🚨 Respiratory emergencies can deteriorate rapidly through hypoxaemia, hypercapnia, airway obstruction, shock, respiratory arrest or cardiac arrest. The safest first step is ABCDE assessment, high-flow oxygen if critically unwell, early senior help, blood gas where indicated, chest imaging, and rapid treatment of reversible causes. In patients at risk of hypercapnic respiratory failure, especially COPD, use controlled oxygen with a usual target saturation of 88–92% unless advised otherwise.

🚩 Respiratory Red Flags

🫁 Severe breathlessness, exhaustion, silent chest or inability to speak full sentences.
🧠 Confusion, agitation, drowsiness or reduced conscious level.
🟦 Cyanosis or SpO₂ persistently low despite oxygen.
📉 Hypotension, shock, arrhythmia or cardiac arrest.
📈 Rising PaCO₂, respiratory acidosis or deteriorating blood gas.
🩸 Haemoptysis, pleuritic chest pain or suspected pulmonary embolism.
🫀 Chest pain with ECG changes or concern for ACS.
🦠 Fever, sepsis, pneumonia or immunosuppression.
🫁 Stridor, drooling, choking or suspected upper airway obstruction.

🚑 Immediate Generic Approach

🔄 Use an ABCDE approach and call for senior/critical care help if unstable.
🫁 Give oxygen immediately if hypoxaemic, shocked, peri-arrest or critically unwell.
🎯 Oxygen targets: usually 94–98%; use 88–92% if at risk of hypercapnic respiratory failure.
🧪 Check ABG/VBG if severe breathlessness, low oxygen, suspected CO₂ retention, shock, sepsis or NIV consideration.
🩻 Chest X-ray if pneumonia, pneumothorax, pulmonary oedema, COPD exacerbation complication or unclear diagnosis.
💉 Bloods: FBC, U&E, CRP, LFTs, troponin/BNP/D-dimer where appropriate, blood cultures if sepsis.
🫀 ECG for chest pain, PE, arrhythmia, hyperkalaemia or cardiac cause of breathlessness.
🚫 Avoid sedatives/opioids unless clearly indicated and monitored, as they may worsen respiratory failure.

📊 Respiratory Emergencies

Respiratory Emergency	Clinical Presentation	Investigations	Immediate Management
🌬 Acute Asthma Exacerbation	Wheeze, breathlessness, cough and chest tightness. Accessory muscle use, tachypnoea, tachycardia. Unable to complete sentences if severe. Life-threatening signs: silent chest, cyanosis, exhaustion, confusion, hypotension, SpO₂ <92%, normal/rising PaCO₂.	PEF compared with best/predicted if able. Oxygen saturation. ABG if SpO₂ <92%, life-threatening features or poor response. CXR only if pneumothorax, consolidation or other complication suspected.	Oxygen to target 94–98%. High-dose inhaled salbutamol via oxygen-driven nebuliser or MDI/spacer. Add nebulised ipratropium in severe/life-threatening asthma. Prednisolone 40–50 mg orally or IV hydrocortisone if unable to take oral. Consider IV magnesium sulfate for acute severe/life-threatening asthma with poor response. No sedatives. Escalate early to ICU if tiring, rising CO₂ or poor response.
🫧 Pneumothorax	Sudden unilateral pleuritic chest pain and breathlessness. Reduced breath sounds and hyper-resonance on affected side. Tension pneumothorax: severe respiratory distress, hypotension, distended neck veins, tracheal deviation late.	Clinical diagnosis for tension pneumothorax - do not wait for X-ray. CXR for stable suspected pneumothorax. Bedside ultrasound may help in trauma/critical care. CT if uncertain or complex secondary pneumothorax.	Tension pneumothorax: immediate decompression followed by definitive chest drain. Small stable pneumothorax may be observed depending on size, symptoms and local BTS pathway. Symptomatic, large or secondary pneumothorax often needs aspiration or chest drain. Give oxygen if hypoxaemic and arrange respiratory/surgical follow-up.
🩸 Pulmonary Embolism	Sudden breathlessness, pleuritic chest pain, haemoptysis or syncope. Tachycardia, tachypnoea, hypoxia. May have DVT symptoms: unilateral leg swelling/pain. Massive PE: hypotension, shock, collapse or cardiac arrest.	Use Wells score / clinical probability assessment. D-dimer if low probability and suitable. CTPA first-line imaging for many patients. V/Q scan if CTPA unsuitable, e.g. pregnancy/contrast issues depending on pathway. ECG may show sinus tachycardia or right heart strain; S1Q3T3 is uncommon.	Immediate admission if haemodynamically unstable. Start anticoagulation if PE likely and bleeding risk acceptable while awaiting imaging, according to local policy. LMWH, DOAC or unfractionated heparin depending on context, renal function and instability. Thrombolysis for massive/high-risk PE with haemodynamic instability if no contraindication. Consider embolectomy/catheter therapy if thrombolysis contraindicated or fails.
🫁 Acute Respiratory Distress Syndrome	Severe hypoxaemia and respiratory distress. Often follows sepsis, severe pneumonia, aspiration, pancreatitis, trauma or transfusion. Bilateral infiltrates not fully explained by cardiac failure/fluid overload. Oxygen requirement escalates rapidly.	ABG: severe hypoxaemia; PaO₂/FiO₂ ratio used in ICU classification. CXR/CT: bilateral infiltrates. Sepsis screen and cultures where infection suspected. Echo/BNP if cardiogenic pulmonary oedema is a differential.	Critical care management. Treat underlying cause, e.g. antibiotics/source control in sepsis. Lung-protective ventilation with low tidal volumes and appropriate PEEP. Prone positioning in severe ARDS. Conservative fluid strategy once shock corrected; consider neuromuscular blockade/ECMO in selected severe cases.
🫁 Acute COPD Exacerbation	Worsening breathlessness, cough, wheeze or sputum volume/purulence. Accessory muscle use and prolonged expiration. Confusion, drowsiness or cyanosis suggests respiratory failure. May be triggered by infection, pollution, PE, pneumothorax or heart failure.	Oxygen saturation and ABG if hypoxaemic, severe or drowsy. CXR to exclude pneumonia, pneumothorax or heart failure. FBC, U&E, CRP; sputum culture if severe or not responding. ECG if chest pain, arrhythmia or cardiac cause suspected.	Controlled oxygen target usually 88–92%. Nebulised salbutamol and ipratropium, air-driven if CO₂ retention risk with oxygen titrated separately. Oral prednisolone, commonly 30 mg daily for 5 days, according to local/NICE guidance. Antibiotics if increased sputum purulence or clinical bacterial infection. NIV if persistent respiratory acidosis despite optimal medical therapy. Escalate if worsening acidosis, exhaustion, reduced consciousness or NIV failure.
🫁 Anaphylaxis with Respiratory Compromise	Rapid onset airway/breathing/circulation problems after trigger. Wheeze, stridor, throat tightness, tongue/lip swelling. Urticaria, flushing, angioedema may occur but can be absent. Hypotension, collapse, abdominal pain or vomiting may occur.	Clinical diagnosis - do not delay treatment. Monitor SpO₂, BP, ECG and respiratory status. Serum tryptase can support later diagnosis but is not needed acutely.	IM adrenaline immediately into anterolateral thigh; repeat if needed. Call for help, lie patient flat with legs raised unless breathing prevents this. High-flow oxygen and IV fluids for hypotension. Bronchodilator for persistent wheeze after adrenaline. Antihistamines may treat skin symptoms but are not first-line life-saving treatment. Routine corticosteroids are no longer recommended for initial emergency treatment.
🍇 Foreign Body Aspiration / Choking	Sudden choking, coughing, gagging or stridor. Unable to speak/cough effectively in complete obstruction. Unilateral wheeze or reduced breath sounds if lodged bronchial foreign body. Children, older adults and neurological dysphagia are high-risk groups.	Clinical diagnosis in acute choking. CXR if stable; may show air trapping or atelectasis. Bronchoscopy is diagnostic and therapeutic.	Follow choking algorithm: encourage cough if effective; back blows/abdominal thrusts if ineffective cough in adults/children. Start CPR if unconscious. Urgent rigid bronchoscopy for persistent suspected airway foreign body. Oxygen and monitor for pneumonia, pneumothorax or airway oedema.
🔥 Carbon Monoxide Poisoning	Headache, dizziness, nausea, weakness, confusion. Collapse, seizures, chest pain or coma in severe cases. Multiple people/pets affected suggests environmental exposure. Pulse oximetry may be falsely normal.	Carboxyhaemoglobin level by co-oximetry. ABG/VBG with lactate and pH. ECG and troponin if chest pain, older, pregnant or severe poisoning. Pregnancy test where relevant.	Remove from exposure and give 100% oxygen immediately. Discuss severe cases with TOXBASE/NPIS. Consider hyperbaric oxygen in selected severe poisoning, pregnancy, neurological features or cardiac involvement according to local/toxicology advice. Advise environmental safety check before returning home.
🫁 Acute Epiglottitis / Supraglottitis	Severe sore throat, dysphagia, drooling, muffled voice. Stridor, respiratory distress or sitting forward. High fever may occur. Can occur in adults as well as children.	Clinical diagnosis; avoid distressing the patient. Flexible nasendoscopy only by experienced clinician in controlled setting. Do not force throat examination if unstable. Bloods/cultures after airway plan if safe.	Airway emergency: call ENT, anaesthetics and ICU early. Keep patient calm, upright and oxygenated. Prepare for controlled intubation or surgical airway if needed. IV antibiotics after airway safety addressed. ICU/HDU monitoring.
🦠 Severe Pneumonia / Sepsis	Fever, cough, sputum, pleuritic pain and breathlessness. Confusion, hypotension, hypoxia or high respiratory rate suggests severe disease. May present atypically in frailty or older adults.	CXR, oxygen saturations, blood cultures if severe/sepsis. FBC, U&E, CRP, LFTs, lactate, ABG/VBG if severe. Sputum culture if productive/severe; viral testing depending on season/pathway. Severity scores such as CURB-65 can support decision-making.	Oxygen to target saturation. Sepsis pathway if sepsis suspected. Prompt antibiotics according to local community/hospital-acquired pneumonia guidance. IV fluids if shocked; cautious if heart failure/renal disease. Escalate to ICU for severe hypoxaemia, shock or respiratory failure.
🌊 Acute Pulmonary Oedema	Severe breathlessness, orthopnoea and pink frothy sputum. Crackles, hypoxia, hypertension or hypotension. Often due to acute heart failure, ACS, arrhythmia or fluid overload.	CXR: pulmonary oedema. ECG and troponin if ACS suspected. BNP/NT-proBNP can support heart failure diagnosis. ABG/VBG if severe; U&E before/after diuresis.	Sit upright, oxygen if hypoxaemic. CPAP/NIV if severe respiratory distress or hypoxaemia. IV nitrates if hypertensive and no contraindication. IV diuretics if fluid overload. Treat trigger: ACS, arrhythmia, hypertensive emergency, valve disease or renal failure.

📊 Quick Pattern Recognition

Presentation	Think Of	Immediate Action
Silent chest, exhaustion, normal/rising CO₂	Life-threatening asthma	O₂, salbutamol/ipratropium, steroids, MgSO₄, ICU early.
COPD + drowsy + low pH/high CO₂	Hypercapnic respiratory failure	Controlled O₂ 88–92%, bronchodilators, steroids, NIV if acidotic.
Sudden pleuritic pain + unilateral reduced breath sounds	Pneumothorax	CXR if stable; decompress immediately if tension.
Chest pain + dyspnoea + tachycardia + DVT risk	Pulmonary embolism	Wells/D-dimer/CTPA pathway; anticoagulate if likely.
Rapid airway swelling/wheeze/hypotension after trigger	Anaphylaxis	IM adrenaline first.
Headache/confusion + multiple household members unwell	Carbon monoxide poisoning	100% oxygen, carboxyhaemoglobin, toxicology advice.
Drooling + stridor + severe sore throat	Epiglottitis	Airway team: ENT/anaesthetics/ICU.

🚫 Common Pitfalls

❌ Assuming a wheezy COPD patient should receive no oxygen - give controlled oxygen and monitor gases.
❌ Being reassured by a normal PaCO₂ in severe asthma - this can be a pre-arrest sign.
❌ Waiting for CXR in suspected tension pneumothorax.
❌ Using antihistamines or steroids before adrenaline in anaphylaxis.
❌ Trusting pulse oximetry in carbon monoxide poisoning.
❌ Forgetting PE in unexplained hypoxia, syncope or pleuritic chest pain.
❌ Distressing a patient with suspected epiglottitis by unnecessary throat examination.

📝 Exam Pearls

🌬 Asthma: silent chest and rising CO₂ are ominous.
🫁 COPD: target SpO₂ 88–92% if at risk of CO₂ retention.
🫧 Tension pneumothorax is a clinical diagnosis - decompress immediately.
🩸 Massive PE causes shock and may need thrombolysis.
🫁 Anaphylaxis: IM adrenaline is first-line; steroids are not routine first-line emergency treatment.
🔥 CO poisoning: pulse oximetry can look normal; use co-oximetry.
🫁 Epiglottitis: airway first, investigations later.

🧠 Teaching Note

Respiratory emergencies are best approached by asking: is air getting in, is oxygen crossing the lung, is blood reaching the lung, and is ventilation removing CO₂? Asthma and COPD are mainly airflow problems, PE is a perfusion problem, pneumothorax is a mechanical lung expansion problem, and ARDS/pneumonia are gas-exchange problems. Blood gases are useful because they tell you when compensation is failing: hypoxaemia shows oxygenation failure, while rising CO₂ and acidosis show ventilatory failure. That is why the same core actions recur: oxygen to target, bronchodilate when appropriate, treat the cause, monitor gases, and escalate early when the patient is tiring.

📚 References & UK Resources

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Respiratory Emergencies: Revision ✅