When is oxygen primarily delivered during pulse-delivered oxygen therapy?

In pulse-delivered oxygen therapy, oxygen is primarily delivered during the first quarter of inspiration. This timing is crucial because it aligns with the natural flow and demand for oxygen in the lungs when the patient initiates inhalation. By delivering oxygen early in the inspiratory phase, the therapy maximizes the amount of oxygen that can be effectively transported to the alveoli, where gas exchange occurs.

The rationale behind this approach is based on the mechanics of breathing and the timing of oxygen delivery to coincide with the patient's inspiratory effort. By targeting the initial phase of inhalation, the delivered oxygen can be effectively utilized during the subsequent inhalation cycle, ensuring efficient oxygenation.

In contrast, the other options either involve inappropriate timing for effective delivery or do not align with the dynamics of pulmonary gas exchange. Therefore, delivering oxygen at the right moment is essential for optimizing treatment outcomes in patients using pulse-delivered oxygen therapy.