At what SpO2 (peripheral capillary oxygen saturation) level should oxygen therapy be administered?

Oxygen Administration Thresholds Based on SpO2

Oxygen therapy should be initiated when SpO2 falls below 92% in most patients, with a target saturation range of 94-98%, while patients at risk for hypercapnic respiratory failure (COPD, obesity hypoventilation, cystic fibrosis) should receive oxygen when SpO2 is ≤88% with a target range of 88-92%. 1

Standard Oxygen Initiation Thresholds

For Patients WITHOUT Risk of Hypercapnic Respiratory Failure

• Start oxygen when SpO2 <92% and strongly recommend starting when SpO2 <90% 1
• Target saturation range: 94-98% 1
• Use nasal cannulae at 2-6 L/min or simple face mask at 5-10 L/min as initial therapy 1
• If SpO2 <85%, use reservoir mask at 15 L/min 1
• Maintain SpO2 no higher than 96% to avoid hyperoxemia, which has been associated with increased mortality in a dose-dependent manner 1, 2

For Patients WITH Risk of Hypercapnic Respiratory Failure

This includes patients with:

• COPD 1
• Cystic fibrosis 1
• Obesity hypoventilation syndrome 1
• Neuromuscular disorders 1
• Chest wall disorders 1

Oxygen thresholds for at-risk patients:

• Start oxygen when SpO2 ≤88% 1, 2
• Target saturation range: 88-92% 1
• Use 24% or 28% Venturi mask or 1-2 L/min via nasal cannulae 1
• Stop oxygen when SpO2 >92% to prevent hypercapnia 2
• Measure arterial blood gases after 30-60 minutes to confirm PCO2 is not rising 1

Critical Clinical Scenarios

Acute Severe Hypoxemia (SpO2 <85%)

• Use reservoir mask at 15 L/min immediately 1
• Applies to: acute hypoxemia of unknown cause, severe asthma, pneumonia, deteriorating interstitial lung disease 1

COVID-19 Specific Guidance

• Start supplemental oxygen if SpO2 <92% (suggested) 1
• Strongly recommend starting oxygen if SpO2 <90% 1
• Maintain SpO2 no higher than 96% to avoid hyperoxemia 1

Pregnancy and Labor

• Target range: 94-98% for pregnant women with acute illness, trauma, or sepsis 1
• Same 88-92% target applies if at risk for hypercapnic respiratory failure 1

Monitoring and Adjustment Algorithm

Step 1: Initial Assessment

• Measure SpO2 continuously with pulse oximetry 1
• Identify if patient has risk factors for hypercapnia 1

Step 2: Initiate Oxygen Based on Risk Category

• No hypercapnia risk: Start at SpO2 <92%, target 94-98% 1
• Hypercapnia risk: Start at SpO2 ≤88%, target 88-92% 1

Step 3: Titrate Oxygen Delivery

• Adjust FiO2 to maintain target range 1
• Stop oxygen when upper limit exceeded (>98% or >92% respectively) to prevent hyperoxemia 2

Step 4: Verify with Blood Gases

• Obtain arterial blood gas 30-60 minutes after initiating therapy 1
• If PCO2 is normal in presumed at-risk patient, can adjust target to 94-98% 1
• Recheck if PCO2 rises or patient deteriorates 1

Common Pitfalls to Avoid

Do Not Give Routine Oxygen to Non-Hypoxemic Patients

• 60% of patients with hyperoxemia had SpO2 within or below target range, indicating excessive oxygen administration 3
• Most patients with myocardial infarction, stroke, minor pulmonary embolism, and pleural effusions are not hypoxemic and do not require oxygen 1
• Unnecessary oxygen may increase infarct size in acute coronary syndromes 1

Avoid Sudden Oxygen Cessation in Hypercapnic Patients

• Never abruptly stop oxygen in patients with suspected hypercapnic respiratory failure 1
• Sudden cessation causes life-threatening rebound hypoxemia with rapid SpO2 fall below baseline 1
• Step down gradually to 24-28% Venturi or 1-2 L/min nasal cannulae 1

Special Populations Requiring Lower Targets

• Paraquat poisoning and bleomycin toxicity: Target SpO2 85-88% as supplemental oxygen may worsen lung injury 1
• Avoid oxygen unless patient is hypoxemic in these cases 1

Hyperventilation/Anxiety

• Pure hyperventilation from panic attacks does not require oxygen therapy 1
• Exclude organic illness first 1
• Do not use paper bag rebreathing as it may cause dangerous hypoxemia 1