From the Guidelines
Using supplemental oxygen when you don't medically need it can be harmful to your health, as it can lead to oxygen toxicity, worsening of hypercapnic respiratory failure, and increased risk of death in certain patient groups. Breathing higher concentrations of oxygen than necessary can damage lung tissue through the formation of excessive free radicals, as seen in animal models where prolonged exposure to high concentrations of oxygen leads to diffuse alveolar damage, haemorrhage, and necrosis 1. The BTS guideline for oxygen use in adults in healthcare and emergency settings highlights the clinical risks associated with unnecessary oxygen use, including worsening of hypercapnic respiratory failure, delay in recognition of clinical deterioration, and potentially worse outcomes in mild-to-moderate stroke 1.
Some of the key risks associated with unnecessary oxygen use include:
- Worsening of hypercapnic respiratory failure
- Delay in recognition of clinical deterioration
- Potentially worse outcomes in mild-to-moderate stroke
- Increased risk of death in survivors of cardiac arrest and among patients on ICUs
- Association 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.
It is essential to note that the body's respiratory system is carefully calibrated to maintain proper oxygen levels, and introducing excess oxygen disrupts this balance. Healthy individuals already maintain optimal blood oxygen saturation (95-100%) through normal breathing, so supplemental oxygen provides no benefit and only introduces potential risks. Oxygen should only be used under medical supervision when there is a documented need, such as in certain respiratory conditions or at high altitudes. The guideline emphasizes that 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.
From the Research
Risks of Unnecessary Oxygen Use
- Using oxygen when it is not needed can be harmful due to the risk of hyperoxemia, which can cause oxidative stress and inflammation 2, 3.
- Hyperoxemia can lead to pulmonary and systemic effects, including altered surfactant protein composition, reduced mucociliary clearance, and histological damage 3.
- Excessive oxygen supplementation can also cause vasoconstriction, reduction in coronary blood flow and cardiac output, and alter microvascular perfusion 3.
Guidelines for Oxygen Therapy
- Oxygen therapy should only be initiated when the patient's SpO2 is below a certain threshold, which depends on the presence of risk factors for oxygen-induced hypercapnia 2.
- The delivered oxygen fraction should be titrated to maintain SpO2 within a target range, and oxygen therapy should be stopped when the upper limit of SpO2 is surpassed 2.
- A conservative oxygen therapy approach, aimed at maintaining arterial oxygenation within physiological range, has been shown to be well tolerated and may improve outcomes in critically ill patients 3.
Consequences of Hyperoxia
- Hyperoxia can increase the level of reactive oxygen-derived free radicals, leading to oxidative cellular injury 4.
- However, the human lung is more resistant to hyperoxic oxidative damage than previously expected, and absorption atelectasis is the most frequently pulmonary effect of inhalation of a high inspired oxygen fraction 4.
- Hyperoxia can also have detrimental effects on the health status and survival of newborns and adults, making it essential to carefully tailor oxygen therapy to individual needs 5.
Best Practices for Oxygen Therapy
- Oxygen therapy should be carefully tailored to relieve hypoxemia without provoking hyperoxia or hypercarbia 5.
- A thorough knowledge of the pathophysiological bases of hypoxemia and oxygen storage and delivery devices is necessary to administer oxygen therapy effectively 5.
- Clinicians should follow evidence-based practices, such as aiming for a specific SpO2 range and promoting early initiation of high-flow oxygen, to provide maximum benefit and avoid harm 6.