LRTI Flashcards
What is present throughout the lower respiratory tract?
Mucus, cilia, immune cells and commensal organisms are present throughout the LRT.
Where can LRTI occur?
LRTI can occur at every level of the respiratory tract
what is tracheitis?
Tracheitis = rare, viral or bacterial infection of the trachea, often overlaps with laryngitis.
Often affects young children, if not treated quickly it can lead to life threatening complications.
What is bronchitis?
Bronchitis = LRTI affecting the bronchi, may be acute or chronic
what is bronchiolitis?
Bronchiolitis = infection of the bronchioles, usually in children under 2 yrs, viral, usually RSV
What is pneumonia?
Pneumonia = LRTI affecting the alveoli, may be lobar or multifocal
How common and what is a lung abscess?
How can they develop?
Lung abscess = liquefactive necrosis of lung tissue and formation of cavities containing necrotic debris/ fluid often caused by aspiration.
They are rare, lung abscess can be bronchogenic ( from aspiration, inhalation and airway damage) and haematogenic-dissemination from other infected sites.
What can a pleural infection lead to?
pleural infection = pleural effusion (build up of fluid between the two pleural layers around the lung) –> infection –> empyema (pus filled pocket within the pleural space).
which type of pathogen is the most likely to cause a pleural effusion?
What is pleural effusion secondary to pneumonia called?
Describe the three stages from infection within the lungs to empyema development.
Bacteria are the pathogens responsible for the majority of pleural effusion from infectious causes.
Pleural effusion secondary to pneumonia is termed paraneumonic effusion
First stage in exudative phase pleural fluid accumulates from increased pulmonary interstitial fluid traversing visceral pleura and due to increased permeability of the pleural capillaries from inflammation
If infection within the lung continues, bacteria may be able to pass through the visceral pleura into the plerual cavity and infect this space. This is called the fibropurulent stage.
Empyema is the third stage of pleural effusion spectrum, is defined as frank pus in the pleural cavity.
How can LRTI be classified?
Classified either by 1) location of infection 2) by cause
What are some of the causes of LRTI?
(think causative classifications)
- Infective exacerbation of COPD (chronic bronchitis and emphysema)
- Community acquired pneumonia (CAP) = usualyl due to organisms that are common and sensitive to first line antibiotics
- Hospital acquired pneumonia (HAP) = possibly due to organisms that are rare and resistnt to first line antibiotics
- Atypical pneumonia = due to uncommon organisms (e.g. pertussis)
- Secondary pneumonia = bacterial pneumonia following virtal LRTI
- Aspiration pneumonia = due to aspirating drinks, secretions etc..
- Opportunistic LRTI = due to immunodeficiency or immunosuppression
What agent is most likely to cause acute bronchitis?
What agent is most likely to cause chronic bronchitis?
What are typical microbes that cause bronchitis?
Acute bronchitis mostly viral causes
Chronic bronchitis mostly bacterial
Typical microbes:
Viral –> Rhinovirus and influenza
Bacterial –> Streptococcus pneumoniae
Haemophilis influenzae
Other causes –> possibly underlying airway damage
What microbes are involved in pneumonia (typically)?
Whats a possible underlying cause?
Microbes –> influenza virus
Streptococcus pneumoniae
Staphylococcus aureus
Possibly underlying immunocompromised
What does tuberculosis cause?
What are the different classifications of the disease it can cause?
Tuberculosis causes bronchopneumonia w/ w/out haemoptysis
Note: bronchopneumonia = foci of consolidation (pus in alveoli and adjacent air passages) scatted in one or more lobes of one or both of the lungs.
Lobar pneumonia = actue inflammatin in one lobe of the lung
interstitial pneumonia = pneumonia within tissue inbetween the alevoli, also called interstitial pneumonitis.
What are the specific risk factors for LRTI?
- Extremes of age –> younger children and older adults
- Stress and starvation
- Immunocompromised host –> LRTI more common w HIV
- Compromised barries to infection:
- smoking increases mucus production yet reduces ciliary action
- smoking related damage to resp tissues (Bronchitis)
- viral LRTI damages resp tissues –> leads to bacterial LRTI
- Depletion of commensal organisms by anti microbial tx
- malformations (rare) and obstructions (e.g. tumours)
- Iatrogenic (tracheostomy, bronchoscopy)
Describe the pathogenesis of LRTI?
Access –> Resp tract is open to environment
Adherence –> pathogenic organisms have receptors for respiratory tissues
Invasion –> damaged resp tissues help invasion
Multiplications –> good nutritional environment for microorganisms
Evasions –> immune cells are present, damaged tissues help evasion
Resistance –> some bacteria causing LRTI have multi drug resistance
Damage –> causes bronchitis , pneumonia, septicaemia etc
Transmission –> easily passed out in resp. secretions
What are the specific clinical features of Bronchitis?
pathology
symptoms
signs
investigations
how common is sepsis?
Bronchitis
Pathology –> infection and inflammation of airways
Symptoms –> dysponea, cough, sputum and wheeze
Signs –> fever, tachypnoea, crackles and wheeze
Investigations –> hypoxia (possibly), normal CXR (usually)
Sepsis = uncommon
When are diagnostic criteria used in LRTI?
Diagnostic criteria are used to decide how to treat
CURB 65 –>
Confusion
Urea > 7 mmol/L
Respiratory rate > 30/ min
Blood pressure < 90 mmHg systolic or < 60 mmHg diastolic age ≥65 years old
If score > 1 leads to admission
if score > 2 –> IV treatment
Describe this CXR?
What structures can be seen?
Is it a normal looking xray?
Xray is slightly underexposed (should be able to see vertebral column throughout, only seen at the top).
Can see normal heart shadow, normal cardiothoracic ratio ( of 50%), normal costophrenic angles, lung hilum and vessels.
Slight shadowing showing the beginning of infection.
Describe the pathology shown (same pt as the previous xray with 12hrs inbetween)
- First Xray post 12 hrs –> shadowing all over the right lung and at the bottom of the left lung
- Second xray post 24 hrs –> complete whiteout, consolidation has spread rapdily, plus an endotracheal tube inside, needs ventilation in acute care unit
- Cause –> streptococcus pneumoniae, can spread rapidly and aggressively.
What is the pathology on this CXR?
Pleurisy at the right lower lobe.
On the left clear costophrenic angle, on the right it is not visible.
Patient will have pleuritic pain (Pleuritic chest pain is characterized by sudden and intense sharp, stabbing, or burning pain in the chest when inhaling and exhaling. For this patient will be localised to right lower lobe. )
What is the pathology shown on this pt’s cxr?
Right upper lobe, massive consolidation, also affecting the middle lobe of the r lung and the left upper lobe.
Right upper lobe, dark strip in the middle = air bronchogram, clearly visible because tissue around it is so consolidated the bronchiole is visible.
Pt actually had legionella infection.
What abnormalities are shown on this CXR?
- Two lung abcesses shown on the left lung –> most likely caused by staphylococcus aureus
- Right lower lobe –> pleural effusion, shown by curved fluid line, also some fluid shown in the horizontal fissure too.
- Tx –> abcess will respond to AB’s but pleural cavity will need to be drained.
what is the pathology shown on this xray?
What is the classic descriptive term for the pathology shown?
What is the likely cause of this type of sign on a cxr? What is the pathogen often invovled?
Given this pt has HIV was is the most likely infectious agent?
General haziness over both lungs, called a Ground glass opacity/ appearance.
Ground glass opacity = descriptive term referring to an area of increased attenuation in the lung on computed tomography (CT) with preserved bronchial and vascular markings
Suggestive of diffuse infection process, pneumonitis (diffuse pneunomia). Most commonly caused by viruses.
This pt actually has HIV, most common infective agent for pneumonitis = pneumocystis infection. Pneumocystis pneumonia (PCP) is a form of pneumonia that is caused by the yeast-like fungus Pneumocystis jirovecii.
This is CT scan of the previous pt
What pathology is evident?
Lung tissue on a CT scan is normally black only with only a few blood vessels.
A lot of inflammation is shown, diffusely spread in this pt.
Diffuse infection is difficult to see on CXR but more evident on CT.
What does this microscopy report from sputum sample show?
Shown:
Heamophilus, staph aureus, streptococcus all infected in this pt
Shown that the haemophilus influenzae bacteria are resistant to amoxicillin and coamoxyclav, however the other two are sensitive to all other antibiotics.
Describe the pathogenesis of sepsis
- Sepsis = inflammatory defence mechanism against infection
- Begins with stimulation of immune system, both innate and adaptive, leads to release of proinflammatory cytokines
- –> fever sx, vasodilation, ↑ capillary permeability, ↑ WBC no./activity, ↓ myocardial function
- Hypovolaemia, hypoxaemia, hypotension
- Hypoperfusion of tissues
- Anaerobic respiration and acidosis
- End organ damage and multi organ failure
Whar is the updated SIRS definition?
when is severe sepsis suspected?
Within 1 hr of suspected severe sepsis what should you do?
W/in 1 hr of suspecting severe sepsis need to give SEPSIS SIX CARE BUNDLE
1) High flow o2
2) Take blood culture
3) Give empirical IV AB’s
4) measure FBC and serum lactate
5) start IV fluid rescucitation
6) Start accurate urine output measurement
