The volute (17) defines, on its periphery, a gas flow guide channel (100) which has is sensibly symmetrical in section with respect to an output plane (P) of its fins on its gas flow drive wheel (14). On either side of the wheel fins are annular walls, both these walls and the fins define disjoint guides for the gas flow. Each fin defines a left surface whose normal varies through three orthogonal directions along the length of the fin. The high speed centrifuge ventilator is of the type having a casing in which is a gas flow guide volute, a finned gas flow drive wheel rotating in the volute, and a drive (12) which rotates the wheel at more than 25000 revolutions per minute, preferably between 47000 and 56000 rpm. A gas flow aspiration loop (30) extends from an input (18) formed in the casing.; A passage (32) reverses the gas flow in a centrifugal way along an output plane (P) of the wheel. The casing has an output (20) for reversing the gas flow out of the volute. The guide channel (100) is progressively increased in the direction of the output (20).