<s>[INST] my stepson had a brain aneurysm five years ago and he is vent dependent and Is fed through a g-tube. He is also not mobile. requires 24 hour care. last night his heart rate was 39-40 and his oxygen was 99-100. His heart rate has never dropped and stayed that low. it will occasionally drop if he is cold but as soon as we put blankets on him and make him warm his heart rate goes back to 50 s. [/INST] Hi, There are other reasons that heart rates can become low and fail to correct and perhaps in your stepson, one consideration would be an infection in the bloodstream from either a bladder, kidney, skin or pulmonary infection.  Low heart rates that do not correct may be signalling a situation where bacteria have gained access to the bloodstream and are beginning to affect his hemodynamics.  If he is at home I would contact his doctor and have someone come out to take a look at him and consider getting some labs and/or other tests performed. Hope I have answered your query. Let me know if I can assist you further.  </s>