The problem is that most of the heat transfer in an oven is radiant, so a transparent liquid in a transparent dish is going to get very little heat transfer. Though the air is transparent as well, it need much less heat to get to temperature than water does. One option is to use a non-transparent dish.
The emergency treatment of polycythemia (e.g., in hyperviscosity or thrombosis) is by venesection, the removal of blood from the circulation. Depending on the underlying cause, venesection may also be used on a regular basis to reduce the red blood cell count.
The outlook on polycythemia depends on the underlying cause. Overall the general outlook is favorable for people with this condition, especially those with secondary causes. The outlook for primary polycythemia is fair. While it is typically incurable and long-standing, for many people, it is controllable and treatable. For example, untreated, polycythemia vera (PV) was initially thought to have a poor prognosis with a life expectancy of one to two years from the time of diagnosis. However, polycythemia vera prognosis is now greatly improved to 10-15 years survival after diagnosis with treatment by phlebotomy alone.