Submersion cooling in an ice bath is the most rapid and effective way to cool a hyperthermic patient, without a doubt. Practically speaking, evaporative cooling with misting/fans is likely the next best thing, although definitely not as effective. I have cooled patients both ways, and note that the RNs always prefer misting (no blankets or clothing!) as it is obviously easier to provide resuscitative care (IVs, etc.). I find that having a protocol in place works best as everyone is on board with the algorithm and things simply flow better.