When might oxygen therapy be indicated in patients with anemia?

Oxygen therapy may be indicated in patients with anemia particularly when hemoglobin levels are low enough to cause significant hypoxemia. Anemia results in a reduced capacity of the blood to carry oxygen due to decreased levels of hemoglobin, the protein in red blood cells that binds oxygen. If the hemoglobin concentration falls below a certain threshold, it can lead to inadequate oxygen delivery to tissues, resulting in hypoxemia, which is an abnormally low level of oxygen in the blood.

In such cases, supplemental oxygen can help increase the availability of oxygen to the tissues despite the reduced hemoglobin levels. This is especially critical when oxygen saturation falls to levels that could impair organ function or lead to symptoms like dyspnea or fatigue. By providing supplemental oxygen, you are primarily addressing the immediate need for increased oxygenation regardless of the low hemoglobin levels.

In contrast, situations where hemoglobin levels are high, oxygen saturation is already elevated, or the patient is asymptomatic do not warrant the use of oxygen therapy, since oxygen delivery to tissues is likely adequate in those scenarios. Therefore, B is the correct choice, as it directly addresses the conditions under which oxygen therapy becomes necessary in managing the effects of anemia.