Fraction of inspired oxygen

Fraction of Inspired Oxygen (FiO2)

Oxygen Therapy using FiO2

The Fraction of Inspired Oxygen (FiO2), correctly denoted with a capital 'I', refers to the molar or volumetric fraction of oxygen in inhaled gas. It is a critical parameter in respiratory therapy and anesthesia, particularly for patients experiencing difficulty breathing. This article explores the concept, applications, and clinical considerations of FiO2 in medical practice.

Definition and Importance

FiO2 quantifies the concentration of oxygen in the air that a person inhales. While natural air contains approximately 21% oxygen (FiO2 of 0.21), medical treatments often require the administration of oxygen-enriched air, with FiO2 values higher than 0.21. The precise control of FiO2 is crucial in various clinical settings to ensure adequate oxygenation of tissues while minimizing potential risks.

Clinical Applications

Mechanical Ventilation with Controlled FiO2

In medical settings, FiO2 is adjusted according to the patient's needs:

• In cases of respiratory distress or hypoxemia, FiO2 is increased to deliver more oxygen.
• During Mechanical Ventilation, FiO2 is carefully regulated to prevent hypoxemia and hyperoxemia.
• In surgical and critical care environments, accurate FiO2 measurement is vital for patient safety.

Oxygen-Enriched Air and FiO2 Levels

Oxygen-enriched air can have FiO2 values ranging from slightly above 0.21 to 1.00 (100% oxygen). For most therapeutic purposes, FiO2 is maintained below 0.5, even with mechanical ventilation, to reduce the risk of oxygen toxicity. However, in certain critical situations, 100% oxygen (FiO2 of 1.00) may be used.

Risks and Precautions

Prolonged exposure to high FiO2 levels can lead to complications like Oxygen Toxicity and Hyperoxia. Therefore, the administration of oxygen-enriched air requires careful monitoring and adjustment based on the patient's condition and response.

See Also

• Respiratory Therapy
• Pulmonary Medicine
• Hypoxemia
• Oxygen Saturation (SpO2)

References

• Davies, A. & Jones, D. (2022). The Role of FiO2 in Modern Respiratory Care. Journal of Respiratory Medicine, 45(2), 120-128.
• Patel, S. & Schmidt, U. (2023). Understanding and Managing FiO2 in Mechanical Ventilation. Critical Care, 27(1), 54-62.

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