Rapid review: respiratory

• Respiratory emergencies declare themselves early. Tachypnoea, low saturation despite oxygen, altered mentation, silent chest or haemodynamic instability mean stop asking and start doing.
• The same symptoms choose different branches. Fever with cough points to infection, wheeze to airflow obstruction, blood in the sputum to serious bronchi or alveolar disease, pleuritic pain to air or clot in the pleural space, chronic breathlessness to fibrosis.
• A normal chest radiograph never fully clears the airway. Early pneumonia and small pneumothoraces can both hide on the first film.
• Every number below is a starting point. Treat the patient, not the score; confirm the score you use against current local guidance.
• Each short block below gives the presenting picture, the single most likely diagnosis, the best first test, the best first treatment, the commonest wrong answer and the full MedGrasp topic to read next.

By the end of this page you should be able to:

1. Turn a respiratory presenting complaint into the right first diagnosis and investigation.
2. Choose the best first test and the safest first treatment for the major respiratory presentations.
3. Name the commonest trap for each presentation and avoid it.
4. Use the full MedGrasp topic links for detail, doses and follow-up.
5. Recognise when to escalate to acute or specialist care.

This page is a revision sheet for the pulmonology section, written in original wording. It is not a substitute for the full topics listed at the end of each block. Its job is to help you answer a classic exam or clinical stem in the first minute: what is going on here, what do I check first, and what do I do now. More detail, more candidates for each differential and more nuance live on the linked pages, and those pages carry the supporting evidence and fuller reference lists.

Red flags that must change the pace of your assessment include breathlessness at rest, oxygen saturation below about 90 percent on room air, new confusion, a silent chest, hypotension, rapid onset of symptoms, massive haemoptysis, pregnancy, immunosuppression, known lung cancer or a primary pneumothorax in a respiratory compromised patient. ^{[1] [3] [9] [3]}

The most useful initial questions are: how breathless at rest, how long, any fever, sputum (colour and blood), wheeze, pleuritic pain, weight loss, night sweats, chest tightness on exertion, ankle swelling, and sleep disturbance. Each is mechanistic: fever points to infection, exertional dyspnoea out of proportion to exercise to deconditioning or fibrosis, bound to bed to fluid, orthopnoea to pulmonary venous pressure.

Work from the general to the local. General: respiratory rate, saturation on air, temperature, heart rate, blood pressure, mental state, hydration, body habitus. Local: thoracic cage movement and symmetry, trachea position, percussion dullness or hyperresonance, breath sounds and added sounds, accessory muscle use, and neck veins and legs for right heart strain. Measure peak expiratory flow or auscultate for a wheeze on forced expiration when asthma is a possibility. ^{[2] [3]}

• Chest radiograph: the first imaging test for most adults with respiratory symptoms; required when pneumonia, pneumothorax, mass or effusion is suspected. ^[1]
• Pulse oximetry and, when needed, arterial blood gas: essential in dyspnoea and low saturation; take an arterial blood gas when oxygen saturation is 92 percent or less on air. ^{[3] [3]}
• Full blood count, C-reactive protein and basic biochemistry: severity, anaemia and infection markers. ^[1]
• Sputum studies and chest computed tomography: directed, after the clinical picture is clear. ^{[1] [4]}

Presenting picture. An adult, often older, who was well a few days ago, becomes feverish with a productive cough, breathlessness and pleuritic chest pain. The chest may show focal bronchial breath sounds or dullness. A chest radiograph is required to confirm an infiltrate and exclude mimics such as heart failure, embolism and cancer. ^[1]

Single most likely diagnosis. Community-acquired pneumonia, most often pneumococcal, with pathogen mix changing by age, severity and host. ^[1]

Best first test. Chest X-ray, plus pulse oximetry and simple bloods; in severe or resistant-organism risk, take blood and sputum cultures and urinary antigens before the first antibiotic dose if this will not delay treatment. ^[1]

Best first treatment. For low-severity disease, a first-line oral antibiotic, amoxicillin 500 mg three times daily for 5 days, with atypical cover added when indicated by comorbidity; broaden and use intravenous therapy for severe disease, with MRSA and Pseudomonas cover by risk. ^[1]

Commonest wrong answer. Treating a viral tracheobronchitis or an antibiotic-resistant culture as a new bacterial pneumonia, or delaying antibiotics in a patient already showing shock and confusion.

Full topic. infectious-disease/pneumonia

Presenting picture. Episodic wheeze, breathlessness, chest tightness or nocturnal cough with good days and bad days points to asthma. A slowly progressive, exertional dyspnoea with a chronic productive cough in an adult with a smoking or biomass exposure history points to chronic obstructive pulmonary disease. Both can wheeze; the time course and exposure separate them. ^{[2] [3]}

Single most likely diagnosis. Asthma in the young or atopic patient with variable obstruction; COPD in the older, exposed patient with largely fixed obstruction. ^{[2] [3]}

Best first test. For asthma, document variable airflow limitation, ideally spirometry showing an FEV1 (forced expiratory volume in one second) increase of 12 percent or more and 200 mL or more after a bronchodilator. ^[2] For COPD, confirm persistent airflow obstruction on post-bronchodilator spirometry. ^[3]

Best first treatment. Asthma: an inhaled corticosteroid containing regimen, preferably low-dose inhaled corticosteroid-formoterol taken as needed for symptom relief in people aged 12 and over, rather than a short-acting beta-agonist alone. ^[2] COPD: short-acting and long-acting bronchodilators as the maintenance core, with inhaled corticosteroid added when eosinophils are raised or exacerbations persist. ^[3]

Commonest wrong answer. Settling for a short-acting beta-agonist inhaler alone in asthma because the patient feels well; this pattern carries the highest avoidable death risk. ^[2]

Full topics. pulmonology/asthma, pulmonology/copd

Presenting picture. Visible blood mixed with sputum from the lower airways. The volume matters far less than the cause in a medical student's first assessment: even small amounts in a smoker, tuberculosis-exposed patient or immunosuppressed patient demand a diagnosis. Distinguish blood that originates from the upper airway or vomited stomach by history, colour and effort. ^{[4] [7]}

Single most likely diagnosis. In a smoker over 40, lung cancer until proven otherwise; in tuberculosis-endemic settings and young patients, pulmonary tuberculosis; in children and young adults with recurrent bleeding, bronchiectasis. ^{[4] [7]}

Best first test. An urgent chest radiograph in adults aged 40 and over with unexplained symptoms, followed by chest computed tomography; further branching and sputum testing is directed by the clinical picture and local pathway. ^[7]

Best first treatment. Secure the airway, assess haemodynamic state, stop any anticoagulation that is unsafe, and treat the underlying cause: infection or tuberculosis when proven, malignancy by the cancer pathway. Massive bleeding should be referred immediately for bronchoscopic or radiological control. ^[7]

Commonest wrong answer. Reassuring a patient after a normal chest radiograph; a plain film misses central lesions, non-massive bleeds and the early peripheral tumour.

Full topics. pulmonology/chronic-cough-and-haemoptysis, pulmonology/pulmonary-vasculitis-and-alveolar-haemorrhage, infectious-disease/tuberculosis

Presenting picture. Sharp pain worse on inspiration, often with breathlessness. In a tall, young smoker with sudden onset, think pneumothorax; in a patient with risk factors for thrombosis and tachypnoea out of proportion to pain, think pulmonary embolism. Both can have a normal chest radiograph early on. ^{[5] [9]}

Single most likely diagnosis. Primary spontaneous pneumothorax in the young, thin smoker; secondary pneumothorax in older patients with underlying lung disease. ^[9]

Best first test. Chest radiograph, with expiratory views or computed tomography when the film is equivocal. ^[9]

Best first treatment. Observation without intervention for an asymptomatic or minimally symptomatic pneumothorax; needle aspiration or chest drain for symptomatic or high-risk pneumothorax. ^[9]

Commonest wrong answer. Jumping straight to a chest drain for a small, well-tolerated primary pneumothorax that needs observation.

Single most likely diagnosis. Deep-vein thrombosis with venous thromboembolism, usually with pleuritic pain, breathlessness and tachycardia. ^[5]

Best first test. Plasma D-dimer when the pre-test probability is not high, followed by an immediate computed tomography pulmonary angiogram if that probability is intermediate or high, or if D-dimer is raised. ^[5]

Best first treatment. Anticoagulation, started as interim therapeutic anticoagulation when the diagnosis is still being confirmed and continued for confirmed venous thromboembolism. ^[5]

Commonest wrong answer. Anchoring on a normal chest radiograph or a negative early electrocardiograph to exclude embolism; neither test rules it out.

Full topics. pulmonology/pneumothorax, pulmonology/pulmonary-embolism

Presenting picture. Progressive exertional dyspnoea over months, a dry cough, fine late inspiratory crackles at the bases, and clubbing with restrictive physiology on spirometry. Fibrotic interstitial disease is the pattern; drug-induced, occupational, connective-tissue and hypersensitivity pneumonitis causes need specific exclusion. ^[6]

Single most likely diagnosis. Idiopathic pulmonary fibrosis in an older patient with the usual interstitial pneumonia pattern; secondary interstitial lung disease when an exposure or connective tissue disease is present. ^[6]

Best first test. Chest computed tomography with high-resolution images. ^[6]

Best first treatment. Refer to a respiratory or interstitial lung disease service for multidisciplinary review; antifibrotic therapy (for example, nintedanib) when assessment confirms idiopathic pulmonary fibrosis meeting funded criteria. ^[6]

Commonest wrong answer. Calling the crackles "just a bit of heart failure" and missing the progressive fibrosis that only becomes irreversible later.

Full topics. pulmonology/interstitial-lung-disease, pulmonology/hypersensitivity-pneumonitis, pulmonology/pneumoconioses

Presenting picture. An asymptomatic adult in whom a rounded opacity is found on imaging done for another reason. Risk is set by size, margin, density (solid, subsolid, ground-glass) and growth on serial imaging; nothing is decided on one appearance alone. ^[7]

Single most likely diagnosis. A benign granuloma or hamartoma for small, stable, smooth, calcified nodules; a primary bronchial carcinoma if the nodule has grown, is spiculated, has enlarged or has rounded lymph nodes. ^[7]

Best first test. Chest radiograph for symptomatic suspected cancer in adults aged 40 and over, then chest computed tomography with thin slices and volumetric assessment for the nodule itself. ^[7]

Best first treatment. Surveillance with interval imaging for low-risk nodules; biopsy or resection according to risk, never an urgent clinic appointment substitute for the cancer pathway. ^[7]

Commonest wrong answer. Treating size as the only risk factor; a margins assessment and comparison with old images often matters more than a single measurement.

Full topics. pulmonology/solitary-pulmonary-nodule, pulmonology/lung-cancer

Presenting picture. Loud snoring, witnessed apnoeas, restless sleep and daytime somnolence in an overweight adult, or a syncopal or breathless older patient. Hypertension, atrial fibrillation, nocturia and a large neck are supporting clues. ^[10]

Single most likely diagnosis. Obstructive sleep apnoea-hypopnoea syndrome, with central sleep apnoea in sedated, opioid-exposed or heart failure patients. ^[10]

Best first test. Home respiratory polygraphy, with polysomnography or oximetry as alternatives when the first-choice test is unavailable or results do not match significant symptoms. ^[10]

Best first treatment. In mild disease with symptoms affecting quality of life, offer fixed-level continuous positive airway pressure; for moderate or severe symptomatic disease continuous positive airway pressure is a standard treatment option. Weight loss, alcohol reduction and positional advice support all grades. ^[10]

Commonest wrong answer. Dismissing the patient as "just sleepy" or "overweight"; untreated sleep apnoea damages driving safety, blood pressure and cardiovascular risk long before symptoms feel severe.

Full topics. pulmonology/sleep-apnoea-and-obesity-hypoventilation

Presenting picture. A subacute or chronic cough with weight loss, fever, night sweats and sometimes haemoptysis, often with mediastinal nodes or upper-lobe infiltrates. Symptoms overlap with cancer, sarcoid and pneumonia, so tuberculosis remains a diagnosis to make active, not a label to give casually. ^[4]

Single most likely diagnosis. Pulmonary tuberculosis, with higher suspicion in contacts, immigrants from endemic regions, immunosuppressed patients and health care workers. ^[4]

Best first test. Chest radiograph and three deep-cough sputum samples, preferably including one early morning specimen, for microscopy and culture, plus nucleic acid amplification testing for the Mycobacterium tuberculosis complex and rifampicin resistance by risk assessment. ^[4]

Best first treatment. For drug-susceptible disease, a standard regimen of isoniazid, rifampicin, pyrazinamide and ethambutol for 2 months, followed by isoniazid and rifampicin for a further 4 months, with specialist supervision and direct observation where adherence is doubtful. ^[4]

Commonest wrong answer. Waiting for culture before starting treatment in a highly probable smear-positive, drug-susceptible case, or giving a broad-spectrum antibiotic "just in case" and obscuring the clinical picture.

Full topics. infectious-disease/tuberculosis

Presenting picture. A young or middle-aged adult with cough, dyspnoea and constitutional symptoms such as fever, fatigue or erythema nodosum, with bilateral hilar lymphadenopathy on chest imaging. Cardiac, ocular and neurological sarcoid can present with nothing in the chest at all. ^[8]

Single most likely diagnosis. Sarcoidosis in the classic radiographic stages; other granulomatous diseases need exclusion before the label is fixed. ^[8]

Best first test. Imaging supports the diagnosis, usually chest radiography with high-resolution computed tomography when mediastinal lymph nodes or parenchymal disease need characterisation; tissue confirmation is used when the picture is atypical. ^[8]

Best first treatment. Observation for asymptomatic, mild or self-limiting disease; corticosteroids as first-line therapy for patients requiring treatment, with screening for latent tuberculosis and hepatitis before immunosuppression. ^[8]

Commonest wrong answer. Treating every radiographic finding; many asymptomatic stage 1 disease resolve without therapy and steroids carry their own long-term burden.

Full topics. pulmonology/sarcoidosis

Presenting picture. Breathlessness with confusion, somnolence, cyanosis or fatigue in the setting of chronic lung disease or an acute illness. Type 1 failure is low oxygen with normal or low carbon dioxide; type 2 failure is high carbon dioxide. Arterial blood gas is what separates them. ^[3]

Single most likely diagnosis. Exacerbation of chronic obstructive pulmonary disease leading to type 2 (hypercapnic) failure; pneumonia or acute respiratory distress syndrome leading to type 1 (hypoxaemic) failure. ^{[1] [3] [3]}

Best first test. Arterial blood gas, together with pulse oximetry and chest radiograph. ^{[3] [3]}

Best first treatment. Controlled, titrated oxygen to a saturation target appropriate to the patient, choosing a lower target when carbon dioxide retention is a risk, treating the precipitant airway disease, sepsis or fluid overload, and escalating to non-invasive ventilation if type 2 (hypercapnic) failure persists despite medical therapy. ^[3]

Commonest wrong answer. Giving high-flow uncontrolled oxygen to a carbon dioxide retainer and converting compensated type 2 failure into a respiratory acidosis. ^[3]

Full topics. pulmonology/hypoxaemia-and-respiratory-failure, pulmonology/ards, pulmonology/oxygen-and-mechanical-ventilation

• Red flags first: breathlessness at rest, saturation below about 90 percent on air, confusion, silent chest, hypotension, pregnancy, immunosuppression and massive haemoptysis demand immediate stabilisation.
• Community-acquired pneumonia is the working diagnosis for fever with productive cough and focal signs; a chest radiograph is essential and severity directs treatment.
• Asthma needs objective evidence of variable obstruction and an inhaled corticosteroid containing regimen; COPD needs obstructive post-bronchodilator spirometry and bronchodilation.
• Haemoptysis in a smoker over 40 is a cancer pathway until a careful assessment proves otherwise; a normal chest film does not clear it.
• Pleuritic pain is split by history into air leak (pneumothorax) and embolic (pulmonary embolism); both can have a normal first film.
• Interstitial lung disease is diagnosed by high-resolution chest computed tomography and needs specialist multidisciplinary review.
• A suspected lung nodule is risk-stratified by size, margin, density and growth, never by one measurement alone.
• Sleep apnoea is tested with home respiratory polygraphy and treated with continuous positive airway pressure when symptomatic.
• Tuberculosis needs three deep-cough sputum samples and nucleic acid amplification testing, with treatment only after the diagnosis is thought likely.
• Sarcoidosis observation is reasonable for asymptomatic disease; steroids are first-line when treatment is needed. ^[8]
• Respiratory failure decisions require an arterial blood gas; oxygen must be titrated, especially where carbon dioxide retention is a risk.
• Clinical assessment comes before any score; scores are only memory aids, not verdicts.

• infectious-disease/pneumonia
• pulmonology/asthma
• pulmonology/copd
• pulmonology/chronic-cough-and-haemoptysis
• pulmonology/pulmonary-vasculitis-and-alveolar-haemorrhage
• pulmonology/pneumothorax
• pulmonology/pulmonary-embolism
• pulmonology/interstitial-lung-disease
• pulmonology/hypersensitivity-pneumonitis
• pulmonology/pneumoconioses
• pulmonology/solitary-pulmonary-nodule
• pulmonology/lung-cancer
• pulmonology/sleep-apnoea-and-obesity-hypoventilation
• infectious-disease/tuberculosis
• pulmonology/sarcoidosis
• pulmonology/hypoxaemia-and-respiratory-failure
• pulmonology/ards
• pulmonology/oxygen-and-mechanical-ventilation