Respiratory p2 Flashcards
Where does tuberculosis infection tend to affect?
lung, lymph nodes and gut
What is Primary TB?
syndrome produced by M.Tuberculosis in those not previously affected
Describe the onset/location of primary tb
common sites: sub-pleural in the mid-zones of the lungs, in the pharynx or terminal ileum
mild inflammatory response at the site of infection followed by spread to regional lymph nodes
infection then spreads to hilarity, cervical or mesenteric nodes respectively
What is the primary complex?
infective focus + lymph node involvement
What is the ghon focus?
the infective focus in the lung
What happens 1-2 weeks after infection with M.Tuberculosis ?
Onset of immune sensitivity - tissue reaction at both sites of the primary complex changes to form caseating granuloma
In the majority of cases, these heal with fibrosis, and frequently calcify without therapy
What is the presentation of the patient at caseating granuloma stage?
asymptomatic or have a single enlarged LN that may be palpable if cervical
Viable bacteria may remain within walled off in the primary complex, giving latent TB
Describe the methods by which primary TB can become symptomatic
Ghon focus erodes through the visceral pleura to discharge organisms and cause TB pleurisy / pleural effusion
Enlarged hilar LNs can cause bronchial obstruction and collapse
The hilar lymph nodes can erode into bronchus and rupture (bronchopneumonia)
The enlarging nodes can erode into vessels, giving miliary dissemination to the lung or systemic dissemination (pulmonary vein)
What is post-primary (secondary) TB?
M.Tuberculosis re-infection in tuberculin-sensitive individuals
How does secondary tb occur?
infection can be from exogenous sources, or more commonly ‘reactivation’ from a healed primary complex
Immediate granulomatous response to the disease, thus regional lymph involvement is not common
in the lung, this creates a classical apical lesion termed an Assman focus, with destruction of lung parenchyma leading to cavitation
What are the outcomes of secondary TB?
Lesion may heal with fibrosis and calcification if the immune system is strong, or will progressively enlarge in those with poor immune systems
This has greater risks of eroding into vessels/airways and causing complications
What are the symptoms of TB?
non-specific: malaise, night sweats, anorexia, weight loss
When do specific symptoms of TB occur?
Late, in established disease:
productive mucoid cough
repeated small haemoptysis
pleural pain
Can present with pneumonia or pleural effusion. on examination there may only be a fever and apical crepitations, with late signs of consolidation or pleural effusion
patients may be clubbed in advanced disease
How can TB be coughed out?
release of tubercle bacilli into the main bronchus
Who are the high risk patients for TB?
endemic areas previously treated for TB close contact with TB immunosuppressive co-morbidities / drug tx live in overcrowded conditions alcohol/drug users
What are the investigations of active pulmonary TB?
SPUTUM sample: 3 x (1 in morning)
Microscopy(24h) + PCR + Culture (takes 6 weeks)
sputum grows acid-fast bacilli that stain red with Zeihl-Neelsen staining. This is mycobacterium tuberculosis and the diagnosis is TB.
If sputum = negative, bronchoscopy with biopsy or broncho-alveolar lavage may be useful
CXR: upper lobe cavitation, pleural effusions, lymphadenopathy
Ix for extra pulmonary disease as clinically indicated
What are the investigations for latent TB?
Mantoux test: TB antigen injected, size of wheal reaction monitored
>5mm = +VE in immunosuppressed, prior TB or recent contacts >10mm = +ve in those with risk factors for TB >15mm = +ve in any individual
Interferon gamma release assay: IGRA blood test also required to diagnose latent TB in immunocompromised individuals (can have false -ves in skin test)
What does a positive test for latent TB lead to?
Assessment for active TB
if no evidence, treat for latent TB
FBC, U+E, LFT to rule out other causes
screening for HIV, HEP B/C
What is the management of ACTIVE TB?
Admit - negative pressure side room OR
TB service within 2 weeks. do not delay referral
Assess risk factors for drug resistant TB
RIPE: Rifampicin + isoniazid 6 months with Pyraziname and ethambutol for first 2 months
If CNS involvement, R+I continued for 12 months
If poor adherence - given under key worker supervision
What are the risk factors for MDR TB?
previous tb treatment from endemic areas contacts with MDR-TB poor adherence to current treatment aged 25-45 HIV co-infection assess with PCR
How are household members managed if positive TB?
Notifiable disease:
All household members and close contacts should be traced and assessed for latent TB
Casual contact (work) should be traced only if the person with TB is particularly infectious (10% or more of close contacts develop TB) or if casual contacts are at increased risk of infection (healthcare workers/people with HIV)
What is the management of MDR-TB?
continue infection control measures until pulmonary / laryngeal disease has been excluded
treat with at least 6 drugs to which it is sensitive
What is the management of latent TB?
treat with 3 months of rifampicin and isoniazid (with pyridoxine)
What are the drug side effects of the TB treatment drugs?
Rifampicin: abnormal LFTs, pink urine (red-and-orange-pissin). Also a cytochrome P450 inducer
Isoniazid: peripheral neuropathy / encephalopathy. very rare when prophylactic pyridoxine co-prescribed (I’m-so-numb-azid)
Pyrazinamide: hepatotoxic
Ethambutol: optic neuritis, assess with colour vision testing (eye-tham-butol)
R, I and P all associated with hepatotoxicity
What symptoms are caused when TB bacilli settle and cause later disease?
Painless lymphadenopathy: lymphatic TB mono arthritis: joint/spinal TB sterile pyuria: renal TB Meningitic syndrome: TB meningitis Erythema nodosum / lupus vulgaris: cutaneous TB Chest pain: TB pericarditis
How does TB affect the world?
kills 2 million people/year worldwide
with 350 deaths/year in the UK
Most common cause of death in people with HIV
Most common drug resistance in UK = isolated isoniazid resistance
rifampicin = marker for multi-drug resistant TB
What is he presentation of pneumothorax?
May be asymptomatic in young patients or present with sudden onset of unilateral pleuritic pain, with progressive breathlessness
reduced expansion
increase resonance to percussion
decreased breath sounds and reduced vocal resonance
How does tension pneumothorax present?
Tracheal deviation away from side of pneumothorax
Reduced air entry to affected side
Increased resonant to percussion on affected side
Tachycardia
Hypotension
What are the classifications of pneumothorax?
Spontaneous: primary or secondary
traumatic: penetrating trauma, rib fractures
iatrogenic pneumothorax: lung biopsy, endoscopy, subclavian cancelation, positive pressure ventilation
How are primary / secondary pneumothoraces caused?
primary: lung parenchyma otherwise normal, caused by a rupture of the apical bleb, often in tall, thin young men
secondary: underlying lung disease / abnormality e.g. in COPD, pneumonia, CF, asthmatic, malignancy
What investigations are done for pneumothorax?
Expiratory CXR - trace the outline for areas devoid of lung markings and look for tracheal deviation
ABG: if signs of respiratory distress / chronic lung disease
What is a tension pnuemothorax?
air in the pleural space leading to cardiac compromise
a valvular mechanism allowing air entry to the pleural space during inspiration, but no air exit during expiration
Therefore more air keeps getting drawn into the pleural space with each breath and cannot escape
The intrapleural space is very high, deflating the lung and decreasing venous return to the heart
how is tension pneumothorax differentiated?
respiratory distress, pallor, haemodynamic compromise, distended neck veins, tracheal deviation
What is the treatment of TENSION pneumothorax?
100% oxygen
Insert a large bore cannula into the second intercostal space in the midclavicular line
CXR
Insert chest drain
What is the management for pneumothorax?
Primary:
if the rim of air is < 2cm and the patient is not short of breath - discharge
otherwise, aspiration should be attempted
if this fails (defined as > 2 cm or still short of breath) then a chest drain should be inserted
secondary:
> 50 years old and the rim of air is > 2cm and/or the patient is short of breath then a chest drain should be inserted.
otherwise aspiration should be attempted if the rim of air is between 1-2cm. If aspiration fails (i.e. pneumothorax is still greater then 1cm) chest drain
Management if pneumothorax <2cm
discharge
avoid strenuous exercise
Interval CXR every 2 weeks until resolution
quit smoking
Management if pneumothorax >2cm
attempt aspiration and admit for at least 24 hours
if this fails - chest drain
How is aspiration of pneumothorax done?
Insert a 16G cannula under local anaesthetic into second intercostal space, mid-clavicular line and attach to 3-way tap and a 50ml syringe to aspirate
stop when resistance is felt, or if the patient coughs excessively
Check with X ray
How Is a chest drain inserted?
Triangle of safety: 5th ICS, mid-axillary line and anterior axillary line, and chest X-ray to check positioning
the drain should be attached via tubing to the underwater seal, which must be below the level of the patient
check the drain is swinging with respiration, bubbling and then check positioning with repeat CXR
how should a patient be counselled following pneumothorax?
flying should be avoided for 6 weeks and diving should be permanently avoided
if there is recurrent pneumothorax surgery may be indicated, pleurectomy if fit, talc pleurodesis if not (some risk of recurrence)
What are the causes of pleural effusion?
empyema / pylothorax - accumulation of pus, due to infection
chylothorax - accumulation of lymph due to thoracic duct leakage
haemothorax - accumulation of blood, due to trauma
fluid effusion: transudative / exudative
What is the difference between transudate and exudate?
Transudate: occur due to increased hydrostatic pressure or decreased oncotic pressure (fluid shifting)
Exudates due to increased capillary permeability (Inflammation)
What are the causes of TRANSUDATIVE effusion?
Cardiac failure: LHF leading to increased hydrostatic pressure
Hypoalbuminaemia: Liver failure - decreased protein production decreasing oncotic pressure
Renal failure: nephrotic syndrome decreasing oncotic pressure
Peritoneal dialysis
Rarely: hypothyroidism, ovarian tumours
What are the causes of EXUDATIVE effusion?
infections: bacterial pneumonia, TB
neoplasm: lung primary or secondary, mesothelioma
pulmonary infarction: PE
Autoimmune infection: RA / SLE
Abdominal disease: pancreatitis, subphrenic abscess
What are the symptoms of pleural effusion?
asymptomatic, dyspnoea and pleuritic pain
What are the examination findings of pleural effusion?
Decreased Chest expansion, tracheal deviation away if large.
Stony dull to percussion
Decreased breath sounds - can be bronchial breathing
Reduced vocal resonance
Mediastinal deviation (in massive effusion)
What is the cause of empyema?
Bacterial invasion of the pleural space, either spreading into an exudative effusion from adjacent pneumonia or from direct inoculation (e.g. poor aseptic technique in chest drain)
What is the clinical presentation of empyema?
fever + signs of pleural effusion
Aspirated fluid is yellow and turbid, with pH <7.2, low glucose, high LDH
Requires ABX IV and chest drain
How are effusions investigated?
Unilateral, more likely to be exudative - bilateral more likely transudative
CXR - seen >300ml
USS - guide aspiration
Aspiration and LIGHTS CRITERIA
How are transudates / exudates differentiated?
exudates have a protein level >30g/L, transudates are <30g/L
If between 25-35, one positive element of LIGHTS = exudate
What is light’s criteria?
- pleural fluid protein divided by serum protein is >0.5
- pleural fluid LDH divided by serum LDH >0.6
- pleural fluid LDH more than two-thirds the upper limits of norma serum LDH
What is the management of pleural effusion?
if aspirated fluid = purulent, place a chest drain and consider IV antibiotics (or if PH is <7.2, also suggest empyema)
drainage should also take place if symptomatic, either with aspiration as per the diagnostic tap, or using an intercostal drain
Manage underlying cause
What is the peak age of onset of lung cancer?
65 years of age
M:F 3:1
What is the most common risk factor for lung cancer?
SMOKING
stopping smoking decreases the risk by one half in 5 years
other rf: passive smoking, urban living, occupational exposure
How are lung cancers classified?
small cell disease (20%) and non-small cell disease (80%)
