What is the implication of delivering FiO2 of 0.24-0.40?

Delivering a fraction of inspired oxygen (FiO2) of 0.24-0.40 indicates a range of oxygen concentration that is not at maximum levels but rather moderate. This means that while the patient is receiving supplemental oxygen, the exact amount can vary based on factors like the patient's respiratory pattern, the device used for delivery, and the patient's overall oxygen requirements.

In clinical practice, a FiO2 within this range is often seen with nasal cannulas or simple face masks, where oxygen concentration may fluctuate with each breath. For instance, if a patient breaths in supplementary oxygen while simultaneously drawing in room air, the effective FiO2 may vary. Thus, it highlights the nuanced nature of oxygen delivery systems that don't provide a fixed or precise oxygen concentration, aligning well with the concept of variable oxygen delivery.

In this context, a high concentration of oxygen would refer to levels above 0.40, which isn't the case here. Similarly, low concentration generally implies an FiO2 below 0.24, and continuous high flow would typically describe systems delivering a consistently high oxygen flow, which does not apply to the specified range. Therefore, the best understanding comes from recognizing the variability involved in delivering an FiO2 of 0