Blood oxygen below 80% is a very serious condition that can usually last for about 100 hours. The survival time can be longer if professional treatment is available. Blood oxygen below 80% is usually present in more serious inpatients and requires active observation of changes in the patient’s vital signs and timely detection of any signs of infection. If symptoms such as coughing, coughing up sputum, or difficulty in breathing occur, they need to be resuscitated in a timely manner, otherwise respiratory failure is likely to result. Patients can survive for up to six months without infection and with adequate nutritional care. During this period, family members and medical staff need to take full care of the patient to maintain the patient’s vital signs as much as possible and prolong the survival period.