From the Guidelines
To prevent oxygen toxicity in patients requiring supplemental oxygen, clinicians should use the lowest effective oxygen concentration to achieve target oxygen saturation levels, typically 94-98% for most adults and 88-92% for those at risk of hypercapnic respiratory failure. Oxygen therapy should be titrated based on regular monitoring of oxygen saturation using pulse oximetry, with arterial blood gas measurements when necessary 1. For acute care settings, start with low-flow oxygen (2-4 L/min via nasal cannula) and adjust as needed, as recommended by the BTS guideline for oxygen use in adults in healthcare and emergency settings 1. In chronic oxygen therapy, flow rates typically range from 1-3 L/min. Time-limited oxygen therapy is preferred when possible, with clear documentation of target saturation ranges and duration in the patient's care plan. Some key considerations for specific patient populations include:
- Patients with COPD or other risk factors for hypercapnic respiratory failure, who should have a target saturation range of 88-92% pending blood gas results 1
- Patients with myocardial infarction and acute coronary syndromes, where unnecessary use of high concentration oxygen may increase infarct size 1
- Patients with stroke, where oxygen therapy may be harmful for non-hypoxaemic patients with mild–moderate strokes 1
- Patients with poisoning or drug overdoses, where hypoxaemia is more likely with respiratory depressant drugs, and antidotes should be given if available 1 Oxygen toxicity occurs because high concentrations of oxygen generate excessive reactive oxygen species that damage cellular structures, particularly in the lungs and central nervous system. Regular reassessment of oxygen requirements is essential, with the goal of weaning supplemental oxygen as the patient's condition improves, and avoiding life-threatening rebound hypoxaemia when stepping down oxygen therapy 1.
From the Research
Definition of Oxygen Toxicity
Oxygen toxicity refers to the harmful effects of high concentrations of oxygen on the body's tissues and organs.
Guidelines for Preventing Oxygen Toxicity
To prevent oxygen toxicity in patients requiring supplemental oxygen, the following guidelines are recommended:
- Limiting hyperoxia to maintain arterial oxygen percent saturation (SaO2) greater than or equal to 90% is recommended 2
- The lowest possible concentration of oxygen that relieves tissue hypoxia is recommended in patients with adult respiratory distress syndrome 3
- Oxygen titration should be done, and with appropriate safeguards, lower oxygenation targets may be acceptable and possibly beneficial in many critically ill patients 4
- Titrate oxygen therapies to specific goals, avoiding hyperoxia and its associated adverse clinical outcomes 5
Risks of Oxygen Toxicity
The risks of oxygen toxicity include:
- Central nervous system and pulmonary toxicity, resulting in atelectasis, pulmonary edema, and seizures 3
- Lung damage due to normobaric hyperoxia 3
- A severe retinopathy (retrolental fibroplasia) in neonates during oxygen exposures 3
- Alveolar injury, pulmonary edema, and subsequent systemic inflammatory response 4
- Harmful hemodynamic effects, including peripheral and coronary vasoconstriction, and direct cellular toxicity through the production of reactive oxygen species 5
Importance of Oxygen Management
Oxygen management is crucial in critically ill patients, as hyperoxia can cause harm and is associated with increased mortality in certain patient populations 6, 4. Therefore, it is essential to implement precise oxygen titration and avoid liberal oxygenation practices 4.