When the prey is suffocated the snake will loosen the coils and stops biting ( holding ) the prey. When the snake is loose, it will start to locate the head end of the prey by smell, and normally it will start with the headfirst approach. As the prey get's further into the mouth of the snake, helped by the backwards curved teeth, and the 2 bottom jaws, The snake can unhinge his lower jaws, to make room for the prey to go down. As the prey gets bigger, the snake will use the back part of his lungs to store some air in, so he doesn't have to breath, if needed.  Otherwise you can see ( and hear ) the air coming from the small round air ventricle on the lower middle of the mouth. Actually the snake moves slowly over the prey, instead of pulling it in.  With a good feed an adult female can go up to 1 year without food... in the wild.... in a severe case !!!!!!