ASA classification is generally divided into six grades: ASA1 is a healthy patient who can tolerate surgical anesthesia; ASA2 is a patient with mild systemic disease and no functional impairment who can tolerate surgical anesthesia; AS3 is a patient with severe systemic disease and some functional impairment, but can still tolerate anesthesia; ASA4 is a patient with severe systemic disease and a lifelong need for uninterrupted treatment with anesthesia The risk is extremely high and requires adequate and meticulous preanesthetic preparation; ASA grade 5 is a dying patient who is unlikely to survive within 24 hours, regardless of surgery; ASA grade 6 is a brain-dead patient.