What are the risks of prolonged high FiO2 and how can nurses mitigate oxygen toxicity in long-term therapy?

• A. Dehydration and electrolyte imbalance; mitigate by fluid restriction.
• B. Headache only; mitigate with analgesics.
• C. Oxygen toxicity with mucous membrane drying; mitigate with humidification.
• D. Risks include absorption atelectasis, oxidative stress, and lung injury; mitigation includes using the lowest FiO2 to maintain target SpO2, continuous monitoring, ABG evaluation, titration, and periodic reassessment for toxic effects.

Answer: (D)

When oxygen is given at high concentrations for a long time, the body can experience oxygen toxicity because excess oxygen forms reactive oxygen species that damage lung tissue. The main risks are absorption atelectasis from nitrogen washout leading to alveolar collapse, oxidative stress that injures the alveolar-capillary membrane and can cause edema, and potential progression to lung injury with ongoing exposure.

Mitigation hinges on using the lowest FiO2 that achieves the patient’s target oxygenation. Monitor continuously with pulse oximetry and use arterial blood gases to guide adjustments and confirm adequate, not excessive, oxygenation. Titrate FiO2 and reassess frequently to determine if levels can be reduced, and watch for early signs of toxicity. Humidification helps comfort and mucosal hydration but does not prevent oxygen toxicity.