There are those who choose not to have blood transfusions and choose non-blood expanders, in cases where deemed necessary by the medical establishment, usually in emergency cases or acute/critical health issues.
The Mg (magnesium) and K (potassium) concentration levels are high in it also...
Non-blood expanders are much safer than blood transfusions, as each person's blood is different from others (as a fingerprint).
The non-blood substitutes main job is to carry life giving oxygen.... The patient is also given huge doses of "food" the bone marrow needs to build up the patient's own blood structure.
Well, anyway, that is as simple as I can explain it.....and I am not surprised the ocean water has so much in it and can be used as a non-blood substitute....