Autoionizing Rydberg states in zero field exhibit lifetimes scaling as the cube of the principal quantum number, n(3), but in a linearly polarized static or microwave field the lifetimes scale as n(4) due to l mixing. To mimic the effects of collisions with charged particles we have examined the effect of a circularly polarized field on the decay rate and find longer lifetimes than in a linearly polarized field, but not an n(5) dependence.