A waveform generation circuit 16 comprises an input terminal 28, a composing unit 21, a delay unit 23, a processing unit 25, a memory unit 27 and an output terminal 52. A displacement detector determines a displacement indicative signal indicative of the displacement of the CPR recipient’s chest toward the recipient’s spine. The substrate has a weight per unit area of 150 to 350 gm2. A handle is joined to the lid in a position outside of the entrance pathway, so that it does not interfere with insertion of pizzafoods into, or removal of pizzafoods from, the cooking chamber while the lid remains in the closed position.