The typical clinical manifestations of respiratory failure are as follows: 1) respiratory system: shortness of breath, shallow and rapid breathing, dyspnea, and even cyanosis and hypoxia; 2) nervous system: trance, headache, drowsiness; 3) cardiovascular system: palpitations, arrhythmia, lower limb edema; 4) digestive system: black stool, vomiting blood, vomiting coffee-like gastric contents. The elderly have weak resistance and poor reaction ability, often combined with chronic underlying diseases, therefore, the elderly have atypical respiratory failure, no pre-existing manifestations such as dyspnea, and directly appear consciousness disorders, such as mental confusion, gibberish, delirium, unresponsiveness, etc. The presence of neurological and gastrointestinal symptoms in the elderly requires consideration of the possibility of combined respiratory failure.