Respiratory Emergencies: Revision✅

🚨 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

📊 Quick Pattern Recognition

🚫 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

• NICE CKS – Acute asthma exacerbation
• BNF/NICE – Acute asthma treatment summary
• NICE CKS – COPD
• NICE NG158 – Venous thromboembolic diseases
• NICE CKS – Pulmonary embolism
• Resuscitation Council UK – Anaphylaxis guidance
• TOXBASE – UK poisons information