Hypoxia and Medicine

Why cant we ever give Oxygen I.V? I've been studying pathology/physiology and I just cant understand this notion. Don't get me wrong, this might seem like a preposterous question at first, but let me explain my reasoning. Basically in the lung alveolar, O2 diffuses inside the vessels, and gets carried away. The equation that sums up this mixing is given as: Oxygen content in blood=[Hb X O2(saturation)] + Partial pressure of O2. The O2 saturation is directly dependent on the Partial pressure of O2. Therefore, lets assume that we connect a chamber of pure 100% O2 to an arterial(or venous) line. We control the pressure of it, and the volume that enters the cannula. If so, aren't we doing exactly the same thing as the alveolar epithelium does. We have just removed the barrier of epithelium, and gave a direct access to the oxygen, hence catalyzing mixing and diffusion. I can't understand why this isn't possible? Talking about the physics of it, people are afraid of gas displacement. Like, the gas can go and clog up some artery, i.e bubbles in the arteries. That can also be prevented if we give O2 over time, under a slow pressure which will enhance mixing, and instead won't form bubbles. Also, blood is flowing under pressure, which naturally helps the mixing process. So, why is it not possible? I know I am missing some physical aspect in this idea. When I ask this question to my professor they just say stuff like "Are you crazy?", without ever explaining the logic behind it. If there are physicists/pulmonary physicians, maybe they can shed some light in this subject because its really bothering my head. In emergency situations, we have to disrupt homeostasis, one way or the other. We disrupt homeostasis whenever a patient is in emergency situations like respiratory failure or ARDS/ALI (acute respiratory distress syndrome/acute lung injury). If giving O2 by this means is possible, imagine the implications and use of such technique. Instead of relying on ventilation, which causes tons of problem of its own, you could simply support the person on iv O2 while he recovers from his initial injury/condition/disease.