include inflation means not shown a fabric strip 190 bridges across and is adhesively or otherwise suitably attached to the upper surface of crib 178 for lateral stability the cribs 176 and 178 and support member 172 are adhesively or otherwise suitably attached and the assembly including the tilting assembly 174 and cushion 180 are enclosed within a zippered mattress cover 175 as shown in fig2 fig2 illustrates the mattress 170 with the cushion 180 in a level condition for the patient 171 to lie normally thereon in this condition the cushion 180 and upper bladder 182 are fully inflated while the lower bladder 184 is uninflated fig3 illustrates tilting of the cushion 180 to about a 15 degree angle to one side by deflating the left side bladder 182b and by inflating the right side bladder 184a as seen in fig3 this lowers the left side of the cushion 180 and raises the right side thereof thereby providing a 34 trough 34 illustrated at 192 on the left side to prevent the patient 171 from falling off the mattress the patient 171 is thus 34 caught 34 by the upper crib 178 with the fabric strip 190 providing lateral stability to prevent the crib 178 from bowing outwardly fig4 illustrates tilting of the cushion 180 from the position of fig2 to about a 15 degree angle to the other side by deflating the right side upper bladder 182a and by inflating the left side lower bladder 184b this lowers the right side of the cushion 180 and raises the left side.