From the Guidelines
Supplemental oxygen when not medically necessary can cause confusion, particularly in individuals with chronic obstructive pulmonary disease (COPD), at flow rates generally above 2-3 liters per minute. This is due to oxygen-induced hypercapnia, where excessive oxygen suppresses the respiratory drive in people whose breathing is normally stimulated by low oxygen levels rather than high carbon dioxide levels 1. The British Thoracic Society guideline for oxygen use in adults in healthcare and emergency settings highlights the importance of titrating oxygen therapy to the individual patient's needs, using the lowest effective flow rate and monitoring oxygen saturation regularly to prevent complications such as confusion, headache, dizziness, and in severe cases, seizures 1. Key points to consider include:
- Oxygen flows should typically be kept between 1-2 liters per minute to maintain oxygen saturation around 88-92% in COPD patients, rather than the higher 94-98% target for most patients 1.
- Uncontrolled supplemental oxygen therapy can be harmful to patients who are at risk of hypercapnic respiratory failure, especially if the PaO2 is raised above 10 kPa 1.
- High-concentration oxygen therapy has been associated with increased risk of death in some patient groups, such as patients with mild and moderate strokes, survivors of cardiac arrests, and ICU patients 1. Healthcare providers should exercise caution when administering supplemental oxygen, taking into account the individual patient's condition, oxygen saturation levels, and potential risks of oxygen toxicity 1.
From the Research
Supplemental Oxygen and Confusion
- There is evidence to suggest that supplemental oxygen, when not needed, can cause confusion and other adverse effects in patients 2.
- Hyperoxia, or high levels of oxygen in the blood, has been linked to increased mortality and morbidity in critically ill patients, including those with cardiac arrest, stroke, and traumatic brain injury 2.
Flow Rates and Hyperoxia
- The flow rate of supplemental oxygen required to create hyperoxia is not clearly established, but studies suggest that flow rates above 5 L/min may increase the risk of hyperoxia 3.
- One study found that patients with SpO2 levels above 95% were at increased risk of hyperoxia, and that supplemental oxygen should be administered with caution in these patients 4.
- Another study found that SpO2 levels above 100% were associated with a high risk of hyperoxia, and that titration of supplemental oxygen to normoxia is advised to avoid the negative effects of both hyperoxia and hypoxia 4.
Prevention of Hyperoxia
- Guidelines recommend titrating supplemental oxygen to physiological levels to avoid hyperoxia, and using SpO2 levels as a guide to avoid hyperoxia 5.
- However, one study found that SpO2-based oxygen titration may not be effective in preventing hyperoxia in all patients, and that healthcare providers should be cautious when administering supplemental oxygen to patients without clear respiratory compromise 5.