The length of time a patient can live after a dilated pupil depends on the patient’s respiratory and circulatory function and the function of other organs, as well as the response to medications and instrumental support, and needs to be determined in conjunction with the cause and severity of the patient’s condition. If the patient has dilated pupils, no spontaneous breathing, unstable circulatory function, and combined organ failure, the patient may die at any time after all medications and instrumental support are withdrawn. If the pupils are dilated, but the circulation is stable, the blood pressure is stable, and the patient is not breathing on his own, but is dependent on ventilatory support, the patient may survive for some time. Some cells in the human body are more tolerant to oxygen and may still have the ability to divide and proliferate after death, but this does not mean that the person is not dead. Modern medicine considers a brain-dead patient to be declared dead because there is no subjective consciousness and he or she is unable to carry out life activities.