How do I order oxygen therapy for a patient with potential respiratory distress, considering their oxygen saturation level and medical history, including conditions like COPD?

How to Order Oxygen Therapy

For most acutely breathless patients, start oxygen immediately to achieve target saturations of 94-98%, or 88-92% if the patient has COPD or other risk factors for hypercapnic respiratory failure. 1

Initial Assessment (ABC Approach)

Perform immediate clinical assessment including: 1

• Airway patency - ensure airway is clear before oxygen administration 1
• Breathing - measure respiratory rate (normal <20 breaths/min) 1
• Circulation - record pulse rate and blood pressure 1
• Pulse oximetry - measure SpO2 immediately in all breathless patients 1

Determine Target Oxygen Saturation

Standard Target: 94-98% 1, 2

Use for patients with:

• Pneumonia without COPD 2
• Heart failure without COPD 3
• Acute coronary syndromes 1
• Stroke 1
• Most poisonings 1

Lower Target: 88-92% 1, 4

Use for patients with risk factors for hypercapnic respiratory failure:

• Known COPD (most important) 1
• Morbid obesity 1
• Cystic fibrosis 1
• Chest wall deformities 1
• Neuromuscular disorders 1
• Bronchiectasis with fixed airflow obstruction 1

Critical caveat: Even in COPD patients with normal PCO2, maintain the 88-92% target initially until blood gases confirm normocapnia, then you may adjust to 94-98%. 1 However, recent evidence shows that maintaining 88-92% targets for all COPD patients (regardless of CO2 levels) results in lowest mortality. 4

Select Initial Oxygen Delivery Device

For Severe Hypoxemia (SpO2 <85%) 2

• Reservoir mask (non-rebreather) at 15 L/min 2
• This rapidly corrects life-threatening hypoxemia 2

For Moderate Hypoxemia (SpO2 85-93%) 2

• Nasal cannulae at 2-6 L/min, OR 1, 2
• Simple face mask at 5-10 L/min 1, 2

For COPD or Risk of Hypercapnia (Target 88-92%) 1

Start with controlled low-concentration oxygen:

• 24% Venturi mask at 2-3 L/min (preferred), OR 1
• 28% Venturi mask at 4 L/min, OR 1
• Nasal cannulae at 1-2 L/min if Venturi masks unavailable 1

Important adjustment: If respiratory rate >30 breaths/min, increase Venturi mask flow by up to 50% to meet inspiratory flow demands. 1, 2

Titration Protocol

• Allow at least 5 minutes at each oxygen dose before adjusting 2, 3
• Adjust oxygen concentration upward if SpO2 remains below target 1
• Reduce oxygen concentration if SpO2 exceeds target range 1
• If target not achieved with nasal cannulae or simple mask, escalate to reservoir mask and seek senior help 2

Monitoring Requirements

Continuous Monitoring Until Stable 1

• Pulse oximetry (continuous initially) 1
• Respiratory rate 1
• Heart rate 1

At Least Twice Daily Once Stable 2, 3

• Oxygen saturation 2
• Respiratory rate 2
• Heart rate 2
• Blood pressure 2
• Mental status 2

Warning sign: Respiratory rate >30 breaths/min indicates respiratory distress requiring immediate intervention, even if SpO2 appears adequate. 2

Obtain Arterial Blood Gases When 1, 2

• Critically ill patients or shock (systolic BP <90 mmHg) - use arterial sample 1
• Any patient at risk of hypercapnia receiving oxygen 1
• Unexpected fall in SpO2 below 94% 2
• Requiring increased FiO2 to maintain constant saturation 2
• Respiratory rate >30 breaths/min despite adequate SpO2 2

Critical point: Normal SpO2 does not exclude hypercapnia or respiratory acidosis, especially in patients on supplemental oxygen. 1

Documentation Requirements

In emergency situations, oxygen may be given without a formal prescription, but you must document: 1

• Oxygen delivery device used 1
• Flow rate or FiO2 1
• Target saturation range 1
• Initial and subsequent SpO2 readings 1
• Clinical response 1

Weaning Oxygen

• Lower concentration if patient clinically stable and SpO2 above target range for 4-8 hours 2, 3
• Discontinue when stable on low-concentration oxygen with saturation within target range on two consecutive observations 2, 3

Common Pitfalls to Avoid

Excessive oxygen in COPD is dangerous: 30% of COPD patients receive inappropriately high oxygen concentrations in ambulances, and 35% continue receiving excessive oxygen in hospital. 1 Oxygen saturations >92% in COPD patients are associated with increased mortality (OR 1.98 for 93-96%, OR 2.97 for 97-100% compared to 88-92%). 4

Do not abruptly stop oxygen if respiratory acidosis develops from excessive oxygen - gradually reduce concentration while monitoring closely. 1

Hyperventilation diagnosis requires caution: Exclude organic illness before attributing symptoms to hyperventilation, and never use paper bag rebreathing (dangerous). 1