Another thing that happens is as the person gets closer to death, the time between inhales widens. When breaths are towards 20-30 seconds apart, death may be happening very soon. I say "may" because there is always someone who may have this breathing pattern and live much longer. Overall, breaths will be getting more shallow and the time between inhales will space out.
There are exceptions to everything, but generally this is what you will see. Of course right now I want to tell you all the ways it could be different and how many ways breathing can look even with the above very general guidelines. The best thing to do is when you are going through this time, ask your hospice doctor or nurse about it and ask them to show you what you will be seeing. I do this with the people I care for. I show them some ways it can look and when it happens, they aren't as startled.
The pattern is called 'cheyne-stokes' respirations.
" ... Cheyne-Stokes respirations refer to a rhythmic change in respirations wherein breathing becomes shallower and shallower variably with a slowing in respiratory rate that culminates usually in complete cessation of breathing for several seconds to more than a minute. This is followed by progressively stronger respirations that become exaggerated and quite deep. This pattern is thought to result from abnormal brainstem responses to CO2 levels in the blood - initially undercompensating and then overcompensating. Cheyne-Stokes respirations can occur in other nonterminal disorders such as heart failure and stroke. It is interesting to note that patients who are able to speak generally say that no distress is associated with this breathing pattern. From this we may extrapolate to dying patients, who usually cannot speak with Cheyne-Stokes respirations, and presume that the syndrome is not disturbing to the patient. However, family members and clinicians may assume or project distress into this syndrome and thus often need to be coached. I usually explain that the pattern results from a breakdown in "cycling" between the lungs and the brain and that, as far as we know, it is not bothersome to the patient ... " Palliative Care Perspectives-- James L. Hallenbeck, MD