A method for making a hospital bed comprising: providing a support structure; coupling a pressure source to a controller; and positioning a hospital bed mattress to be carried by the support structure and having first and second ends (28, 29), and first and second sides (30, 31) extending between the first and second ends, the hospital bed mattress comprising a base foam layer comprising opposing first and second ends, the first end to receive a head of a patient, the second end to receive feet of the patient, an upper major surface and a lower major surface opposing the upper major surface, the upper major surface comprises a plurality of upper ribs extending transversely between the first side and the second side of the base foam layer, and a plurality of upper slots extending transversely between the first side and the second side of the base foam layer, and a plurality of transverse bladder pairs (551a - 551w) extending over the base foam layer and being coupled to the pressure source, the plurality of transverse bladder pairs extending between the first and second sides and are configured to provide longitudinal pressure differential and lateral pressure differential, wherein each transverse bladder pair of the plurality of transverse bladder pairs comprises first and second overlapping bladders, wherein the longitudinal pressure differential is generated by selectively inflating different transverse bladder pairs (551a-551w) and the transverse pressure differential is generated by selectively inflating only one of the first and second overlapping bladders (552a-552b), and a multi-layer removable encasement surrounding the base foam layer and the plurality of transverse bladder pairs. providing a support structure; coupling a pressure source to a controller; and positioning a hospital bed mattress to be carried by the support structure and having first and second ends (28, 29), and first and second sides (30, 31) extending between the first and second ends, the hospital bed mattress comprising a base foam layer comprising opposing first and second ends, the first end to receive a head of a patient, the second end to receive feet of the patient, an upper major surface and a lower major surface opposing the upper major surface, the upper major surface comprises a plurality of upper ribs extending transversely between the first side and the second side of the base foam layer, and a plurality of upper slots extending transversely between the first side and the second side of the base foam layer, and a plurality of transverse bladder pairs (551a - 551w) extending over the base foam layer and being coupled to the pressure source, the plurality of transverse bladder pairs extending between the first and second sides and are configured to provide longitudinal pressure differential and lateral pressure differential, wherein each transverse bladder pair of the plurality of transverse bladder pairs comprises first and second overlapping bladders, wherein the longitudinal pressure differential is generated by selectively inflating different transverse bladder pairs (551a-551w) and the transverse pressure differential is generated by selectively inflating only one of the first and second overlapping bladders (552a-552b), and opposing first and second ends, the first end to receive a head of a patient, the second end to receive feet of the patient, an upper major surface and a lower major surface opposing the upper major surface, the upper major surface comprises a plurality of upper ribs extending transversely between the first side and the second side of the base foam layer, and a plurality of upper slots extending transversely between the first side and the second side of the base foam layer, and a plurality of transverse bladder pairs (551a - 551w) extending over the base foam layer and being coupled to the pressure source, the plurality of transverse bladder pairs extending between the first and second sides and are configured to provide longitudinal pressure differential and lateral pressure differential, wherein each transverse bladder pair of the plurality of transverse bladder pairs comprises first and second overlapping bladders, wherein the longitudinal pressure differential is generated by selectively inflating different transverse bladder pairs (551a-551w) and the transverse pressure differential is generated by selectively inflating only one of the first and second overlapping bladders (552a-552b), and a multi-layer removable encasement surrounding the base foam layer and the plurality of transverse bladder pairs.