How to manage a patient with sudden onset breathing difficulty in the emergency department, potentially with a history of respiratory or cardiac disease, such as Chronic Obstructive Pulmonary Disease (COPD) or asthma?

Emergency Department Approach to Sudden Onset Breathing Difficulty

Immediately assess the patient using the ABCDE (Airway, Breathing, Circulation, Disability, Exposure) approach, measure oxygen saturation as the "fifth vital sign," and initiate oxygen therapy targeting 94-98% for most patients or 88-92% for those at risk of hypercapnic respiratory failure while simultaneously determining if the patient is in respiratory or cardiac arrest. 1, 2, 3

Immediate Life-Threatening Assessment (First 60 Seconds)

Is This Cardiac or Respiratory Arrest?

• Check responsiveness and breathing pattern immediately - if the patient is unresponsive with gasping or absent breathing, assume cardiac arrest and begin CPR without delay 1, 4
• Agonal gasping occurs in 40-60% of cardiac arrests and is the most commonly misinterpreted sign - do not mistake gasping for adequate breathing 4
• Check for a pulse for no more than 10 seconds; if no definite pulse is felt, begin chest compressions immediately 1, 4
• If pulse is present but patient has gasping or no normal breathing (respiratory arrest), provide rescue breathing or bag-mask ventilation until spontaneous breathing returns 1

Critical Positioning

• Allow fully conscious hypoxaemic patients to maintain the most upright posture possible unless there is evidence of trauma requiring spinal immobilization 1
• If the patient shows evidence of shock and is responsive with normal breathing, place them in a supine position 1
• Do not move patients with suspected neck, back, hip, or pelvic injury unless their position is blocking the airway or the area is unsafe 1

Vital Signs and Oxygen Therapy (First 2-5 Minutes)

Measure All Vital Signs Immediately

• Record respiratory rate, pulse rate, blood pressure, temperature, and oxygen saturation - these are essential for all acutely breathless patients 1, 2
• Use a physiological "track and trigger" system such as the National Early Warning Score (NEWS) to guide escalation decisions 1, 2
• Record the inspired oxygen device and flow rate on the observation chart alongside the oximetry result 1, 2

Oxygen Therapy Algorithm

For patients WITHOUT risk of hypercapnic respiratory failure:

• Target oxygen saturation: 94-98% 1, 2
• If SpO2 <94%, commence oxygen via nasal cannula or simple face mask and titrate to target 1
• If critically ill, start with 15 L/min via reservoir mask 1

For patients AT RISK of hypercapnic respiratory failure:

• Target oxygen saturation: 88-92% (or level stated on patient's oxygen alert card) 1, 2
• Start with 24% or 28% Venturi mask or 1-2 L/min nasal oxygen 1, 4
• Obtain arterial blood gas urgently 1
• High-concentration oxygen in these patients causes worsening hypercapnic respiratory failure and respiratory acidosis 1, 2

Patients at Risk of Hypercapnic Respiratory Failure

Assume risk if the patient has: 1, 2, 4

• COPD (especially moderate-severe, previous respiratory failure, or on long-term oxygen therapy)
• Age >50 years who are long-term smokers with chronic breathlessness on minor exertion
• Severe chest wall or spinal disease (kyphoscoliosis, ankylosing spondylitis)
• Neuromuscular disorders (especially if wheelchair-bound)
• Morbid obesity (BMI >40 kg/m²)
• Bronchiectasis with fixed airflow obstruction
• Cystic fibrosis
• Home mechanical ventilation
• Opioid, benzodiazepine, or other respiratory depressant overdose

Condition-Specific Emergency Management (First 5-10 Minutes)

Asthma or COPD with Wheezing

• Administer nebulized bronchodilators immediately - albuterol (salbutamol) 2.5-5 mg via oxygen-driven nebulizer at 6-8 L/min 1, 5
• For patients at risk of hypercapnic respiratory failure, use compressed air to drive nebulizers with nasal oxygen at 2 L/min; if compressed air unavailable, limit oxygen-driven nebulizers to 6 minutes 1
• If poor response to initial treatment, repeat albuterol with addition of ipratropium (Atrovent) 0.5 mg 1
• First aid providers should assist patients with their prescribed bronchodilator devices 1
• Any patient remaining ill despite intensive treatment requires chest radiograph to exclude pneumothorax 1

Suspected Anaphylaxis

• If respiratory difficulty occurs with cutaneous manifestations (hives, lip/eye swelling) or cardiovascular effects (hypotension, shock), this represents anaphylaxis involving two or more body systems 1, 2
• Administer epinephrine 0.3 mg intramuscularly immediately for adults and children >30 kg (0.15 mg for children 15-30 kg) 1
• Call for emergency assistance immediately when caring for suspected anaphylaxis 1
• When patient does not respond to initial dose and advanced care is delayed, a second dose may be considered 1

Suspected Opioid Overdose

• For patients with suspected opioid overdose who have a definite pulse but no normal breathing or only gasping, administer naloxone in addition to providing rescue breathing 1, 4
• Standard resuscitative measures (high-quality CPR with compressions plus ventilation) take priority over naloxone administration if cardiac arrest is present 1
• Do not delay activating emergency response systems while awaiting response to naloxone 1
• After return of spontaneous breathing, observe patient in healthcare setting until risk of recurrent opioid toxicity is low 1

Suspected Cardiac Cause (Chest Pain, Orthopnea, Peripheral Edema)

• Call for emergency assistance immediately rather than attempting transport 1, 2
• If signs suggest myocardial infarction and patient has no allergy or contraindication (such as recent bleeding), encourage patient to take aspirin while waiting for advanced care 1
• Aspirin significantly decreases mortality in myocardial infarction 1
• Do not encourage aspirin if chest pain does not suggest cardiac origin or if uncertain 1

Ventilation Considerations for Severe Asthma

Avoiding Complications in Mechanically Ventilated Asthma Patients

• Use lower tidal volumes, lower respiratory rate, and increased expiratory time to minimize auto-PEEP and barotrauma 1
• High tidal volumes at higher respiratory rates lead to progressive air trapping and decreased effective ventilation 1
• Evaluate for tension pneumothorax if sudden difficulty ventilating, high airway pressures, or sudden blood pressure decrease occurs 1
• Brief disconnection from ventilator or pause in bag-mask ventilation with thoracic compression may relieve life-threatening hyperinflation 1

Blood Gas Interpretation and Oxygen Adjustment

For Patients at Risk of Hypercapnic Respiratory Failure

• If arterial blood gas shows pH <7.25 or respiratory acidosis with PO2 >10 kPa (75 mmHg), the patient likely has excessive oxygen therapy 1
• Do not discontinue oxygen immediately - oxygen level falls in 1-2 minutes while carbon dioxide takes much longer to correct 1
• Step down oxygen to 28% or 35% Venturi mask, or 1-2 L/min nasal cannula, maintaining saturation target of 88-92% 1
• 30% of COPD patients receive excessive oxygen (>35%) in ambulances, and 35% still receive high-concentration oxygen when blood gases are taken in hospital 1

Escalation Criteria

When to Call for Intensive Care or Resuscitation Team

• Patient cannot maintain target oxygen saturations despite oxygen therapy 1, 2
• Signs of impending respiratory failure: altered mental status, inability to speak in full sentences, accessory muscle use 2
• Patient triggers high-risk criteria on NEWS or similar scoring system 1, 2
• Worsening respiratory acidosis despite controlled oxygen therapy 1
• Need for advanced airway management or mechanical ventilation 3, 6

Common Pitfalls to Avoid

• Mistaking agonal gasps for adequate breathing - this is the most common error leading to delayed CPR and decreased survival 4
• Administering high-concentration oxygen to COPD patients or others at risk of hypercapnic respiratory failure 1, 2
• Prolonged pulse checks (>10 seconds) that delay chest compressions 4
• Failing to recognize that elderly patients may present with confusion, delirium, or falls rather than classic breathlessness 2
• Overlooking cardiac causes in women who may present with atypical symptoms 2
• Assuming normal pulse oximetry rules out serious pathology (falsely normal in carbon monoxide poisoning) 2
• Delaying assessment when oxygen saturation drops suddenly by 3% 2