Multiple layer fluid-containing cushion

A fluid-containing cushion comprising:

• at least three flexible chambers or containing fluid, said chambers including a top chamber, a bottom chamber, and a middle chamber disposed generally between said top and bottom chambers;
• each said chamber including a plurality of interior flexible tubes arranged for communication to define flow paths within hat chamber;
• said tubes in each said chamber being elongated and arranged in a parallel orientation in a generally horizontal row;
• flexible wall means for defining said tubes and including four sheets of a fluid-impervious, thermoplastic material arranged in four, generally superposed layers;
• said four sheets being sealed together at the cushion periphery with pairs of adjacent sheets also being sealed together along spaced-apart parallel lines within the periphery to define top, middle, and bottom rows of said tubes;
• said parallel lines of sealing terminating short of the peripheral seal at two opposite ends of said cushion to provide communication between said tubes in each row at each end of the cushion;
• each said tube in said top chamber being in substantially vertical registry with, and adjacent to, one of said tubes in said bottom chamber at an interface region to define a vertically registered pair of tubes;
• the tubes in said middle chamber being laterally offset from an adjacent pair of vertically registered top and bottom chamber tubes and being nested relative to said adjacent pair;
• said middle chamber communicating with one of said top and bottom chambers;
• and
• said middle chamber and said one top or bottom chamber containing a first fluid while the remaining chamber contains a second fluid that is different from said first fluid.