From the Guidelines
A PaO2 of 68 mmHg indicates mild hypoxemia, which may require supplemental oxygen therapy depending on the patient's symptoms and underlying health conditions, as suggested by the 2016 ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 1.
Clinical Implications
The normal range for PaO2 is typically 80-100 mmHg at sea level, and a value of 68 mmHg suggests that oxygen transfer from the lungs to the bloodstream is somewhat impaired but not severely compromised. According to the BTS guideline for oxygen use in adults in healthcare and emergency settings 1, oxygen therapy is less effective in certain causes of tissue hypoxia, such as anaemia, where the carrying capacity of haemoglobin is reduced.
Treatment and Management
Treatment depends on the underlying cause of the hypoxemia and may include supplemental oxygen if the patient is symptomatic or has other concerning vital signs. The 2016 ESC guidelines recommend oxygen therapy in patients with acute heart failure and SpO2 <90% or PaO2 <60 mmHg to correct hypoxaemia 1.
Monitoring and Follow-up
Regular monitoring of oxygen saturation (SpO2) using pulse oximetry would be recommended to track changes in oxygenation status, as suggested by the 2016 ESC guidelines 1. This allows for timely adjustments to oxygen therapy and other treatments as needed to maintain adequate oxygen delivery to tissues.
Key Considerations
- The body compensates for mild hypoxemia by increasing respiratory rate and cardiac output to maintain adequate oxygen delivery to tissues.
- Patients with underlying cardiopulmonary conditions may experience more severe symptoms and require closer monitoring and more aggressive treatment.
- The fraction of inspired oxygen (FiO2) should be increased up to 100% if necessary, according to SpO2, unless contraindicated, as stated in the 2016 ESC guidelines 1.
From the Research
Understanding PaO2 Levels
- PaO2, or arterial partial pressure of oxygen, is a measure of the amount of oxygen in the blood.
- A PaO2 level of 68 mmHg is considered low, as normal PaO2 levels typically range from 75 to 100 mmHg 2.
Clinical Significance of Low PaO2
- Low PaO2 levels can indicate hypoxemia, a condition where the body, or a region of the body, is deprived of adequate oxygen supply 2.
- In patients with traumatic brain injury, PaO2 levels less than 60 mmHg have been associated with poor outcomes 3.
- In patients with acute respiratory distress syndrome (ARDS), the optimal PaO2 target is unclear, but a study suggested that targeting a PaO2 range of 55 to 70 mmHg may be beneficial 4.
Oxygen Therapy Targets
- The American Association for Respiratory Care recommends aiming for an oxygen saturation range of 94-98% for most hospitalized patients, and 88-92% for those with chronic obstructive pulmonary disease (COPD) 5.
- For patients with ARDS, the optimal oxygen target is still uncertain, but a conservative approach targeting a PaO2 range of 55 to 70 mmHg may be considered 4.
Management of Hypoxemia
- Hypoxemia can be managed with supplemental oxygen therapy, and the choice of oxygen device and flow rate depends on the severity of hypoxemia and the patient's underlying condition 5.
- In patients with COPD, long-term oxygen therapy (LTOT) has been shown to improve survival in those with severe resting hypoxemia, but its effectiveness in patients with moderate hypoxemia is unclear 6.