What is the target pO2 (partial pressure of oxygen) range for patients requiring oxygen therapy?

Target pO2 Range for Oxygen Therapy

For most patients requiring oxygen therapy, the target pO2 range should be 75-100 mm Hg (10-13 kPa), which corresponds to an oxygen saturation (SpO2) target of 94-98%. 1

Different Target Ranges Based on Patient Risk Factors

Standard Target Range (Most Patients)

• Target SpO2: 94-98% (corresponding to pO2 of approximately 75-100 mm Hg or 10-13 kPa) 1
• This range applies to most acutely ill patients without risk factors for hypercapnic respiratory failure 1
• This target ensures adequate tissue oxygenation while avoiding the risks of hyperoxia 1

Modified Target Range (At-Risk Patients)

• Target SpO2: 88-92% for patients with:
  • COPD (Chronic Obstructive Pulmonary Disease) 1
  • Other risk factors for hypercapnic respiratory failure (e.g., morbid obesity, cystic fibrosis, chest wall deformities, neuromuscular disorders) 1
• This lower target range helps prevent oxygen-induced hypercapnia in vulnerable patients 1
• Blood gas results should be checked after initiating oxygen therapy in these patients 1

Special Circumstances

• Target SpO2: 85-88% for patients with paraquat poisoning or bleomycin lung injury 1
• Target SpO2: 100% for patients with pneumothorax under observation (oxygen accelerates clearance) 1
• For carbon monoxide poisoning, give highest possible oxygen concentration regardless of saturation readings 1

Clinical Implementation

Initial Assessment

• Measure baseline SpO2 using pulse oximetry in all breathless and acutely ill patients 1
• Record the inspired oxygen device and flow rate on the observation chart with the oximetry result 1
• For patients with initial SpO2 below 85%, use a reservoir mask at 15 L/min initially 1
• For less severe hypoxemia, use nasal cannulae (2-6 L/min) or simple face mask (5-10 L/min) 1

Monitoring and Titration

• Adjust oxygen therapy to maintain SpO2 within the target range 1
• For patients at risk of hypercapnia, check arterial blood gases after 30-60 minutes of oxygen therapy 1
• If PCO2 is normal in at-risk patients, the target can be adjusted to 94-98% 1
• Be aware that pulse oximetry may be less accurate in patients with dark skin pigmentation 1

Avoiding Complications

Risks of Hyperoxia

• Unnecessary high oxygen concentrations may:
  • Increase infarct size in myocardial infarction 1
  • Be harmful in non-hypoxemic patients with mild-moderate strokes 1
  • Cause direct pulmonary toxicity 1
  • Lead to coronary vasoconstriction and decreased cardiac output 1
  • Delay recognition of clinical deterioration 1
  • Increase reactive oxygen species formation 2

Risks of Hypoxemia

• Prolonged exposure to PaO2 < 55-60 mm Hg should be avoided 2
• Severe hypoxemia can lead to tissue hypoxia, organ dysfunction, and cell death 1
• Brain function is particularly vulnerable to hypoxemia 1

Common Pitfalls

• Administering oxygen as standard care to patients without clear respiratory compromise can lead to occult hyperoxia 3
• Relying solely on SpO2 readings may still result in hyperoxemia in a significant proportion of patients 3
• Failure to recognize that many conditions (e.g., anemia, pleural effusions, minor pulmonary embolism) often do not require oxygen therapy 1

Evidence Quality and Considerations

• The most recent international consensus (2024) recommends targeting PaO2 of 75-100 mm Hg (10-13 kPa) in adults after cardiac arrest 1
• The British Thoracic Society (2017) guidelines provide comprehensive recommendations for various clinical scenarios 1
• Recent studies suggest a U-shaped relationship between PaO2 and mortality/morbidity in ICU patients 2
• Evidence indicates that avoiding both hypoxemia and hyperoxia is important for optimal outcomes 1, 2