Anorectal surgery generally requires local anesthesia, so what is local anesthesia?
1. Definition of local anesthesia:
Local anesthesia is also called local infiltration anesthesia. Anesthetics are injected into the vicinity of the operation area to block the anal nerves and make the nerve conduction function disappear. Anesthetics should also be injected into the sphincter to relax the sphincter and facilitate anesthesia. Since the perianal area is rich in nerve distribution, it is mainly distributed by the sensitive pudendal nerve branch, inferior hemorrhoidal nerve, anterior sphincter nerve, anal coccyx nerve and perineal branch of the fourth sacral nerve. Therefore, local anesthesia should be injected in a circle, especially on both sides and rear To stop completely. It is suitable for anal surgery with a small scope of operation, such as simple hemorrhoid ligation and resection, internal hemorrhoid injection, anal fissure resection, superficial anal fistula resection, and thrombus removal from external hemorrhoids. Commonly used local anesthetics are 0.5% procaine solution. In order to prolong the anesthesia time and slow down the absorption rate, add 3 to 5 drops of 1:1000 epinephrine to 100ml solution. Those who are allergic to procaine can switch to 0.5% lidocaine solution.
2. Operation steps:
The patient takes the bladder lithotomy position or the left decubitus position. After the perianal skin is disinfected, the four-point infiltration anesthesia method is often used, namely at the 3, 6, 9, 12 o'clock positions, at a distance of 1.0 to 1.5 cm from the anal edge. Do intradermal and subcutaneous infiltration, insert the needle vertically, insert the needle while injecting the medicine, then withdraw the needle to the subcutaneous, then change the direction, and inject clockwise or counterclockwise, that is, one injection point is injected in three directions, four points Anesthesia is injected in 12 directions. The depth of acupuncture is first into the subcutaneous layer of the external anal sphincter, the superficial and deep layers, and the left index finger is inserted into the rectum as a guide to prevent the needle tip from penetrating the intestinal wall. The depth is about 3cm and reaches the rectal submucosa. Such a tension creeping infiltration can achieve relaxation and anesthesia of the anal sphincter without causing edema and deformation of the anus.
3. Matters needing attention:
In local anesthesia, the poisoning and allergies of anesthetics should be prevented. The causes of poisoning include: injecting high-concentration and large-dose anesthetics or injecting anesthetics into the blood vessels within a short period of time; the patient has poor function or low tolerance to anesthetics, and is prone to poisoning, showing excitement or apathy, lethargy, pulse Too fast, the breathing deepens and accelerates, and the continued development may cause convulsions of the limbs, convulsions, and difficulty breathing. Once it occurs, stop anesthetics immediately, inhale oxygen, and intramuscularly inject phenobarbital sodium. For general convulsions, use thiopental sodium to stop convulsions; allergic reactions include urticaria, collapse, cyanosis, convulsions, and severe laryngeal edema and pulmonary edema. . If an allergic reaction is found, the use of local anesthetics should be stopped immediately, and anti-allergic and resuscitation treatment should be taken.