There's not really a synthetic oxygen-carrying blood substitute that's commonly used. Turns out it's actually pretty hard to get right. https://en.wikipedia.org

There's not really a synthetic oxygen-carrying blood substitute that's commonly used. Turns out it's actually pretty hard to get right. https://en.wikipedia.org/wiki/Blood_substitute https://en.wikipedia.org/wiki/Blood_substitute has some info on different approaches and products that were/are sometimes used, but the short story is: not really.