When is the majority of oxygen delivered during continuous oxygen delivery?

The correct answer emphasizes that the majority of oxygen is delivered during the first half of inspiration. This is based on the mechanics of breathing and the flow of gases during ventilation. During inhalation, the diaphragm and intercostal muscles contract, creating a negative pressure in the thoracic cavity that allows air to flow into the lungs. Because of this dynamic, the airflow is more pronounced during the initial part of inspiration as the lungs expand at a more rapid rate to accommodate incoming air.

Additionally, during this phase, the pressure gradient between the atmospheric pressure and the pressure within the lungs is greatest, allowing for a more efficient and effective transfer of oxygen. As a result, the lungs receive a larger volume of oxygen during this time compared to the latter portion of inspiration or during expiration, when the pressure differences begin to equalize and airflow decreases.

This understanding is critical for the effective application of oxygen therapy, as ensuring that patients receive oxygen at the right time can significantly enhance respiratory function and overall oxygenation.