction
Lung Parenchymal Destruction
When is bronchiectasis most common?
Childhood
What are the symptoms of a chronic bronchiectasis infection?
Cough
Haemoptysis
Abundant, purulent, foul sputum
What are the main treatments for bronchiectasis?
Postural drainage Antibiotics
Surgery
What might cause local bronchial obstruction and lead to recurrent lung infection?
Tumours
Foreign Bodies
What local pulmonary damage is a common cause of recurrent lung infections?
Bronchiectasis
What generalised lung disease is a common cause of recurrent lung infection?
COPD
Cystic Fibrosis
In what kind of patients might non-respiratory disease cause recurrent lung infection?
Immunocompromised
What causes aspiration Pneumonia?
Vomit traveling down the trachea and into the lung
What section of the lung is most common affected by aspiration pneumonia?
Apical segment of the right lower lobe
What type of pneumonia might affect someone after excessive alcohol consumption?
Aspiration pneumonia
What can oesophageal diseases/leasions lead to?
Aspiration pneumonia
What is an opportunistic lung infection
An infection caused by organisms not normally capable of producing disease in patients with functioning lung defences
Opportunistic infections are most common in what patients?
Immuno-compromised
What two things can bulk flow in airways be?
Laminar or turbulent
What does the air flow in airways depend on?
The pressure difference
What does turbulent flow in the upper respiratory tract do to inhaled air?
Humidifies/warms it
Pulmonary gas exchange occurs at what barrier?
Blood-air barrier
Gas moves by diffusion beyond…
Terminal bronchiole
What is Type I respiratory failure?
Failure to maintain arterial partial pressure of oxygen above 8 kPa
PaCO2 is usally normal or low
What is Type II respiratory failure?
Failure to remove CO2, so PaCO2 is above 6.5kPa
PaO2 is usually low
Four abnormal states are associated with Hypoxaemia are….
Ventilation / Perfusion imbalance - V/Q
Diffusion impairment
Alveolar Hypoventilation
Shunt
What pulmonary vascular change occurs in hypoxia?
Pulmonary arteriolar vasoconstriction
Pulmonary arteriolar vasoconstriction occurs when…
When alveolar oxygen tension falls
Alveolar oxygen tension falling can be a…
Localised effect
Do all vessels constrict if there is arterial hypoxaemia?
Yes
Why do vessels constrict?
As a protective mechanism - so blood is not sent to alveoli short of oxygen
In Hypoxia, what changes will occur in the amount of blood going to the abnormal lung?
Blood going to abnormal lung will be reduced when compared to normal
Outside lung disease - when might hypoxia occur?
At high altitudes with minimal O2
Severe bronchopneumonia can cause what abnormal state associated with Hypoxaemia?
Shunt
Bronchitis and Bronchopneumonia can cause what abnormal state associated with Hypoxaemia?
Ventilation/Perfusion abnormality (mismatch)
What is hypoxaemia?
An abnormally low concentration of oxygen in the blood.
To what abnormal state would treating with 100% oxygen make no difference due to no ventilation?
Shunt
What is the most common cause of hypoxaemia encountered clinically?
Low Ventilation/Perfusion (V/Q) mismatch
Hypoxaemia due to low V/Q responds well to small increases in what?
FlO2
Shunt is…
Blood passing from the right to left side of the heart without contacting ventilated alveoli
What are the common causes of Hypoxaemia in COPD?
Ventilation/Perfusion abnormality
Alveolar hypoventilation Diffusion impairment
Shunt
When would a ventilation/perfusion mismatch occur?
Airway obstruction
When could alveolar hypo-ventilation occur?
With a reduced respiratory drive
When would diffusion impairment occur?
Loss of alveolar surface area
When does a shunt occur?
Only during acute exacerbation
What would the cause of hypoxaemia likely be in a patient with chronic COPD? Why?
Alveolar hypoventilation (as breaths per minute are decreased and CO2 retained)
What is alveolar hypo-ventilation?
An insufficient amount of air moved in and out of the lungs
What effect does hypoventilation have on PACO2, PaCO2, PAO2 and PaO2?
PACO2 - increases PaCO2 - increases PAO2 - decreases PaO2 - decreases
Fall in PaO2 due to hypoventilation can be corrected by raising what?
FIO2
What is FIO2
The fraction of inspired air which is O2
Why can chronic hypoxia lead to pulmonary hypertension?
Causes bone marrow to produce more red blood cells which makes blood more viscous and difficult to move through blood vessels and lungs
What is Chronic Cor Pulmonale?
Hypertrophy of the right ventricle resulting from disease affecting the function and/or structure of the lung
