1 may be provided on a single side of the mattress 10 and thus may be attached to the bed frame along its midline not shown as shown in fig1 the interconnected tension webs 4 form a trapezoidal concave upward structure having a series of apertures 14 above which the bolster bladders 1 a 1 b sit fig1 also shows the vent valve 5 and pneumatic conduit air hose 6 to the bolster bladders 1 a 1 b the vent valve 5 permits a user to manually deflate the bolster bladders 1 a 1 b and dump the air to the environment without deactivating the blower thus the bolster 1 assembly can be provided separately and independently from a blower and may be retrofit onto existing beds if the bolster bladders 1 a 1 b are to be operated separately the vent valve 5 would include a pair of controls for operating separate valve bodies fig2 shows the bolster 1 assembly in place on an inflated air mattress 10 in this case the air mattress 10 has bladders 15 which are taller than wide due to a central seal in each segment the tension web 4 provides a strap like portion 4 a which extends between each pair of adjacent segments 15 the straps 2 at the lateral edge of the bolster bladder 1 a 1 b are wrapped around the straps 11 of the mattress bladders 15 which in turn are attached to the bed frame not.