Patients at risk of severe pneumonia may experience respiratory distress and respiratory and circulatory failure, which can last about 7-10 days in young people and longer in older patients. Patients with severe pneumonia are at risk once they have a persistently elevated temperature, febrile convulsions, convulsions or cyanosis of the lips or mouth, and respiratory distress, and need a ventilator to help them breathe, as well as life-sustaining treatments such as antihypertensive drugs and hemodialysis. If the patient changes from coma to wakefulness and can breathe on his own, there is no need to use ventilator anymore, and the biochemical indexes tend to be stable, the condition is considered to be significantly improved, and the patient is gradually removed from the dangerous period. The duration of the danger period cannot be determined, but there is only a general time frame. Most of the cases of severe pneumonia are seen in the elderly, so care should be taken to turn the patient regularly to avoid the formation of decubitus ulcers, and to pay attention to good oral hygiene care during treatment to reduce the growth of bacteria in the mouth, and to pay attention to the daily diet, both to supplement nutrition and to avoid indigestible food.