Hollow spot, dead spot, whatever you want to call it. It does not exist inside the thoracic cavity, period. The shots in question are above the spine and hit muscle, ligaments, bone and basically nothing vital. If you slip an arrow directly under the spine, along with both lungs you are going to cut this little structure called the aorta, not compatible with life. It does not matter what state of exhale/inhale the animal is in, the lungs and the thorax expand and contract together. These are poor shots that hit in a non vital area. Would be the same as shooting one in the ham and saying got him in the dead spot.