Should a person with heart failure receive oxygen (O2) therapy in the ambulance?

Oxygen Therapy for Heart Failure in the Ambulance

Oxygen should be administered in the ambulance only if oxygen saturation is below 90%, based on clinical judgment and pulse oximetry monitoring. 1

Evidence-Based Approach to Oxygen Administration

The European Society of Cardiology guidelines provide clear direction for prehospital oxygen use in acute heart failure:

• Oxygen therapy should be given based on clinical judgment unless oxygen saturation is <90%, in which case oxygen therapy should be routinely administered. 1
• Pulse oximetry monitoring must be instituted within minutes of patient contact in the ambulance. 1
• The treatment objective is to maintain SpO2 >90%. 1, 2

When NOT to Give Oxygen

Avoid routine oxygen administration in normoxemic patients (SpO2 ≥90-94%). The 2024 American Heart Association guidelines state that the effectiveness of oxygen in the first aid setting for patients with shortness of breath is unknown, and there is no direct evidence supporting routine oxygen use. 1

For patients with COPD comorbidity, it is potentially harmful to administer supplementary oxygen to achieve saturation >92%, as this increases mortality risk. 1

Clinical Decision Algorithm

Step 1: Immediate pulse oximetry measurement 1

• If SpO2 <90%: Start oxygen immediately
• If SpO2 90-94%: Use clinical judgment (consider respiratory distress, work of breathing, orthopnea)
• If SpO2 >94%: Oxygen not indicated

Step 2: Titrate oxygen delivery 1

• Target SpO2 >90% (not higher unless clinically indicated)
• For known COPD patients, target 88-92% to avoid hypercapnia 1

Step 3: Concurrent interventions 1, 2

• Position patient upright
• Consider non-invasive ventilation (CPAP) if respiratory distress persists
• Initiate medical treatment (vasodilators/diuretics based on blood pressure)

Important Caveats

Hyperoxia should be avoided. Research demonstrates that supplemental oxygen in normoxemic patients may cause coronary vasoconstriction, reduced coronary blood flow, and increased oxidative stress—potentially worsening outcomes. 3

Most acute heart failure patients present with normal or high blood pressure (mean systolic BP 144-170 mmHg in prehospital cohorts), not cardiogenic shock, and the majority do not require oxygen therapy. 1

The evidence for routine oxygen use in heart failure is weak. A randomized trial of long-term home oxygen therapy in chronic heart failure showed no quality-of-life benefit, and ambulatory oxygen studies demonstrated no improvement in breathlessness or exercise capacity. 4, 5

Continuous monitoring is essential because oxygen requirements may change rapidly during transport, and unnecessary oxygen should be discontinued. 1, 6