In hyperbaric therapy, what happens to blood oxygen content?

• A. It decreases
• B. It saturates haemoglobin with oxygen and increases dissolved oxygen in plasma
• C. It prevents oxygen delivery to tissues
• D. It uses heat to aid recovery

Answer: (B)

In hyperbaric therapy the key idea is that raising the pressure while breathing pure oxygen pushes a lot more oxygen into the blood. The high partial pressure of oxygen means more of it dissolves directly in the plasma (dissolved oxygen), thanks to Henry’s law. Hemoglobin becomes fully saturated at these high oxygen levels, so the additional oxygen carried by hemoglobin isn’t the main change; instead, the larger dissolved oxygen pool in the plasma boosts the total oxygen content and enhances its delivery to tissues. This helps tissues that are starved of oxygen, which is why HBOT is used therapeutically. The other options don’t fit: oxygen content doesn’t decrease, it doesn’t prevent oxygen delivery, and heat isn’t the mechanism by which HBOT increases oxygen content.