A mechanically ventilated client has received an FIO2 of 0.80 for 72 hours. Which new finding is most consistent with pulmonary oxygen toxicity?
1Substernal discomfort, a dry cough, and worsening oxygenation with new diffuse crackles✓ Correct answer
2Unilateral calf swelling, sudden pleuritic pain, and a new right bundle-branch block
3Bradycardia, widened pulse pressure, and an unequal pupillary response
4Polyuria, intense thirst, and an increasing serum sodium concentration
Explanation
Prolonged exposure to a high inspired oxygen concentration can damage the alveolar-capillary membrane. Early pulmonary manifestations include substernal discomfort, dry cough, dyspnea, diffuse crackles, and worsening gas exchange. The nurse should report the change and collaborate to use the lowest oxygen concentration that achieves the prescribed target while optimizing ventilatory support. The other clusters suggest pulmonary embolism, increased intracranial pressure, or diabetes insipidus.
Clinical reasoning High oxygen exposure generates reactive oxygen species that injure pulmonary epithelium and endothelium, causing inflammation, reduced compliance, and impaired diffusion.
Decision rule Trend oxygen dose and duration together. New respiratory symptoms or deteriorating gas exchange during prolonged high-FIO2 therapy require reassessment of the oxygen and ventilator strategy.
Scenario 48-year-old male, ARDS on mechanical ventilation with FiO2 100% for 30 hours. New retrosternal chest discomfort, non-productive cough, and decreasing lung compliance on ventilator settings.
Pulmonary oxygen toxicity — Inflammatory lung injury caused by prolonged exposure to a high inspired oxygen concentration.
FIO2 — The fraction of inspired oxygen delivered to the client, expressed as a decimal or percentage.
FiO2 weaning — Reduce inspired oxygen fraction to <60% as soon as tolerated to minimize O2 toxicity.