(1) Surface anesthesia The local anesthetic with strong penetrability is applied to the mucosal surface so that it penetrates the mucosa and blocks its superficial nerves without causing mucosal anesthesia. For superficial surgery or examination of the eyes, nose, mouth, throat, trachea, urethra, etc. The method is a little drip, coating, spraying, infusion, and the like. The commonly used drug is 0.5~1% tetracaine, the second limit is 40 mg, 2% lidocaine, and the limit is 200 mg. Because the mucous membrane is rich in blood, the drug can be quickly absorbed and easily poisoned, so the dose of the surface anesthetic should be reduced to 1/4 to 1 / 2 of the maximum dose of the infiltrated anesthetic.
(2) Local infiltration anesthesia The local anesthetic is injected into each layer of the surgical site to cause conduction block at the nerve ending, which is called local infiltration anesthesia. The method is to first inject a skin hill into the skin incision, and then make a series of skin hills along the direction of the incision. When the new skin is used, the needle should be inserted in the former skin, so the local acupuncture only has the first acupuncture. There is a pain when entering, this is a needle technique (Figure 1- 23). Then, the stratified injection, that is, the ridged surface expands the infiltration range to the surrounding and deep parts according to the anatomical level. When injecting a large amount of anesthetic, a large amount of anesthetic should be injected in a short period of time, so that the anesthetic produces a water pressure in the tissue, which is a tension infiltration. Therefore, the anesthetic can not be widely and uniformly contacted with the nerve, so that the anesthetic effect is more Enhanced. Syringe the syringe before each injection to avoid accidental injection into the blood vessel. Commonly used 0. 5~1% procaine, - the total amount does not exceed 1 gram.