What are the risks of administering 100% Oxygen (O2) and how can they be mitigated?

From the Guidelines

The administration of 100% oxygen should be limited to less than 24 hours when possible, and the lowest effective oxygen concentration should be used to maintain adequate saturation, typically SpO2 92-96% for most adults, to mitigate the risks of oxygen toxicity, absorption atelectasis, and other complications. The risks of 100% oxygen administration include:

• Oxygen toxicity, which can cause diffuse alveolar damage, haemorrhage, alveolar collapse, infiltration of inflammatory cells, necrosis, apoptosis, and injury to the endothelium and epithelium in the lungs 1
• Absorption atelectasis, which occurs when nitrogen is washed out of alveoli, leading to collapse
• Delay in recognition of clinical deterioration
• Potentially worse outcomes in mild-to-moderate stroke
• Specific risk in patients with previous bleomycin lung damage or with paraquat poisoning or acid aspiration
• Unknown risk–benefit balance in acute coronary artery disease with normal oxygen saturation
• Association with increased risk of death in survivors of cardiac arrest and among patients on ICUs

To mitigate these risks, the following strategies can be employed:

• Use the lowest effective oxygen concentration to maintain adequate saturation
• Gradually wean to lower concentrations as clinically appropriate
• Consider using lower concentrations (30-60%) with periodic assessment of arterial blood gases for patients requiring prolonged oxygen therapy
• Use positive end-expiratory pressure (PEEP) of 5-10 cmH2O to prevent atelectasis in mechanically ventilated patients
• Maintain strict oxygen saturation targets (typically 90-95%) and avoid hyperoxia in neonates

The British Thoracic Society guideline for oxygen use in adults in healthcare and emergency settings recommends a target saturation range of 94-98% for acutely ill patients, except those at risk of hypercapnic respiratory failure, who should have a target saturation range of 88-92% 1. The guideline also emphasizes the importance of maintaining a physiological target saturation range to guide staff to administer oxygen in a concentration to treat hypoxaemia without the risks of hyperoxaemia 1.

From the Research

Risks of 100% O2

• The use of 100% oxygen can lead to carbon dioxide retention in patients with chronic obstructive pulmonary disease (COPD) 2.
• High concentrations of oxygen can also worsen respiratory acidosis in COPD patients 3.
• Additionally, 100% oxygen can increase the risk of fire and explosion, particularly in the presence of sparks or open flames.

Mitigating the Risks

• Controlled oxygen therapy, using devices such as Venturi masks, can help minimize the risk of carbon dioxide retention and respiratory acidosis 2, 3.
• Monitoring arterial blood gas levels and adjusting oxygen therapy accordingly can also help mitigate these risks 2, 3.
• Using non-invasive ventilation (NIV) with helium-oxygen mixtures can help reduce the effort to breathe and improve gas exchange in COPD patients 4.
• Mechanical ventilation with low respiratory rates and careful attention to air-trapping can also help prevent dynamic hyperinflation and acid-base disturbances in COPD patients 5.

Oxygen Delivery Methods

• Venturi masks and nasal prongs are commonly used to deliver oxygen therapy in COPD patients 3.
• Non-invasive ventilation (NIV) with helium-oxygen mixtures can be an effective alternative to traditional oxygen therapy 4.
• Mechanical ventilation can be used in severe cases of respiratory failure, but requires careful management to avoid complications 5.