For patients with poor tolerance, in addition to the general preparations mentioned in this paper, various special preparations are needed, as follows: 1, malnutrition: malnourished patients with protein deficiency, reduced ability to tolerate blood loss and shock, etc., easily cause tissue edema, affecting healing, and prone to serious infections, should be corrected before surgery, and strive to achieve a positive nitrogen balance. 2, hypertensive patients with blood pressure above 160/100mmHg may be at risk of cerebrovascular accident or acute heart failure during induction of anesthesia or surgery, and need to apply antihypertensive drugs to lower the blood pressure to below the above range, but it is not necessary to lower it to normal before doing surgery. 3. Heart disease: The mortality rate of surgery for heart patients is 2 or 8 times higher than that of general patients. The type of heart disease varies and so does its tolerance. (1) Well-tolerated heart disease includes: non-cyanotic congenital heart disease, rheumatic and hypertensive heart disease. (2) Poorly tolerated heart disease includes: coronary atherosclerotic heart disease, atrioventricular block prone to cardiac arrest. (3) Very poorly tolerated heart diseases include: acute myocarditis, acute myocardial infarction and heart failure, and surgery should be postponed except for emergency resuscitation. Precautions for the preparation of cardiac patients before surgery: ① patients with long-term use of low-salt diet and diuretic drugs, water and electrolyte imbalance, need to be corrected before surgery; ② anemic patients with poor oxygen carrying capacity, can be corrected with a small number of blood transfusions before surgery; ③ patients with arrhythmias, according to different reasons for different treatment, occasional ventricular asystole, generally do not need special treatment; ④ patients with acute myocardial infarction, within 6 months, do not perform elective (4) Patients with acute myocardial infarction should not undergo elective surgery within 6 months. In patients with heart failure, it is best to perform surgery after 3 to 4 weeks of heart failure control. 4, respiratory dysfunction: The main manifestation of respiratory insufficiency is dyspnea with slight activity, asthma and emphysema are the two most common chronic diseases. For severe pulmonary insufficiency, blood gas analysis and pulmonary function test should be done before surgery, and for those with infection, it must be controlled before surgery. Preoperative preparation: (1) Stop smoking for 2 weeks and encourage the patient to breathe deeply and cough. (2) Apply ephedrine, aminophylline or isoproterenol for nebulized inhalation. For patients with frequent purulent sputum, start applying antibacterial drugs 3 to 5 days before surgery and do postural drainage. (3) Patients with frequent asthma attacks may be given oral dexamethasone. (4) Give a small amount of medication before anesthesia. (5) Liver disease: Hepatitis and cirrhosis are common. Mild liver damage does not affect surgical tolerance; those with more severe liver damage or on the verge of decompensation have significantly weakened surgical tolerance and must undergo long and rigorous preparation before performing elective surgery; those with severe liver damage, manifesting obvious malnutrition, ascites, jaundice and coagulation dysfunction are generally not suitable for any surgery. Patients with acute hepatitis, except for emergency surgery, are not suitable for surgery. 6, kidney disease: all patients with kidney disease, should be kidney function tests, the degree of kidney function damage can be judged according to the 24-hour endogenous creatinine profile rate and blood urea nitrogen measurement value. It is divided into mild, moderate and severe. Mild and moderate renal function impairment can tolerate the surgery better after medical treatment; those with severe renal function impairment can still tolerate the surgery quite safely under the treatment of effective dialysis therapy. 7, adrenocortical insufficiency: except for patients with chronic adrenocortical insufficiency, anyone who is applying or has been treated with hormones for more than 1 to 2 weeks within 6 to 12 months can be given hydrocortisone before surgery, on the same day, or after surgery until the surgical stress has passed, then it can be discontinued. Diabetic patients with poor surgical tolerance should have proper blood glucose control, correction of fluid and acid-base balance imbalance, and improvement of nutritional status before surgery. Any surgery with the possibility of infection should use antibacterial drugs before surgery. Before performing major surgery, the patient’s blood sugar should be stabilized at normal or mildly elevated (5,6-11,2mmol/L), urine sugar +-++, and if the patient applies hypoglycemic drugs or long-acting insulin, it should be changed to short-acting insulin. Insulin can be given in the infusion in the ratio of 5:1 during and after surgery, and the postoperative insulin dosage can be given according to 4-6 hours urine glucose measurement.