The incidence of anorectal diseases is high, and surgery is the most effective treatment in many cases. Specialized anesthesia, including inpatient surgery, ambulatory surgery and day surgery, has formed a subanesthetic specialty. I. Case selection Although anorectal diseases are chronic, some patients are often comorbid with serious medical diseases, therefore, adequate preoperative preparation and case selection are particularly important. Some comorbidities need attention: 1. Advanced age. Elderly people have increased dependence on their daily living environment, and it has been studied that elderly patients can be safely hospitalized for surgery, but there is an increased risk of intraoperative hemodynamic changes. 2, combined obstructive sleep apnea syndrome (OSA). ASA guidelines pointed out that: combined OSA surgery is generally mild degree of obstruction, less traumatic surgery or superficial surgery, postoperative does not require large doses of opioids to control pain; as far as possible, local anesthesia, regional block, sedative drugs need to be careful. 3, chronic obstructive pulmonary disease (COPD): COPD patients with perioperative pulmonary infection, congestive heart failure complications increased, preoperative smoking should be quit, infection control. 4, excessive obesity: obese people with hypertension, congestive heart failure is common, in addition to obese patients intraoperative and PACU stay during the respiratory complications increased. Second, anesthesia method There is no ideal anesthesia method for anorectal surgery so far. Anorectal neurovascular rich, complex nerve composition, anesthesia and postoperative analgesia requirements. Local anesthesia, regional block (CEB, SA, CEA, CSEA), general anesthesia, compound anesthesia can be applied to anorectal surgery, each method has its own advantages and disadvantages. 1, local anesthesia: local block by the physician, injection needle multi-point injection puncture point is located in the dentate line, fine injection needle, skilled injection pain can be reduced, and its success depends on the experience of the surgeon and the patient’s cooperation.Lohsiriwat V et al.] Simple perianal local infiltration of 222 cases of adult ambulatory anorectal surgery anesthesia is safe and effective, the incidence of urinary retention is low; Mariani P et al. 7.5mg /dl ropivacaine local anesthesia ambulatory 3-4 degrees ring hemorrhoidectomy, 96% of patients intraoperative VAS does not exceed 4, and no obvious adverse reactions; local anesthesia operation is simple, few postoperative complications, low cost, but the incidence of incomplete local infiltration block is high, and local infiltration caused by localized oedema of trauma on the surgical field and postoperative recovery has a certain impact. 2, regional block: according to the distribution of anorectal nerves, the scope of surgery is limited to the anus or perineum anesthesia plane up to L1-S5 can be; such as the scope of surgery up to the rectum and above, the plane needs to be up to T10 or more, otherwise the patient will have the intolerable lower abdominal distension caused by pulling and discomfort and emotional reaction. 3.Epidural anesthesia (CEA): The advantage of low level epidural anesthesia for anorectal surgery is that the catheter can be retained for epidural analgesia after surgery, but it increases the time of observation, which is suitable for hospitalized patients. China’s anorectal surgery using low-level epidural anesthesia is more, foreign data anorectal surgery with low-level epidural anesthesia is rare. Single epidural postoperative analgesia and sacral analgesia have similar effects. 4, lumbar anesthesia (SA): lumbar anesthesia (or saddle anesthesia) is widely used in rectal and anal surgery. Lumbar anesthesia has the advantages of fast onset, easy to accept, small cost, small caliber, pen-point puncture needle application, lumbar anesthesia after puncture headache (PDPH) incidence decreased to only 0-2%. Although lumbar anesthesia has the occurrence of transient nerve stimulation syndrome (TNS), but lidocaine and bupivacaine is still the most commonly used local anesthetic. Extensive lower limb block, abnormally high and hypotensive planes, bradycardia, postoperative headache, urinary retention and other complications of lumbar anesthesia result in prolonged stay and delayed discharge from the hospital, and saddle anesthesia also carries the risk of rising planes when the seated position is changed, thus limiting its use.The first case of transient nerve root irritation (TRI) induced by lidocaine was reported in 1993, and a meta-analysis of 1,437 lumbar anesthesia patients was conducted by Zaric D et al. , of whom 120 developed TNS (8.35%), and lidocaine was 7.16 times more potent than other local anesthetics. High concentrations of lidocaine heavy weight solutions limit use. Recently, the trend in lumbar anesthesia for anorectal surgery has been to reduce the dose of local anesthetics and explore the lowest effective dose. Smaller doses of heavy gravity and light gravity lidocaine, bupivacaine, and ropivacaine for elective lumbar anesthesia for ambulatory anorectal surgery are beginning to be used. Reducing the dose of lidocaine, compounded with 10-25 micrograms of fentanyl intrathecally not only results in faster recovery but also reduces complications and adverse effects.Gudaityte J et al. concluded that the appropriate dose for lumbar anesthesia of 0.5% heavy gravity bupivacaine for anorectal surgery in adults is 4-5 mg and 7.5 mg results in excessively prolonged sensory and motor blockade. Small dose bupivacaine lumbar anesthesia in anorectal surgery, 0.3% bupivacaine 1.4 ml can meet the needs of the operation, with few adverse effects. Small dose ropivacaine lumbar anesthesia in anorectal surgery, that 0.375% heavy weight ropivacaine 7.5mg lumbar anesthesia can meet the needs of anorectal surgery, circulatory stabilization, light motor block, less urinary retention.Huang HW et al. compared the volume of 3mg and 6mg butylcarbamate (containing epinephrine) lumbar anesthesia for anorectal surgery, the plane of 3mg is T12, the plane of 6mg is T9; that can be for the adequate anesthesia for anorectal surgery. Moreover, 3mg can significantly reduce the incidence of bradycardia, and also have a tendency to reduce the occurrence of hypotension. 5, sacral anesthesia (CEB): sacral anesthesia anal sphincter relaxation is good, the block range is small, the lower limb block is light, the postoperative recovery is fast, the complication is less, the respiratory circulation influence is slight, and there is good postoperative analgesia. A single sacral block can meet the needs of anorectal surgery. Sacral block is widely used for ambulatory surgery and postoperative analgesia in children. Due to the high rate of variability in adults with acquired effects; its failure rate ranges from 12.5% -1%, which, in addition to the variability factor, is directly related to the skill level of the anesthesiologist. The application of modified sacral anesthesia has greatly improved its success rate. Recently sacral block has been used in adult anorectal surgery with more reports. Sacral block has gradually become the first choice of anesthesia for anorectal surgery.Silvani P et al. observed that in children, after the induction of general anesthesia, high volume, low concentration (0.1%, 1.8 ml/kg) or low volume, high concentration (0.375%, 0.5 ml/kg) ropivacaine sacral block was performed, and during the operation, analgesia was adequate in both groups, but the high volume, low concentration group had a longer duration of postoperative analgesia than the low volume, high concentration group (average 952min). (Wong SY et al. 1.5% lidocaine 20ml outpatient adult gynecological perineal minor surgery, 4.1% failure rate, the average plane T10, PACU stay an average of 74.30 minutes, does not prolong the time of discharge. 6, general anesthesia (GA): general anesthesia for anorectal surgery is a frequently used method, especially for children. In recent years rapid onset of action, short half-life, non-accumulation, controllable, small adverse effects of sedative drugs, anesthetics, muscle relaxants are widely used in surgical anesthesia. Propofol has a rapid onset of action, high quality of awakening, and inhibits nausea and vomiting; the inhalation anesthetic sevoflurane and desflurane have a low blood-gas partition coefficient; and then compounded with the short-acting analgesic remifentanil and alfentanil target-controlled infusion has been rapidly popularized for anal and intestinal ambulatory surgery [18]. The proper use of short-acting and long-acting can reduce the adverse effects do not affect the early discharge from the hospital. The downside is that these drugs are still relatively expensive. Short anorectal surgery general anesthesia with a laryngeal mask or oropharyngeal airway with a sleeve instead of tracheal intubation, intraoperative BIS to monitor the depth of anesthesia, can reduce the amount of general anesthesia, to avoid the use of inotropic and antagonistic drugs. 7, compound anesthesia: local anesthesia often compound MAC; regional block adult often compound intravenous sedation, children more compound general anesthesia, lumbar and hard joint anesthesia has also been reported.Inselmo PM and other studies found that children bupivacaine sacral block compound general anesthesia sevoflurane faster than the onset of propofol effect.Kokinsky E that children non-sacral anesthesia compound intravenous fentanyl does not increase the effect of effective analgesia, but the side effects of nausea, vomiting Increased. Adult anorectal surgery sacral anesthesia compound intravenous sedation anesthesia effect is good, less adverse effects.Sun MY et al. review 448 cases of ambulatory prone position anorectal surgery local anesthesia compounded propofol and ketamine deep sedation is safe and effective, reduce the use of the PACU, as early as possible to leave the hospital.Dalal PG et al. 3 months follow-up found that children ketamine general anesthesia after anorectal surgery, nightmares, awakening, and other behavioral reactions are common, the compound midazolam and propofol significantly prevented ketamine-related abnormal behavioral reactions; the disadvantage was prolonged wakefulness and PACU stay. Third, the prevention and control of complications Preventing or reducing the occurrence of postoperative complications plays a crucial role in the early discharge of anal surgery, and serious complications cause delayed discharge or readmission. Postoperative bleeding, pain, nausea and vomiting, and urinary retention are the main causes of re-admission for anorectal surgery. 1, Bleeding: most data show that the proportion of postoperative bleeding, although very low, but forced the patient to have to be readmitted to the hospital. Stopping anticoagulants one week before surgery, careful hemostasis by surgeons, local hemostatic dressings or application of hemostatic drugs have a certain preventive effect on postoperative bleeding. 2, nausea and vomiting: high incidence of nausea and vomiting after anal and intestinal surgery. Intestinal surgery itself is prone to postoperative nausea and vomiting; anesthesia after eating too early can cause nausea and vomiting; postoperative severe pain itself will cause nausea and vomiting; a regular dose of opioids may cause nausea and vomiting, the rational application of opioids and early prevention of nausea and vomiting is essential.Khalil SN et al. study of children’s bupivacaine, ropivacaine sacral block plus halothane, laughing gas shallow general anesthesia and avoidance of narcotic analgesics reduced the incidence of PONV. A large number of data show that the preventive application of haloperidol, ondansetron, dexamethasone and other postoperative nausea and vomiting have a better effect. 3, postoperative pain: the goal of controlling pain after anal surgery is to provide good postoperative analgesia with few side effects. Multimodal balanced analgesia is often used. Regional anesthesia techniques are useful for analgesia in ambulatory surgery.Tsui BC et al. reviewed and analyzed the progress of sacral analgesia in children and concluded that intra-sacral injection of opioids is satisfactory for analgesia in children undergoing ambulatory surgery with some unwanted side effects; Van Elstraete AC et al. used intra-sacral injection of colistin for postoperative analgesia after anorectal surgery in adults. In addition preoperative pre-analgesia and postoperative oral nonsteroidal analgesic anti-inflammatory drugs are a commonly used option. 4, urinary retention: is a common complication after anorectal surgery. The main reasons are: the influence of anesthesia, the elderly, postoperative pain, unaccustomed to bed urination, etc. Pertek J.P. believes that the incidence of urinary retention has nothing to do with the method of anesthesia. It is generally believed that the use of opioids, especially intrathecal or epidural administration, aggravates the occurrence of urinary retention; long-acting local anesthetics have a higher incidence than short-acting local anesthetics; and the incidence is higher in those who have prostatic disease.Toyonaga T et al. found that: perioperative increase in the amount of fluid infusion, postoperative pain are independent risk factors for postoperative urinary retention. Preoperative treatment of urinary tract disease; preoperative emptying of the bladder; limiting the amount of fluids before the first postoperative urination and early mobilization can improve the occurrence of urinary retention. The majority of patients need to stay in the anesthesia recovery room for a period of time after surgery to be sent back to the inpatient area. Ambulatory or day surgery discharge criteria is to determine whether the patient can be discharged from the hospital safety indicators, general anesthesia recovery to the vital signs are stable, conscious, free movement, no obvious dizziness, nausea, pain, bleeding, etc. can be discharged. There are five discharge criteria described as: four “A”, fully awake (awake), freedom of movement (ambulation), normal feeding (alimentation), analgesia (analgesia) urination is positive (micturition).Coloma M et al study concluded that a single dose of 4mg dexamethasone reduced the time of discharge from anal surgery. V. Conclusion The ideal anesthesia for anorectal surgery requires fast onset of action and postoperative recovery, good sedation (or sleep), sphincter relaxation, intraoperative analgesia, satisfactory postoperative pain control, easy control of anesthesia, fewer intra-operative and postoperative adverse reactions, and no delay in hospital discharge or readmission. Various anesthesia methods have their own advantages and disadvantages. With the application of new anesthetics, the improvement of technology of traditional anesthesia methods, the accumulation of experience, and the further rationalization of the management mode and process, it provides a broad prospect for the surgical treatment of anorectal diseases.