There is no quality problem. Tetanus antitoxin itself is a heterogeneous protein and an allergen of human body. In addition, the hospital did not do skin tests according to the instructions, so false positive skin tests often appeared, but it would be fine if the needles were filled. There will be 99% false positive in clinic. You can give a paper a look: the causes and countermeasures of false positive skin test of tetanus antitoxin Hu Fenghua (Tianjin First Central Hospital, Tianjin 300 192) Keywords tetanus antitoxin; Skin test; False Positive China Library ClassificationNo. R472 Document IdentificationNo. B1006.9143 (2009) 02-0122-02 Tetanus Antitoxin (TAT) is a liquid preparation prepared by digesting the serum of horses immunized with tetanus toxoid with stomach enzyme, which is an exogenous protein for human body. . At present, the anti-tetanus immunoglobulin preparation derived from human blood has a good effect and can avoid allergic reaction, but it has few sources and complicated preparation, so TAT is still the main biological product for preventing and treating tetanus. The traditional skin test method has a high false positive rate, and the desensitization injection method is cumbersome and time-consuming. Therefore, in recent years, nursing colleagues have analyzed various possible factors that cause false positive TAT skin test, conducted a lot of clinical practice and research, and found out the corresponding countermeasures. The research progress is summarized as follows. 1 Causes of false positive of tetanus antitoxin skin test (TAT) 1 Improper storage. Clinical tetanus antitoxin exists when stored at room temperature. TAT is a horse serum product, which is prepared by immunizing horses with toxoid. TAT belongs to foreign protein, which is easy to deteriorate at room temperature. Improper selection of diluent when preparing 1.2 mouse skin test solution. Some hospitals also use water for injection to prepare various skin test solutions. Because the water for injection is hypotonic, subcutaneous injection can make subcutaneous tissue cells swell, cause local pain, irritate the skin, cause local congestion and flushing, and cause false positive. 1.3 concentration skin test solution The preparation method of traditional skin test solution takes 0. 1 ml TAT stock solution (specification 15 OOU/ ml); 0Z physiological saline diluted to 1mL (including ~ 5ou) is the skin test solution, that is, o. 1mL TAT skin test solution containing 15U. The concentration and dosage of TAT skin test solution are directly proportional to the degree of local reaction. The high concentration of TAT skin test solution enhanced the degree of local reaction. After local skin receives high concentration of macromolecular foreign protein, it causes the osmotic pressure of tissue to increase and local skin reaction. 1.4 The preparation of skin test solution is inaccurate. The commonly used syringe for preparing TAT skin test solution is 1mL disposable sterile plastic syringe, and the dead cavity factor of syringe is the main reason for the increase of skin test solution concentration. The dead space of syringe includes three parts, namely, the inner space of nipple, the space between nipple and needle bolt and the space of needle bar. After years of repeated observation on the dose of tetanus antitoxin stock solution, it was found that the dose of tetanus antitoxin injection produced by various manufacturers was less than 1mL, ranging from 0.8 ml to 0.5 ml. The preparation of skin test solution according to the method required by textbooks leads to the high concentration of TAT skin test solution and the increase of false positive rate of TAT skin test. About the author: Hu Fenghua (1969. ), female, is the nurse in charge. When a certain amount of tetanus antitoxin is inhaled in the syringe, due to the suction of the syringe, the diluent enters the syringe with a certain impulse, which strongly stirs the tetanus antitoxin in the tube, thus leading to the generation of foam and affecting the dosage of the liquid medicine. 1.5 improper use of disinfectant In clinic, 75% alcohol is often used to disinfect local skin before skin test. When observing the results, it was found that some patients had localized flushing in the skin test area, which was consistent with the size of the alcohol disinfection area, and the diameter was about 5cm, which was just the disinfection range. It was impossible to judge whether it was alcohol allergy or 1IAT allergy. This brings great difficulty to the judgment of skin test results, thus increasing the false positive rate of TAT skin test. 1.6 if the needle is not properly selected for intradermal injection, choose the No.5 or No.6.5 needle. Because the needle diameter is very irritating to the local area, it is prone to skin stress reactions such as elevation and redness, which increases the false positive rate of TAT skin test. 1.7 Incorrect needle insertion method During intradermal injection, the needle insertion direction is perpendicular to the forearm striated muscle, which causes mechanical damage to the skin, and the resistance of the liquid medicine to countercurrent is large, which is easy to produce tearing pain, and local pain will cause false positive reaction. This is due to improper operation, which increases the pain of patients and the stimulation to local skin, leading to an increase in the false positive rate of TAT skin test. 1.8 The observation time of traditional skin test is too short. Clinical observation showed that TAT skin test reaction was the strongest after 15 minutes. Therefore, the observation time of traditional skin test for 20 minutes is too short, and the false positive rate is the highest. 1.9 The judgment standard of traditional skin test results is too simple. Basic Nursing, the textbook of national secondary health schools, the third edition, the negative judgment standard of tetanus antitoxin intradermal test results: local no redness and swelling. Positive: The local reaction is elevation swelling, induration with diameter larger than 1.5cm, sometimes pseudopodia, complaining of itching or other allergic symptoms. Pang,,, etc. Through the comparative observation of 1260 cases of clinical operation, the results showed that 8 cases were negative according to the conventional standard, which was less than 1%, that is to say, more than 99% of the patients' skin test reactions exceeded the original negative range, and the positive rate was very high. 1. 10d, JL's special physiological characteristics d, JL's skin is thin and blood vessels are rich, so it is easy to spread after injection, with a large blush range and a small pitch. If the operation is not gentle enough, the skin is too tight, the hands are caught and pinched, and the sleeves are rubbed. The range of blush can be expanded. Then there is the lack of language expression ability of infants and young children, and some positive manifestations, such as itching and chest tightness, cannot be accurately expressed, which affects the tester's judgment results. RjanjinJoumalofNursing, April 2009, Vo 1. 17+07, No.2 123 is easy to cause false positive in TAT skin test, thus increasing the false positive rate of TAT skin test. 1. 1 1 Other reasons. Due to the weak sense of responsibility of nursing staff, some allergy testers observed the reaction in less than 20 minutes. If they observed it in advance, they would see that the flush caused by the injection on the skin had not subsided and mistakenly thought that the skin test was positive. Some allergy testers are afraid of TAT allergic reaction, which leads to the lack of strict judgment criteria, and does not follow the positive judgment criteria of skin test, which leads to the increase of false positive rate of TAT skin test. Some patients feel abnormal due to the influence of fear, mental stress or disease and pain stimulation, and complain of itching or pain during skin test, which is misjudged as false positive of TAT skin test. 2 countermeasures 2. proper management of1tat preparation I'AT preparation should be kept at 2-8. C in the dark, too high or too low temperature will affect the efficacy. Careful inspection before injection shows that the preparation is turbid and unshakable, foreign matter or ampoule is broken, the label is unclear, and it is invalid after expiration, so it is not allowed to be used. Prevent the preparation from deteriorating and affect the accuracy of skin test. 2.2 When selecting a suitable diluent to prepare TAT skin test solution, physiological saline should be selected as the solvent. Because it is isotonic fluid, its osmotic pressure is equal to that of tissue fluid, which has little stimulation to skin and tissue and reduces the false positive rate of TAT skin test. 2.3 Promote the use of 7.5 IU as the standard concentration of skin test. In the past, TAT skin test was based on the textbook l5IU. At present, the skin test solution with 7.5 IU as the standard and 7.5 IU as the standard in medicine can more accurately reflect the yin and yang results of patients. It can not only avoid missed diagnosis caused by false negative, but also reduce false positive and shorten treatment time. Intradermal injection of TAT 0. 1 ml containing 7.5U is the best dosage and the best concentration is 75U/ml. The application of this skin test solution can not only alleviate the pain of patients, but also reduce the workload of nurses. Moreover, the preparation method of skin test solution is simple and easy for nurses to master. 2.4 Improved preparation method Huang Xiuhua et al. determined that the residual amount in the dead space of the syringe was 0.06 ",which should be subtracted when preparing the skin test solution. 1mL disposable insulin syringe has almost no dead angle and is an ideal syringe for preparing skin test solution. When preparing the skin test solution, since the tetanus antitoxin injection produced by various manufacturers is less than 1mL, when preparing the TAT skin test solution, the amount of 1500IU of each preparation is diluted with an appropriate amount of normal saline. Tetanus antitoxin injection is a biological product made by ammonium sulfate salting out method, and it is a polymer compound solution of surface active substances. When preparing, first extract 0. 1ml physiological saline, then extract 0. 1ml TAT, which will accelerate the dilution and dissolution of antitoxin without foaming, then extract 0.8mL physiological saline to prepare 150IU/MLC "J, and then discharge 0.5mL ~ =/Ju physiological saline, that is, the prepared skin test solution is 2.5 It is safer and more reliable to disinfect the skin at the injection site with a 75% alcohol cotton swab (centered on the injection point, with a diameter greater than 5cm), and then wipe the skin at the injection site with a physiological saline cotton swab (the method is the same as alcohol disinfection, but the diameter is less than 5cm, wiping 1 time) for TAT skin test, which can reduce the positive rate of TAT skin test. 2.6 Choose appropriate intradermal injection needles, and choose No.4 and No.4.5 needles. Because the stimulation to the local skin is reduced when the needle is inserted into the small skin, the patient has no tearing pain or only slight pain, and the stress response of the skin is reduced. 2.7 Improve the needle insertion method during intradermal injection. During the skin test, the needle was inserted in three horizontal directions parallel to the wrist skin on the transverse striation of the forearm of the patient, so it was the part with the least distal distribution of the cutaneous branches of ulnar nerve and radial nerve. When the needle is inserted parallel to the dermatoglyphics, the dermatoglyphics move forward with little mechanical damage, and the dermatoglyphics are not broken, and the downstream resistance of the liquid medicine is small, which reduces the stimulation of the skin test solution to local skin, thus reducing the false positive rate of TAT skin test. 2.8 The best observation time of skin test results is 30min7. For patients with suspected false positive reaction, physiological saline can be used as control and desensitization treatment according to the specific situation, focusing on "local" or "whole body itching", "pitching" and "pitching texture and shape", and adopting "delayed observation method" and "crowd prevention observation method" to improve the accuracy of judgment. Skin test ruddy is common and has no specific significance, and can only be used as evidence of TAT allergic reaction. 2.9 Skin test results Judging from the standard skin test results, there is no redness and swelling in the negative part, induration does not exceed 1eln, and there is no reaction in the whole body and other parts. Cui Shuming uses (+) (++) to indicate the positive classification, such as table 1(+,++is false positive,++is positive,++is strong positive). Judging by this method, the false positive rate is obviously reduced. 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