Respi patho Flashcards
What holds open the large airways?
Cartilage
What controls the calibre of the small airways?
Smooth muscles
What type of cells line the alveoli?
Type 1 pneumocytes
Fn of type 2 pneumocytes
Produce surfactant
Repair of alveolar damage
What perforates alveolar walls?
Pores of Khon
Fn of pores of Khon
Permit passage of exudate and bacteria btw adjacent alveoli -> enable infection to spread
Requirements for lung to freely exchange O2
Alveoli must be open
- surface tension kept low
Lungs must be compliant
- easy to stretch and expand
Air must move freely
Sufficient area for diffusion
Barrier to diffusion must be thin
What is rhinitis?
URTI
Inflammation of the nasal cavity
Usually viral in origin
Pathogenesis of rhinitis
Viral necrosis of surface epithelial cells -> exudation of fluid and mucus from the damaged surface
Submucosal oedema -> swelling and nasal obstruction
Infection can spread to lower tract -> predispose to bacterial infection
What is allergic rhinitis?
Hypersensitivity to environmental agents
Pathogenesis of allergic rhinitis
Antigenic stimulus persists -> mucosa becomes swollen and polypoid w/ formation of nasal polyps
What are nasal polyps?
Localised outgrowths of lamina propria due to accumulation of oedema fluid, inflammation and fibroblast proliferation
Features of nasal polyps
Multiple
Bilateral
Involve nasal cavity and paranasal sinuses
Amt and composition of inflammatory component highly variable
Take shape of nasal cavity
What is sinusitis?
URT
Inflammation of the paranasal sinus linings of the maxillary, ethmoid and frontal sinuses
Pathogenesis of sinusitis
Mucosal oedema -> impaired drainage of secretions -> predispose to sec bacterial infection
Severe -> spread to meninges
What is the nasopharynx?
Part of pharynx lying immediately behind nasal cavities
- inaccessible -> hard to detect tumor until it’s grown in size
What lines the nasopharynx?
Respiratory columnar epithelium
w/ associated mucosa-associated lymphoid tissue
Is nasopharyngeal carcinoma (NPC) common in SG?
Yes
3 histological classification of NPC
Non-keratinising carcinoma
Keratinising squamous cell carcinoma
Basaloid squamous cell carcinoma
Characteristics of non-keratinising NPC
Tumor is poorly differentiated
Intermingled lymphocytes amongst carcinoma cells
Diff appearance to other squamous cell carcinoma of the head and neck
Characteristics of keratinising NPC
Resembles squamous cell carcinoma of other sites in the head and neck region
Associated w/ smoking and alcohol consumption
Risk factors for NPC
Epstein Barr Virus (EBV) infection at young age
Salt-preserved food
Family history
Features of EBV infection
Subclinical in childhood
Virus associated w/ later development of several malignancies
Infection in adolescence more likely to be symptomatic
Infects and maintain latency in nasopharyngeal epithelium and tonsillar B lymphocytes
Link btw NPC and EBV
NPC pts have elevated Ab titres to EBV viral antigens
- Ab titres precede tumor development by several years, correlated w/ tumor burden, remission and recurrence
- further linked to development of NPC thru EBV DNA, RNA and/or gene pdts in tumor cells
EBV stimulates normal cell to divide -> cancer
Basis of screening test for NPC
Ab against viral capsid antigen
Why may NPC originate from a single progenitor cell infected w/ EBV b4 clonal expansion?
EBV episome is identical in every tumor cell
Symptoms of NPC
Increased diplopia due to invasion of VI cranial nerve
Increased nasal obstruction, epistaxis, serous nasal discharge
Increased metastases in cervical lymph nodes
Pathogenesis of C. diptheriae infection
Infect upper airway mucosa -> produce exotoxin -> necrosis of epithelium -> pseudomembrane -> airway obstruction
What does H. influenzae infection cause?
Acute epiglottitis -> airway obstruction (due to swelling of epiglottis)
Compulsory vaccinations in SG
Diphtheria and measles
Vaccination for C. diphtheriae and H. influenzae
DTaP-IPV + HIB
Most common pathogen for acute pharyngitis and laryngitis
Virus
Symptoms related to larynx
Sore throat
Hoarseness
Cough
Tracheal soreness
What is stridor?
Breathing sound due to large airway obstruction, usually worsen in inspiration
What is croup in children?
Cough + stridor due to infection
What are some complications of URTI
Indivs w/ poor cough reflex (i.e: elderly/debilitated/unconscious) -> infected material not coughed up -> pass into smaller airways and rest of lung -> bronchopneumonia
What is allergic pharyngolaryngeal oedema?
Life-threatening type 1 hypersensitivity rxn
- may be associated w/ facial oedema and bronchospasm
How is acute toxic laryngitis acquired?
Via inhalation of toxic gases
Impt cause of death in fires
Acute toxic laryngitis
Risk factor for chronic laryngitis
Heavy smoker
How does chronic laryngitis lead to cancer?
Chronic irritation of epithelium -> squamous metaplasia -> increased risk of dysplasia and squamous cell carcinoma
What are singer’s nodules?
Benign lesions of the larynx
- reactive nodular thickenings of vocal cords seen in singers and chronic smokers
Where does carcinoma of the larynx occur?
Occur at/above/below level of vocal cords
Presentation of glottic tumors
Early
Hoarseness (change of voice)
Lower stage at presentation compared to supraglottic and subglottic tumors
Why do glottic tumors tend to be lower stage at presentation compared to tumors at the supraglottic and subglottic tumors?
Poor lymphatic supple of glottic region -> less likely to spread
Growth patterns of carcinomas
Polypoid -> space occupying
Ulcerative
What is atelectasis?
Collapse of the lung
Complications of atelectasis
Inadequate expansion of lung -> loss of lung vol -> affect ventilation
Causes of atelectasis
Resorption atelectasis
- airway obstruction
- air will get absorbed from alveoli but no replenishing of fresh air -> alveoli collapse
Compression atelectasis
-air/fluid in pleural space w/ compression of lung
-post-operative poor lung expansion
Contraction atelectasis
- scarring of lung/pleura
- loss of normal surfactant
What are the normal defences of the lung?
Mucus -> trap large microbes in URT
Ciliary action -> transport trapped microbes to back of throat where swallowed
Cough reflex
Alveolar macrophage -> phagocytose smaller organisms
Features of URTI
Common
Usually self-limiting viral disease
Bacterial vs viral infection of URTI
Bacterial infection is more serious
What can damage hose defences?
Smoking
Intubation
Previous infection
Factors that increase chance of infection
Poor swallowing and reduced cough reflex
Common pathogen for bronchitis and bronchiolitis
Viruses
- same ones that cause URTI
What is pneumonia?
Infective inflammation and consolidation of lung
- filling of airspaces by inflammatory exudate -> renders affected area solid and airless
What is pneumonitis?
Inflammatory disease dominated by interstitial inflammation
Causes of pneumonitis
Infection
Inhaled toxins and allergens
Drug rxn
Irradiation
Connective tissue disease
What is bronchopneumonia?
Primary infection centered on the bronchi, spreads to involve adjacent alveoli
Features of bronchopneumonia
Initially patchy, may become confluent
Common in infancy and old age
Affects lower lobe more
Terminal in debilitated pts
Lobar vs bronchopneumonia
Lobar pneumonia has no bronchial-lobe centric appearance
- infection confined to alveolar spaces
Pathogenesis of lobar pneumonia
Organisms gain entry to distal airspaces rather than colonising bronchi -> spread rapidly thru alveolar spaces and bronchioles (more virulent) -> infect whole lobe
- NOTE: little tissue destruction
Common organisms causing lobar pneumonia
S. pneumoniae
Klebsiella
What is an air bronchogram?
Phenomenon of air-filled bronchi being made visible by opacification of surrounding alveoli
What kind of organisms cause community-acquired pneumonia (CAP)?
Gram pos
-eg
- S. pneumoniae
- H. influenzae
- Legionella
- Mycoplasma
- M. tuberculosis
What kind of organisms cause hospital-acquired pneumonia (HAP)?
Gram neg
- eg
- Klebsiella
- Pseudomonas
- E coli
Risk factors for HAP
Being on a ventilator
How do you directly sample a lung?
Bronchoalveolar lavage (BAL)
What is tuberculosis?
Chronic pneumonia that is communicable, granulomatous
What organism causes tuberculosis?
Mycobacterium tuberculosis
Diseases that increase risk of tuberculosis
Diabetes
Chronic lung disease
Alcoholism
HIV infection
Features of mycobacteria
Slender rod-shaped bacteria
Waxy cell wall -> resistant to destruction by neutrophils
- only macrophage can effectively phagocytose and contain mycobacteria
Can live intracellularly -> proliferate in macrophages
Readily bind Ziehl-Neelsen stain
Resist decolourisation (AFB)
Pri vs sec TB
Pri
- no prev exposure (unsensitised host), pattern of disease
Sec
- prev exposure and sensitised, pattern of disease
Main diff is where the immune rxn is predominant
Prev exposure but poor immune sys = pattern of pri TB
Outcomes of TB
Both pri and sec TB may heal/spread
- TB spread via bronchi, lymphatics/into pleural space
Miliary TB
- TB enters blood supply
Describe the cell-mediated immunity of TB
Host develops targeted cell-mediated immunity
Antigens presented to CD4+ T cells -> secrete cytokines and activate macrophages to kill bacteria
Immune response comes at cost of hypersensitivity and accompanying tissue destruction
Pathogenesis of pri TB
Infection and necrosis at periphery of the lung, often just beneath the pleura -> Ghon focus
- small focus of infection due to few immune recognition sites within lung
Bacteria conveyed to local lymph nodes at lung hilum -> immune recognition -> enlarge through granulomatous inflammation and caseation (necrosis)
- immune recognition ONLY at lymph nodes at hilum
- lesions are small
Control of infection for pri TB
Cell-mediated immunity controls infection
Area of caseation heals -> only leave small calcified nodule at site of infection
Viable organisms lie dormant in these foci -> latent TB
- can’t transmit organism to others
Progression of pri TB
Progress w/ severe pneumonia and dissemination (uncommon)
Continuing enlargement of caseating granulomas in lymph nodes
Spread occurs by enlarging nodes eroding either thru the wall of a bronchus/thin-walled blood vessel
Distinctive pattern of miliary TB on chest x-ray
Many tiny spots distributed throughout the lung fields
- doesn’t follow airway
Pathogenesis of sec TB
Common presentation in immunocompetent adults
New organism/re-activate pri complex years aft pri infection
Occurs in apex of lung but if other organs seeded during pri infection -> re-activate elsewhere
Reactivation -> rapid mobilisation of defence rxn at site of entry and increased tissue destruction -> cavitation
Immune sys recognises infection in lung and tries to contain it there -> little lymph node involvement
Apical lesions (Assmann focus) begins as central area of necrosis surrounded by granulomas
Histopathology of focus of TB infection
Granuloma
Laanghan’s giant cell
T lymphocytes
Outcomes of sec TB
Vigorous immune response -> healing of apical lesions -> central area of caseous necrotic material surrounded by thick, dense collagenous wall which often calcifies (fibrocaseous TB)
Weakened immune response and residual organisms present -> latent TB lead to spreading infection -> reactivated fibrocaseous TB
Progression of sec TB
Poor immune response -> progrossive enlargement of apical lesion w/ continued destruction of lung tissue -> risk of erosion into blood vessels/airways
Spread is similar to pri TB (bronchopneumonia, miliary TB)
Risk factors for aspiration pneumonia
Unconsciousness
Impaired swallowing
Pathogenesis of aspiration pneumonia
Mixed organisms (commonly anaerobes and oropharyngeal bacteria) +/- gastric acid +/- food -> infective pneumonia + chemical damage
Frequently leads to lung abscess
Features of atypical pneumonia
Pt has symptoms of pneumonia but there is absence of consolidation on x-ray
Marked infiltration of alveolar septa/interstitium by chronic inflammatory cells
What are some organisms that cause atypical pneumonia?
Mycoplasma
Chlamydia
Rickettsia
Describe the immune rxn of viral pneumonia
Interstitial inflammatory response dominated by lymphoid cells
Severe -> cytokine storm -> acute respi distress syndrome
Common pathogens for viral pneumonia
Influenza
- H5N1
Sars-CoV-1/2
What are some traits of pneumonia caused in immunocompromised pt?
Caused by opportunistic pathogens
- pathogens that normally won’t cause infection in immunocompetent hosts
Common pathogens can cause more severe pneumonia
Disease disseminated early
Situations where organisms of low pathogenicity can cause infection?
Immunocompromised pts
Pts w/ prev damage to lung resulting in stagnant secretions
Presenting illness of HIV+ pts
Opportunistic infections
- Pneumocystis jirovecii
- Candida
What is bronchiectasis?
Permanent abnormal dilatation of the main bronchi
Complications caused by bronchiectasis
Airways dilated -> may contain purulent secretions, chronic inflammation of wall w/ loss of normal epithelium
Pts have recurrent infection
Haemoptysis (cough up blood)
Spread of infection from bronchi to surrounding lung
2 main factors predisposing to bronchiectasis
Interference w/ drainage secretions
Recurrent and persistent infection
Outcomes of bronchiectasis
Chronic suppuration w/ its sequelae
Spread of infection beyond lung
Massive haemoptysis
Loss of normal lung tissue w/it sequelae -> respi failure
What is a lung abscess?
Localised area of suppurative necrosis, usually forming large cavities
What are some infections predisposing pts to lung abscess?
Pulmonary infarction
Aspiration
Bronchial obstruction
Bronchiectasis
S. aureus
What are the main complications of lung abscess?
Rupture into pleura -> empyema and pneumothorax
Haemorrhage from erosion into pulmonary vessel
Bacteraemia
Obstructive vs restrictive lung disease
Obstructive
- limitation of airflow -> affect ventilation
- normal total lung capacity
- reduced expiratory flow rate
Restrictive
- total lung capacity reduced,
- normal expiratory flow rate
What does spirometry measure?
Lung vol and flow rate of air
- distinguish btw obstructive and restrictive lung disease
Features of obstructive lung disease
Problem w/ ventilation, usually at level of small branches of bronchial tree
Exhalation usually more affected and req more effort
Wheeze heard
What is obstructive sleep apnoea (OSA)?
Ep of partial/complete closing of the upper airways during sleep
- pt wake up repeatedly to gasp for air
- jaw and tongue fall backward and obstruct airway
What can OSA result in?
Hypoxaemia
Poor sleep
What is asthma?
Chronic disease affecting bronchioles
- recurring ep of bronchospasm (reversible) and excessive production of mucus
Precipitating factors for asthma attacks
Atopic -> allergens
Non-atopic -> hypersensitive airways and irritants trigger attack
What can repeated ep of asthma cause?
Over-reactivity of airways
Remodelling of airways
What is status asthmaticus?
Prolonged bronchospasm and mucus plugging -> respi failure
- no time for body to be oxygenated btw attacks
What is ‘model’ asthma?
Complex inflammatory response in bronchial mucosa
Pathogenesis of ‘model’ asthma
Prev sensitisation causes IgE mediated response -> activation of mast cells and direct stimulation of nerve receptors
Mast cells release chemical mediators -> recruitment of eosinophils, cause bronchoconstriction and increase in vascular permeability and mucus secretion
Recruited eosinophils and T helper cells release further mediators -> amplify and sustain inflammatory response
Structural changes in asthma
Hyperactivity and hypertrophy of smooth muscle bronchus
Hypersecretion of mucus
Mucosal oedema
Infiltration of bronchial mucosa by eosinophils, mast cells, lymphoid cells and macrophages
Deposition of collagen beneath bronchial epithelium
Which grp of people are predisposed to COPD?
Chronic smokers
Diff btw asthma and COPD
In COPD, airflow limitation is not fully reversible and disease is usually progressive (slow reduction to respi capacity)
Exacerbation of COPD
Relatively mild concomitant illness/poor air quality
- due to loss of normal lung fn
3 main pathologies contributing to COPD
Emphysema (affect alveoli) -> destruction of airspaces and loss of elastic recoil -> reduction in gas exchange capacity
Chronic bronchitis -> mucus hypersecretion and luminal narrowing of airways
Bronchiolitis -> narrowing of small airways by inflammation and scarring
What is emphysema?
Permanent dilatation of airspaces distal to the terminal bronchiole w/ destruction of tissue in absence of scarring
Pathogenesis of emphysema
Parenchymal destruction by extracellular proteases/elastases
Normally proteases secreted by inflammatory cells are inactivated by extracellular protease inhibitors in the lung but cigarette smoke inhibits effect of protease inhibitors, alpha-1-antitrypsin -> tissue destruction
Free radicals from cigarette smoke cause tissue damage
Persistent irritation -> increased inflammatory cells in lungs -> increased release of mediators and enzymes
Who is at risk of developing emphysema?
Pts w/ congenital alpha-1-antitrypsin deficiency
Clinical definition of chronic bronchitis
Cough productive of sputum on most days for 3 months of year for at least 2 successive years
What is chronic bronchitis?
Airway obstruction related to luminal narrowing and mucus plugging, resulting in alveolar hypoventilation
What is bronchiolitis?
Inflammation of airways <2mm in diameter
What happens in bronchiolitis?
Macrophages and lymphoid cells infiltrate airway wall
May progress and lead to scarring and narrowing of airways -> functional airways obstruction
Risk factors for COPD
Lifetime smoking exposure
Less common:
- recurrent childhood infections
- occupational exposure to dust
Common causes of death for pts w/ COPD
Respi failure
Sec right heart failure
What are diffuse parenchymal lung diseases?
Grp of lung diseases characterised by widespread inflammatory pathology, predominantly in interstitium -> reduced compliance in lungs
- acute/chronic/progressive
Main histological patterns of rxn in lung following damage
Haemorrhage and fibrin exudation into alveoli -> hyaline membranes (glassy, uniformly pink)
Oedema and inflammation of interstitium
Macrophage accumulation in alveolar spaces
Fibrosis in interstitium/alveolar spaces
What is acute respi distress syndrome (ARDS)?
Severe form of acute lung injury
- acute form of diffuse parenchymal disease
Clinical syndromes caused by alveolar and capillary damage
Most common cause of ARDS
Systemic sepsis
Severe trauma/burns
Inhalation of toxic fumes -> damage both endothelial and epithelial cells
Pathophysiology of ARDS
Injury of penumocytes and pulmonary endothelium -> damage to alveolar lining cells/alveolar capillary endothelium -> interstitial edema and high protein exudation into alveoli (hyaline membrane) -> regeneration of type 2 alveolar lining cells and inflammation of interstitium -> interstital fibrosis
Death in acute phase occurs due to interstitial edema and high protein exudation into alveoli
Fibrosis
- mild -> recovery w/ minimal residual respi dysfunction
- severe -> marked interstitial fibrosis (honeycomb lung) -> death due to chronic severe respi impairment
Phases of ARDS
Acute exudative phase
- interstitial oedema and high protein exudation into alveoli -> fibrin-rich fluid + necrotic epithelial cells -> hyaline membranes
Late organisation phase
- regeneration of type 2 alveolar lining cells, organisation of hyaline membranes w/ fibrosis
Causes of diffuse parenchymal lung disease
ARDS
Atypical pneumonias
Sarcoidosis
Smoking-related
Idiopathic
NOTE: these are only some of the many
What is honeycomb lung?
End stage chronic pulmonary fibrosis
How does honeycomb lung lead to death?
Leads to chronic respi impairment and reduced diffusion capacity -> death due to combination of respi and cardiac failure
Histopathological features of honeycomb lung
Holes are bigger and thicker (like honeycomb)
What is idiopathic pulmonary fibrosis?
Commonest chronic diffuse parenchymal disease
Progressive restrictive lung disease
What does lung biopsy show in idiopathic pulmonary fibrosis?
Usual interstitial pneumonia (UIP) pattern
What is hypersensitivity pneumonitis/extrinsic allergic alveolitis?
Lung disease due to hypersensitivity to inhaled organic antigens
What does hypersensitivity pneumonitis/extrinsic allergic alveolitis cause?
Chronic fibrosing lung disease
Most common grp of allergens for hypersensitivity pneumonitis/extrinsic allergic alveolitis and the clinical problems caused
Animal proteins and microbial agents in veg matter
Acute (respi symptoms 4-8h aft exposure)/chronic (insidious development of pulmonary fibrosis in pt that has not exp acute symptoms)
What is pneumoconiosis?
Disease of lungs caused by inhalation of dust
- interaction of dust w/ defence mechanism of lung -> inflammation -> release of cytokines -> stimulation of fibrosis
- worsened by smoking
Common particles associated w/ pneumoconiosis
Silica
Coal dust
Asbestos
*all are occupational hazards and have characteristic radiological and histological features
Features of asbestos
Fibrogenic
Oncogenic
Persist in lungs
Lung diseases associated w/ asbestos
Pleural plaques
Pleural effusions and thickening
Asbestosis -> progressive chronic lung fibrosis
- increase chance of mesothelioma
What are granulomas?
Histological manifestation of cell mediated immunity -> activated macrophages necessary to tackle intracellular bacteria, large organisms and foreign material
Causes of granulomas in lung
Infection (eg: TB)
Foreign material/antigens
Why are granulomas often seen in lymph nodes?
Immune recognition takes place in draining lymph nodes
What is sarcoidosis?
Systemic disease of unknown cause characterised by non-necrotising granulomas in many tissues and organs (eg: spleen, liver, bone marrow, etc)
Common site of metastasis from other cancers
Lung
Correlation btw smoking and lung cancer
Risk of cancer increases w/ no. of cigarettes smoked and age at which smoking was started (pack years)
Passive smokers have double risk compared to those not exposed
Stopping smoking reduces risk but doesn’t return to normal
Classification of lung cancer
Small cell carcinoma (SCLC)
- aggressive
Non small cell carcinoma (NSCLC)
- squamous cell carcinoma
- adenocarcinoma
- others
Location of lung cancer
Central -> near airways
Peripheral -> far from airways
Possible spread of lung cancer
Local
Lymphatic
Transcoelomic (pleural and pericardial effusions)
Hematogenous
Histological features of squamous cell carcinoma
Central cavitation
Preceded by squamous metaplasia/dysplasia
Features of squamous cell carcinoma
Commoner in males
High association w/ smoking
Features of adenocarcinoma
Equal gender incidence
Not strongly linked w/ smoking
- most common lung cancer in non-smokers
Minimally invasive
Spreads along alveolar septa
Looks like consolidation rather than mass on x-ray
Features of small cell carcinoma
Central
Rapid rate of growth
High association w/ smoking
Poor prognosis
Tumor cells show neuroendocrine differentiation
Histological features in small cell carcinoma
Enlarged nuclei w/ little cytoplasm
Why does lung cancer usually have poor prognosis?
No early symptoms
Many lesions found on chest x-ray screening have alr spread
Only way to pick up small lesions is by CT scan
Metastatic spread present in most pts at presentation
Associated syndrome w/ lung cancer
Paraneoplastic syndrome -> immune rxn to cancerous tumor
Outcome of NSCLC
Surgery is best hope of cure if cancer hasn’t spread out of lung
Most cases inoperable
Outcome of SCLC
Sensitive to radiotherapy and chemotherapy
What kind of cells line the pleura?
Mesothelial cells
Describe fluid cycle in pleura (bad phrasing of qn)
Constant generation of fluid from parietal pleura and resorption by visceral pleura
Transudate vs exudate
Transudate
- low protein fluid -> due to high hydrostatic pressure, low oncotic pressure
- little cells
Exudate
- high protein fluid -> due to damaged vessel walls/inflammatory rxn to tumor/infection
- lots of cells
Common causes of pleural effusions
Cardiac failure
Infections
Neoplasm
Diagnosis of pleural effusion on chest x-ray
Loss of air in costal phrenic angle
What is pleurisy?
Acute inflammation of the pleura, usually due to infection
Histopathological features of pleurisy
Fibrinous/purulent exudate seen on pleural surface
Neutrophils predominate in most bacterial infection (except: TB -> lymphocytes predominate)
Fibrinous exudate organised to form fibrous pleural adhesions
Common causes of pneumothorax
Thin, young mem
Congenital subpleural apical bleb
Rupture of emphysematous bulla
Asthmatics
Trauma
Iatrogenic (illness caused by medical examination or treatment)
Features of pneumothorax in chest x-ray
Lack of lung markings
Most common tumor of the pleura
Metastatic carcinoma
Pri neoplasm associated w/ asbestos exposure
Malignant mesothelioma
Features of malignant mesothelioma
Tubular (epitheloid)/spindle cell (sarcomatoid) pattern
Spread ard lung and mediastinal structures
Poor prognosis
Common mediastinal mass lesions adults
Metastases
Pri TB
Thymoma
Lymphoma
- specifically -> T cell lymphoblastic lymphoma, pri mediastinal large B cell lymphoma and Hodgkin lymphoma
Germ cell tumors
Common mediastinal mass lesions adults
Lymphoma/leukaemia
Neuroblastoma/other neural tumors
What kind of cells make up the thymus?
Lymphoid cells and specialised epithelial cells
What happens to the thymus as one ages?
Regresses after puberty
How does thymic tumors present and what are the main tumors of the thymus?
Anterior mediastinal masses
Main tumors
- thymoma
- lymphoma
- germ cell tumor
What is thymoma?
Neoplasm derived from thymic epithelial cells
- lymphocytes preset but are non-neoplastic
- proportion of cases associated w/ myasthenia gravis
Histological features of thymoma
Nest of epithelial cells
Lymphocytes
What is atresia?
Condition in which an orifice/passage in the body is abnormally closed/absent
Common developmental abnormalities causing lung disease in children
Bronchial atresia
Bronchogenic cysts -> accessory bronchial buds which become sealed off from the rest of airway
Bronchopulmonary sequestration -> area of lung tissue that develops abnormally (no connection w/ bronchial tree) -> no respi fn
Alternative name for neonatal respi distress syndrome
Hyaline membrane disease
Pathogenesis of neonatal respi distress syndrome
Deficiency of surfactant in lungs usually due to prematurity -> alveoli collapse -> hypoxia, damage to endothelial and alveolar lining cells and fibrin exudation
Childhood diseases that affect fn of lungs
Immotile cilia fn -> cilia have abnormal structure/can’t beat in coordinated pattern
Cystic fibrosis -> production of abnormally viscous mucus that can’t be cleared -> repeated infections and bronchiectasis
- autosomal recessive
Main cause of pulmonary oedema
Pulmonary capillary pressure due to left heart failure
Common symptom of pulmonary oedema and pathophysio behind it
Capillary rupture -> leakage of RBC into interstitium -> RBC phagocytosed by alveolar macrophages (heart failure cells)
Causes of pulmonary arterial hypertension
Sec to left heart disease where pressure is transmitted to entire pulmonary sys
Shunts from left to right heart
Chronic lung disease
Sequelae of pulmonary emboli
Unknown cause
Consequences of pulmonary hypertension
Sustained increased pulmonary arterial pressure -> irreversible structural changes in pulmonary arteries -> medial hypertrophy in muscular arteries and intimal proliferation -> narrowing/occlusion -> further increased pressure
What is cor pulmonale?
Heart failure sec to lung disease
- long term need to pump at higher pressures causes heart to fail
Outcome of pulmonary emboli
Depends on size of thrombus and local haemodynamics
- large -> circulatory collapse
- infarction
- no infarction but ventilation-perfusion mismatch
- recurrent small thromboemboli -> organisation of thrombi in small arteries -> permanent occlusion -> progressive reduction in pulmonary vasculature -> pulmonary hypertension
What is pulmonary vasculitis? What are some eg of diseases w/ prominent lung manifestations?
Inflammatory destruction of blood vessels ->bleeding into lungs
- repeated ep -> vessel damage -> pulmonary hypertension
Granulomatosis w/ polyangiitis (GPA) = Wegener granulomatosis
Eosinophilic granulomatosis w/ polyangiitis (EGPA) = Churg-Strauss syndrome
What is respi failure?
Inadequate gas exchange due to dysfn of 1/more of essential components of respi sys
Consequence of respi failure
Inability to maintain O2 and/or CO2 lvls at normal lvls -> hypoxia/hypercapnia
Normal physio response to low pO2 lvls
Increased RR
Measurement of oxygenation
Pulse oximeter
Arterial blood gas
- more accurate
Components that may fail in respi failure
CNS and nerves
Chest wall/diaphragm
Airways
Alveolar-capillary units
Pulmonary circulation
Main symptoms of respi failure
Breathlessness
Consequences of hypoxia
Consequence of longstanding hypoxia
Pulmonary hypertension and sec right heart strain
Polycythaemia due to stimulation of erythropoietin release from kidney
- high lvl of RBC to compensate for hypoxia
Clinical definition of type 1 respi failure
Hypoxaemia w/o hypercapnia
- main problem is failure of alveolar-capillary units -> gas exchange affected more than ventilation
Clinical definition of type 2 respi failure
Hypoxaemia w/ hypercapnia
- have component of poor ventilation resulting in retention CO2
Why does type 1 respi failure often lead to type 2 respi failure?
Progression of disease/exhaustion of pt reach a point where compensatory measures fail
Exhaustion and insufficient O2 to brain -> ventilation problems w/ hypercapnia
What are the diff clinical phenotypes of respi failure in pts w/ advanced COPD
Pink puffers
Blue bloaters
Describe pink puffers
Pink complexion
Obv breathing effort -> just enough alveoli to stay alive but breathe hard to make sure each one is always ventilated
Emphysema is pri underlying pathology
Pt compensates for less surface area for gas exchange by hyperventilating
Few unventilated areas of lung -> CO2 retention no an issue
Describe blue bloaters
Chronic bronchitis is pri underlying pathology
Marked ventilation/perfusion mismatch -> unable to shift enough air -> blood leaving lungs not oxygenated
Poor ventilation -> hypoxaemia and hypercapnia
Heart works hard to perfuse lung more -> right heart failure
Slow process -> brainstem re-setting to tolerate levels of hypxaemia and hypercapnia
Principles of therapy for pts w/ COPD
Treat cause
Give O2
Bronchodilators
Assist ventilation when necessary
Principles of therapy for blue bloaters
Blue bloaters have dulling of CO2 reflex -> too much O2 reduce rate of ventilation and exacerbate problems -> need to control O2 delivery and monitor closely
