What characteristic is essential for high-flow systems?

High-flow systems are designed to deliver a specific concentration of oxygen to patients, and this is achieved by ensuring that the flow rate of the oxygen provided equals or exceeds the patient's inspiratory flow. This characteristic is crucial because it allows the system to meet the patient's oxygen demands at all times, regardless of their breathing pattern.

When the flow rate matches or surpasses the patient's inspiratory flow, the patient receives a more consistent and accurate fraction of inspired oxygen (FiO2). This prevents room air from mixing with the oxygen supply, ensuring that the necessary oxygen concentration is delivered without dilution from ambient air. High-flow systems are particularly beneficial for patients who have increased oxygen needs or who may be experiencing significant respiratory distress, as they maintain adequate oxygenation.

In contrast, other statements highlight drawbacks or limitations that do not apply to high-flow systems. Specifically, if the flow rate is less than the patient's inspiratory flow, the system would be inadequate as it would not provide sufficient oxygen, resulting in variable and lower FiO2. Furthermore, high-flow systems are not limited exclusively to patients with mild hypoxemia, as they can be instrumental for those with more severe hypoxemia or respiratory conditions requiring close management of oxygen delivery.