In interstitial lung disease, oxygen is inefficiently transferred into the capillary space, leading to the decreased partial pressure of oxygen in the blood. Why does a person with interstitial lung disease use a portable oxygen delivery service?

• A. An oxygen delivery service delivers oxygen directly to the tissues.
• B. Portable oxygen delivery service increases the partial pressure of oxygen in the blood by delivery of oxygen directly to the blood vessels.
• C. A person with interstitial lung disease uses a portable oxygen delivery service since it spontaneously reverses lung damage.
• D. Portable oxygen delivery service increases the concentration of oxygen inhaled, resulting in increased partial pressure of oxygen in the blood.

Answer: (D)