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🫁 Respiratory
Many of these diseases affect multiple pieces of anatomy; these are clarified within the disease section. However, to help your understanding, they’re classified within the primary piece of anatomy they affect.
Classifying by anatomy:
- Obstructive sleep apnoea occurs due to the relaxation of the throat muscles, blocking your airway during sleep.
- Collapse of the pharyngeal airway.
- Apnoea episodes are where the individual will stop breathing for up to a few minutes.
- Epworth Sleepiness Scale
- Snoring
- Daytime sleepiness
- Apnoea episodes (often reported by the partner)
- Waking up not feeling refreshed from sleep
- Concentration problems
- Sleep studies with ENT specialist / at a sleep clinic
- Oxygen saturation
- Heart rate
- Respiratory rate
- Breathing
- Lifestyle: Stop smoking, drinking alcohol and lose weight
- Continuous positive airway pressure (CPAP)
- Surgery: Uvulopalatopharyngoplasty (UPPP)
Sleeping while monitoring the:
- Haemophilus influenza type B infection causing swelling of the epiglottis.
- Thumbprinting sign: Shadowing caused by the swollen epiglottis
- ABCDE
- Immediate escalation to anaesthetics to secure the airway, this may be through intubation if possible or by tracheostomy as the swollen epiglottis may make intubation impossible.
- IV antibiotics (see local guidelines)
- Steroids, e.g. dexamethasone
Management:
- CPAP: Pushes only.
- Provides a fixed positive pressure on the airways through inspiration and expiration, maintaining airway patency.
- BiPAP: Pushes & pulls. Used in T2RF.
- This is used in CO₂ retainers when they can no longer maintain their respiratory drive. It pulls the CO₂ from the lungs as well as pushing O₂ in.
- COPD with respiratory acidosis
- Hypercapnic respiratory failure: Chest wall deformity, neuromuscular disease
Asthma is a chronic respiratory condition causing inflammation and narrowing of the bronchi.
- Dust
- Exercise
- Infection
- Time of day: Night or early morning
- Cold/damp
- Occurring in episodes
- Diurnal variation: Often worse at night.
- Wheeze
- Shortness of breath
- Atopy: Eczema, hayfever, food allergies
What makes up the following grades:
- PEFR: 50-75%
- PEFR: 33-50%
- RR ≥ 25
- HR ≥ 110
- Unable to complete sentences
- PEFR < 33%
- SpO2 < 92%
- Cyanosis
- Hypotension
- Exhaustion - PaCO₂ normal/high
- Silent chest
- Tachyarrhythmias
- pCO2 > 6 (Normal - represents exhaustion)
- ABCDE
- Nebulised salbutamol 5mg & ipratropium bromide
- K⁺ as can be ↓
- Steroids: PO prednisolone / IV hydrocortisone
- Antibiotics (if you suspect this is secondary to an infection)
- IV aminophylline
- IV salbutamol
- IV magnesium sulphate
- Admission to HDU/ITU for intubation & ventilation
- Stable on salbutamol inhaler for 24 hours
- PEFR > 75% predicted
Investigation:
- Fractional exhaled NO (FeNO): ↑ in airway inflammation
- Spirometry with reversibility
- Peak flow variability: measure peak flow multiple times a day for 2-4 weeks looking for variability throughout the day.
- Direct bronchial challenge test (with histamine or methacholine).
- Curschmann spirals: Shed epithelium becomes whirled mucus plugs
Note: Ask at your University which guideline protocol they follow in exams.
- BTS (2016):
- If high probability of asthma based on clinical picture, try treatment.
- If unsure, use spirometry with reversibility testing to confirm.
- If low probability, consider referring for other causes.
- NICE (2017):
- Advise not to make a diagnosis based on clinical picture.
- Always investigate at a diagnostic hub.
Management:
- Activate beta 2 adrenergic receptors on the smooth muscle that surrounds the airways → Smooth muscle to relaxation → Bronchodilation.
- SABA: Work within minutes, last several hours.
- LABA: Lasts at least 12 hours.
- Reduce airway inflammation, preventing or reducing asthma attacks → Prevents airway smooth muscle hypertrophy secondary to chronic inflammation.
- Block acetylcholine receptors blocking the parasympathetic effect of bronchoconstriction, indirectly causing bronchodilation.
- Leukotrienes → Inflammation, bronchoconstriction & mucus secretion.
- Blocking these prevents this.
Based on NICE Guidelines (2017):
- SABA
- Add regular low-dose ICS
- Add LTRA (review in 4-8 weeks)
- Add LABA (discuss if LTRA has helped at all, if not stop it)
- MART (maintenance & reliever therapy): Combined ICS (low-dose) & fast-acting LABA
- MART with moderate dose ICS
- Increase ICS to high-dose OR add PO theophylline OR add LAMA.
- Refer to specialist
- SABA - Salbutamol
- SAMA - Ipratropium
- ICS - Beclometasone, budesonide, fluticasone, mometasone
- LTRA - Montelukast
- LABA - Salmeterol, formoterol
- LAMA - Tiotropium
- MART - Turbohaler, spiromax
- ICS & LABA - Symbicort, fostair, seretide
- Inhaled drugs, theophylline and prednisolone can be taken as normal during pregnancy and breast-feeding.
Atelectasis is the complete or partial collapse of the entire lung, or a lobe of the lung due to airway obstruction.
- Mucus plug
- Secretions build up in airways due to reduced movement and because you can’t cough → Airrway obstruction → Bibasal lung collapse → Reduced lower lobe breath sounds
- Cystic fibrosis
- Asthma
- Foreign body: Inhaled object (e.g. peanut)
- Lung tumour within the airway
- Pleural effusion
- Pneumonia
- Pneumothorax
- Lung tissue scarring of lung tissue due to injury, lung disease or surgery.
- Tumor (non-airway) causing external compression
- Position patient upright
- Chest physiotherapy
- Damage and scarring of the large airways due to recurrent infection and resulting inflammation from immune response.
- Leads to mucus buildup and dysfunction of the mucociliary escalator.
- Multiple thin walled cystic space (ring opacities), several of which have air-fluid levels.
- Tram track sign
- Signet ring sign
- Cluster of grapes sign
COPD is chronic inflammation of the airways causing bronchitis (airway inflammation & narrowing) and emphysema (alveoli destruction).
- Shortness of breath.
- Cough.
- Wheeze.
- Recurrent LRTI.
- 'Pink puffer': Predominantly emphysema.
- Compensate for damaged alveoli by hyperventilating.
- High VQ ratio.
- 'Blue bloater': Predominantly bronchitis.
- Compensate for lack of air getting to the alveoli by increasing cardiac output.
- Low V/Q ratio.
- MRC dyspnoea scale. Scale of 1-5, useful to remember the extremes:
- SOB on strenuous exercise = 1.
- Unable to leave house = 5.
- Obstructive picture: FEV1/FVC ratio < 0.7
Using FEV1:
- Stage 1: FEV1 > 80% predicted
- Stage 2: FEV1 50-79% predicted
- Stage 3: FEV1 30-49% predicted
- Stage 4: FEV1 <30% predicted
- ABG: ↑ HCO₃⁻ → Chronic retainer
- TLCO: Total lung diffusion capacity
- KCO: Diffusion capacity of a single alveolus
What would they be in the following diseases:
- Both low
- KCO high (compensatory), TLCO reduced
- Both low
- KCO high, TLCO low
- Lack of lung expansion → Higher pressures in alveoli → More diffusion
- Bedside:
- Sputum culture: Tailor antibiotic regimen later.
- ECG
- Bloods:
- FBC: WCC to assess if infective cause, Hb to look for secondary polycysthaemia.
- Serum ɑ-1 antitrypsin
- Imaging:
- Chest X-ray: Exclude other causes.
- CT thorax: Exclude fibrosis and cancer.
- Prednisolone 30mg OD for 7-14 days
- Antibiotics (if infective cause)
- Regular inhalers
- Inhaled: Nebulised salbutamol and ipratropium
- Steroids: IV hydrocortisone or PO prednisolone
- Antibiotics (if likely infective cause)
- Chest physiotherapy to help clear sputum
- Non-invasive ventilation (BiPAP), may also need IV aminophylline
- Stage 1: SABA (salbutamol)/SAMA (ipratropium)
- Stage 2:
- No steroid features: LABA & LAMA
- Steroid features: LABA & ICS
- Stage 3:
- Triple therapy: LABA & LAMA & ICS (Trelegy ellipta, trimbo)
- Advanced management
- Bullectomy (removing the dilated airspaces)
- Lung volume reduction surgery
- Indicated in if on maximal medical therapy and still have marked ADL restriction. Must have:
- FEV1 > 20% predicted
- Upper lobe predominant emphysema
- PaO2 of < 7.3 kPa (measured when the patient is clinically stable, on two occasions, at least 3 weeks apart)
- PaO2 of 7.3 - 8 kPa & one of the following:
- Nocturnal hypoxaemia (SaO2 < 90%)
- Secondary polycythaemia
- Pulmonary hypertension (pulmonary artery pressure > 25mmHg)
- Peripheral oedema
- Annual pneumococcal & flu vaccine
- Malignancy - 1° or 2°
- Foreign Body
- Abscess / cyst
- Granuloma - Sarcoid / TB
- Pulmonary hamartoma / AVM
- Skin tumor
- Adenocarcinoma (~ 40%)
- Presents in non-smoking women (but still in smokers too)
- Best prognosis
- Squamous cell carcinoma (~ 30%)
- Present in the mediastinum, develop from the bronchi
- Hypercalcaemia - Secretes PTH
- Hypertrophic pulmonary osteoarthropathy (affects hands & feet)
- Large cell carcinoma (~ 10%)
- Likely to metastasise
- Carcinoid
- Neuroendocrine tumour secreting serotonin, histamine & bradykinin
- Bradykinin → Facial flushing
- Histamine → SOB
- Serotonin → Diarrhoea, asthma & SOB
- Urinary 5-HIAA
- Octreotide scan
- Somatostatin analogues: Octreotide
- Mesothelioma
- Pleural tumour associated with asbestos exposure with a long latent period of up to 45 years between exposure and cancer development.
- Aggressive, quickly metastasise, strongly related to smoking.
- Release neuroendocrine hormones, meaning they commonly cause paraneoplastic syndromes.
- Metastases from other sites
Name the paraneoplastic syndrome & tumour causing it:
- Recurrent laryngeal nerve palsy
- Upper lung tumour
- SVCO
- Upper lung tumour
- Horner's syndrome
- Pancoast (apical) tumour compressing the sympathetic ganglion
- SIADH
- SCLC secreting ADH causing dilutional hyponatraemia
- Cushing's syndrome
- SCLC secreting ACTH
- Hypercalcaemia
- Squamous cell carcinoma secreting PTHrP
- Lambert-Eaton syndrome
- SCLC
- Cough
- Shortness of breath
- Weight loss
- Haemoptysis
- CXR:
- Pleural effusion (usually unilateral - exudative)
- Mass
- Atelectasis
- Contrast-enhanced CT thorax, abdomen, pelvis (CT TAP):
- Confirm diagnosis & staging
- PET-CT may also allow us to more clearly see metastases
- Bronchoscopy with EBUS (endobronchial USS) with transbronchial needle aspiration for histology
- Lifestyle:
- Smoking cessation
- Medical:
- Chemotherapy: Metastases
- Radiotherapy: Can be definitive in adenocarcinoma (but surgery is preferred)
- Surgical:
- Lobectomy/segmentectomy → Localised disease (T1/2 N0 M0)
- Pneumonectomy/bi-lobectomy → Extensive disease
Infection of the lung tissue.
- Bacteria infect alveoli → Pulmonary membrane inflammation → Increased permeability → Blood & fluid entering alveoli causing consolidated appearance (filled with liquid)
CURB-65 (1 point for each of the following):
- Confusion: New disorientation to time, place or person
- Urea > 7
- RR ≥ 30 bpm
- BP < 90/60 mmHg
- > 65 years
- S. pneumonia (50%)
- H. influenzae (20%)
- Gram ⊖ coccobacilli
- Moraxella catarrhalis
- Immunocompromised patients
- Chronic pulmonary disease patients
Cases:
- Rash: Herpes labialis
- Pathogen: S. pneumoniae (Gram ⊕ diplococci)
- Pneumoncoccal urinary antigen
- CXR: Lobar consolidation
- H. influenzae (Gram ⊖ coccobacilli)
- Influenza
- Pseudomonas aeruginosa (Gram ⊖ bacilli)
- Staphylococcus aureus (Gram ⊕ cocci)
Lower respiratory tract infection (LRTI) developing > 48 hours after admission to hospital.
- P. aeruginosa (Gram ⊖ bacilli) - Associated with mechanical ventilation
- S. aureus (Gram ⊕ cocci)
- Enterobacteria:
- E. coli (Gram ⊖ bacilli)
- Klebsiella (Gram ⊖ bacilli)
Cases:
- S. aureus: Associated with flu, lymphoma/leukaemia, IVDU
- Klebsiella
- Stroke
- Myasthenia gravis
- Bulbar palsy
- Alcoholics
- Epileptics due to post-ictal state
- Lung abscess causing recurrent fever, finger clubbing and foul smelling breath
Pneumonia caused by an organism that cannot be cultured or detected using a gram stain.
"Legion of psittaci MCQ"
- Legionella
- Chlamydia psittaci
- Mycoplasma pneumoniae
- Chlamydydophila pneumoniae
- Q fever (coxiella burnetii)
Cases:
- Mycoplasma pneumonia. Rash → Erythema multiforme.
- Cold AIHA (see haematology) → ↑ RBC breadown → ↑ Bilirubin
- Mycoplasma serology
- Legionella
- Legionella → SIADH
- Urinary legionella antigen
- Clarithromycin
- Chlamydia psittaci
- Coxiella burnetii
- Pneumocystis jiroveci (see Infectious disease)
For all of these, the antibiotic choice depends on local guidelines. However, these are more commonly used.
- 0-1: Home, PO amoxicillin / clarithromycin 5 days
- 2: Admit, PO/IV amoxicillin & clarithromycin 7 days
- Penicillin allergy: PO/IV clarithromycin
- ≥ 3: ITU, IV co-amoxiclav/ceftriaxone/tazocin & clarithromycin
- < 5 days from admission: Co-amoxiclav
- > 5 days from admission: Tazocin / ciprofloxacin
- Sepsis
- Pleural effusion (exudative)
- Lung abscess
Case:
- Empyema → Chest drain & antibiotics
Fluid collection within the alveoli.
- Cardiogenic
- ↑ hydrostatic pressure in the pulmonary vessels (due to overload) → Transudative fluid in alveoli
- Heart failure
- Non-cardiogenic
- Acute lung inflammation → ↑ vascular permeability & ↑ hydrostatic pressure (due to vascular resistance) → Exudative fluid in alveoli
- ARDS: Sepsis, trauma, pancreatitis
- High altitude
- Opioid/salicylate toxicity
- PE
- Bats wing airspace shadowing
- Signs of heart failure:
- Alveolar oedema
- Kerley B lines
- Cardiomegaly
- Upper lobe diversion
- Pleural effusion
The interstitium is the tissue surrounding the alveoli, the tissue that oxygen moves across when passing from the alveoli to the blood, including alveolar epithelium, pulmonary capillary endothelium and basement membrane.
Diseases:
- Coal worker's lung
- Hypersensitivity pneumonitis
- Type III hypersensitivity to environmental allergen causing tissue inflammation (extrinsic allergic alveolitis).
- Lymphocytes
- Mast cells
- Bird-fanciers lung → Bird droppings
- Farmer's lung → Hay mold spores
- Malt workers lung → Mould on barley
- Ankylosing spondylitis
- Radiation
- Tuberculosis
- Sarcoidosis
- Idiopathic
- Bibasal fine crackles
- Finger clubbing
- Pirfenidone: Antifibrotic & inflammatory
- Nintedanib
- Connective tissue disorders (except ankylosing spondylitis)
- SLE
- RA
- Systemic sclerosis
- Drug-induced:
- Methotrexate
- Cyclophosphamide
- Amiodarone
- Bleomycin
- Asbestosis
- Asbestos is fibrinogenic (so induces fibrosis in the tissues) & oncogenic
- There is a gap between exposure & mesothelioma
- CT: "Ground glass appearance" / "Honeycombing"
- Lung biopsy
- Build up of inflammatory cells in the tissues forming non-caseating granulomas.
- It’s triggered by the immune system reacting to foreign substances (viruses, bacteria, chemicals)
- Erythema nodosum (painful)
- Parotid gland swelling
- Lymphadenopathy
- Hypercalcaemia: Macrophages inside the granulomas causing an increased conversion of vitamin D to its active form.
- Neurological: Bilateral facial nerve palsies
- Ocular: Anterior uveitis
- Cardiovascular: Heart block/arrhythmia
- Gastrointestinal: Hepatomegaly
- Dermatological: Lupus pernio
- Bedside:
- Spirometry: Restrictive picture
- ECG: Checking for heart involvement
- Bloods:
- FBC: Lymphopenia due to lymphocytes all clustered in tissues
- U&E: Abnormal if renal stones
- LFTs: Cholestasis or cirrhosis
- Calcium: Hypercalcaemia
- Serum ACE (Raised in 50%)
- Imaging:
- CXR
- Stage 0: No changes
- Stage 1: Bilateral hilar lymphandenopathy
- Stage 2: Lymphadenopathy with pulmonary infiltrates (presence of a substance denser than air)
- Stage 3: Pulmonary infiltrates alone
- Stage 4: Fibrosis
- Biopsy showing non-caseating granulomas
- Stage 1 (hilar lymphandenopathy):
- Conservative
- Stage 2 (pulmonary infiltrates):
- Prednisolone (40mg)
- Methotrexate / azathioprine
- 60% of patients with pulmonary sarcoidosis have symptom resolution at 2 years.
- 20% respond to steroids.
- 20% show no improvement.
The pleura is a double-layered serous membrane that covers each lung (visceral), and lines the thoracic cage (parietal). The pleural space sits between them contains a small amount of serous fluid.
Diseases:
This is an abnormal collection of air in the pleural space between the lung and the chest wall.
- Do they have an underlying lung condition?
- Cystic fibrosis, asthma, COPD.
- Are they short of breath?
- CXR: Size of pneumothorax
- Erect CXR
- At the level of the hilum, measure horizontally from the chest wall to the lung edge.
Cases:
- Right-sided rib fractures
How are the following patients managed:
- Conservative
- Aspirate with a 16-18G cannula under local anaesthetic
- Insert chest drain
How are the following patients managed:
- Conservative
- Aspirate
- Chest drain
- Chest drain
- Tension pneumothorax occurs when there is a one-way valve that allows air into the pleural space, but does not allow it out. This causes the pressure to build up and is a very severe, life-threatening condition.
- Tracheal deviation.
- Absence of lung markigs in the left upper zone.
- Collapse of the left lung secondary to the pressure exerted by the pneumothorax.
- ABCDE
- Needle decompression using a 16-gauge cannula (gray) inserted at the second intercostal space, mid-clavicular line.
- Insert just above the third rib to avoid damage to neurovascular bundle
- Chest drain
- Chest drain, sited within the triangle of safety.
- Triangle of safety borders: 5th intercostal space, mid axillary line, anterior axillary line.
A buildup of fluid within the pleural space.
- Triangle of safety: Space between the base of the axilla, lateral edge pectoralis major, 5th intercostal space and the anterior border of latissimus dorsi
- INR > 1.3
- Platelet count < 75
- Pulmonary bullae
- Pleural adhesions
- Thoracocentesis (aspirate fluid):
- Exudate vs transudate
- Protein < 25 → Transudate. Protein > 35 → Exudate
- LDH: Pleural fluid LDH is > 2/3 the upper reference limit for serum LDH in exudative
- Culture
- Cytology (Malignancy)
- Glucose (↓ in RA)
- NT-proBNP (↑ in HF)
- Unilateral always requires thoracocentesis whereas if bilateral is with HF symptoms & signs then it is only done if medical therapy is unsuccessful.
- HF would be investigated with a transthoracic ECHO
- Infection (most common exudate): Pneumonia, TB, subphrenic abscess
- Connective tissue disease: RA, SLE
- Neoplasia: Lung cancer, mesothelioma, metastases
- Pancreatitis
- PE
- Dressler's syndrome
- HF (most common transudate)
- Hypoalbuminaemia: Liver disease, nephrotic syndrome, malabsorption
- Hypothyroidism
- Meigs' syndrome: Ovarian tumour
- ? malignant pleural effusion
The system transporting de-oxygenated blood from the heart to the lungs to be re-saturated with oxygen before being dispersed into the systemic circulation.
Diseases:
Thrombus within the pulmonary arteries.
Triad of factors contributing to thrombosis:
- Endothelial injury
- Blood flow stasis
- Hyper-coagulability: Malignancy, thrombophilia, previous VTE, polycythemia
- LMWH (depends on local guidelines as to which one)
- Active bleeding
- Already anticoagulated, e.g. on warfarin
- Compression stockings: TEDS
Presentation:
- SOB
- Haemoptysis
- Pleuritic chest pain
- Well’s score, the most useful way to calculate it:
Investigations & Management:
- Bedside:
- ECG
- Sinus tachycardia
- May have S1Q3T3 (but less common)
- Bloods:
- ABG
- T1RF / Respiratory alkalosis (hyperventilation)
- FBC, U&E, CRP
- Clotting
- Imaging:
- CXR: Likely normal, important to rule out differentials including cancer and pneumonia.
- CT pulmonary angiogram (CTPA)
- VQ scan
- Lower limb duplex scan - DVT (first-line in pregnancy)
- Echocardiogram - If massive PE causing right heart strain
- CT chest with IV contrast that allows us to identify clots within the pulmonary arteries
NICE guidelines (March 2020) recommend:
- Apixaban/rivaroxaban
- Low molecular weight heparin (LMWH) may be used depending on local guidelines
Massive PE causing:
- Haemodynamic instability
- Right heart strain
- Alteplase breaks down fibrin in the clots, rapidly dissolving them. This puts them at increased risk of bleeding elsewhere, e.g. intracranially.
- Warfarin
- 2-3
- DOAC
- LMWH
- Active cancer
- Pregnancy
- Provoked VTE, cause is identifiable.
- Unprovoked VTE due to unknown cause or irreversible cause.
- Active cancer
- Thrombophilia
Increased pressure within the pulmonary arteries.
- Primary pulmonary hypertension / connective tissue disease, e.g. SLE
- Heart failure (left): Poor LV function causes back pressure
- Chronic lung disease, e.g. COPD.
- Pulmonary vascular disease, e.g. PE.
- Sarcoidosis / haematological disorders
- Progressive SOB, fatigue,
- Syncope: Ventricular wall stress can cause vasovagal syncope
- Signs of right heart failure
- ECG: Right axis deviation, RBBB
- CXR: RVH
- Echocardiogram: Look at RV function & estimate pulmonary pressures
- Right heart catheterisation: Diagnostic
- ≥ 25 mmHg
- IV prostanoids, powerful vasodilators acting through prostaglandin system (e.g. epoprostenol).
- Phosphodiesterase-5 inhibitors, prolonging the action of nitrous oxide causing vasodilation (e.g. sildenafil).
- Confusion
- N&V
- Cherry red skin
- ABG: Carboxyhaemoglobin > 20% (diagnostic)
- CXR: ARDS
- 100% O₂
- Hyperbaric (higher pressure than normal) O₂
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