Each leg of a U tube blanket is configured to have at least one row of holes extending substantially along the length thereof. The size of the holes is incrementally increased from the proximal portion that is closest to the air inlet cross section of the blanket where heated air is input to the blanket for inflating the same to the distal portion of the legs of the blanket. For an embodiment of the inventive blanket, the plurality of vent holes along each leg of the blanket are grouped into a number of sections, for illustration purposes three, with the vent holes in each section having the same dimension. With the size of the holes being incrementally larger along the leg away from the heat source, a greater amount of warm air is output at the distal portion of the blanket to compensate for the distance the warm air needs to travel before it is vented from the blanket. As a result, a substantially evenly distributed bath of warm air is output from the legs of the blanket to the sides of the patient so that the patient is evenly warmed along his entire body. Straps that are separable from the legs of the blanket are provided to secure the blanket to the patient.
