Vacuum/heat formed cushion with pyramidal, inflatable cells

An inflatable cushion comprising a flexible gas impervious bottom wall, a preformed flexible gas impervious top sheet defining a plurality of air cells, and air-tight seals attaching the top sheet to the bottom wall at edges of the air cells except for limited sections between selected adjacent air cells defining passages for allowing fluid communication between the selected adjacent air cells;

• wherein each air cell includes an upper portion and a lower portion, the lower portion having a parallelepiped shape defined by four generally vertical side walls, the upper portion extending above the side walls of the lower portion, the upper portion of each air cell being defined by four substantially triangular panels which incline upwardly from the lower portion of the air cell and meet in an apex, giving the upper portion a substantially pyramidal shape at a first inflation pressure of the air cells, the side walls of the lower portion and the pyramidal upper portion being flexible and distensible so that the pyramidal upper portion becomes rounded and the side walls of the lower portion distend outwardly at a second inflation pressure of the air cells, the second inflation pressure being higher than the first inflation pressure, the plurality of air cells being in close proximity to one another so that the side walls of adjacent air cells engage one another when the side walls distend outwardly thereby defining a substantially level and continuous load supporting surface of the cushion at the second inflation pressure of the air cells.