Cerebrospinal fluid tryptophan test

The mixture of cerebrospinal fluid, concentrated hydrochloric acid and formaldehyde is positive with the purple ring at the contact with the sodium nitrite solution; if there is a brownish yellow ring or a ring with no color at all, it is negative. The positive rate of this test is about 90% in tuberculous meningitis, but it is not specific. In epidemic encephalitis, the positive rate of the tryptophan test was only 15%. Nevertheless, this test can be used as a powerful reference for the diagnosis of tuberculous meningitis. It should be noted that this test can also show a positive reaction when the cerebrospinal fluid contains pus, blood or yellowing. Basic Information Specialist classification: examination classification: cerebrospinal fluid examination Applicable gender: whether men and women apply fasting: fasting Analysis results: Below normal: Normal value: no Above normal: negative: normal. Positive: Positive: tuberculous encephalitis (clear and colorless), cerebrospinal fluid containing pus or blood. Tips: The examinee should stop taking epinephrine, isoproterenol, meperidine, nicotine, aspirin and other drugs, and maintain a reasonable diet and rest. Normal value negative. Clinical significance Abnormal result Positive: tuberculous encephalitis (clear and colorless), cerebrospinal fluid containing pus or blood. People who need to be tested High fever, stiff neck, severe headache, loss of appetite, unconsciousness, vomiting, convulsions, burnout, sleepiness, sensitivity to light, small blood spots on the skin, skin rash symptoms. Positive results may be diseases: tuberculous meningitis considerations Before the test: The examinee should stop taking epinephrine, isoproterenol, pethidine, nicotine, aspirin and other drugs, and maintain a reasonable diet and rest. When checking: Eliminate the anxiety and anxiety. Inspection process 1. The patient lies on the hard board bed, the back is perpendicular to the table top, the head is bent as far as possible to the chest, the knees are tightly attached to the abdomen with both hands, so that the trunk is as arched as possible; or the assistant is used to hold the patient's head opposite the surgeon. The other hand pulls the lower limbs of the armpits and holds them tightly, so that the spine is as convex as possible to widen the intervertebral space, which is convenient for needle insertion. 2, determine the puncture point, usually the junction point of the highest point of the bilateral iliac spine and the posterior median line as the puncture point, here is equivalent to the third to fourth lumbar spine process, sometimes in the upper or lower lumbar spine The gap is carried out. 3, routine disinfection of the skin after wearing sterile gloves, cover the hole towel, with 2% lidocaine from the skin to the interspinous ligament for layer-by-layer local anesthesia. 4, the surgeon uses the left hand to fix the puncture point skin, the right hand holding puncture needle to the vertical back, the needle tip slightly obliquely to the direction of the head, the adult needle depth is about 4 ~ 6cm, children about 2 ~ 4cm. When the needle passes through the ligament and the dura mater, there is a sudden loss of resistance. At this point, the needle core can be slowly withdrawn (to prevent the cerebrospinal fluid from flowing out quickly, causing cerebral palsy), and the cerebrospinal fluid can be seen to flow out. 5. Connect the pressure measuring tube to measure the pressure before draining. The cerebrospinal fluid pressure in the normal lateral position is 70-180 mmH2O (0.098 Kpa=10 mmH2O) or 40-50 d/min. If you continue to do the queckstedt test, you can see if there is any obstruction in the subarachnoid space. That is, after the initial pressure is measured, the assistant first compresses one side of the carotid artery for about 10 s, then presses the other side, and finally presses both sides of the carotid artery. When the carotid artery is compressed at normal time, the pressure of the cerebrospinal fluid immediately increases by about one time, and after 10 to 20 seconds after the pressure is released, it rapidly drops to the original level, which is called negative in the obstruction test, indicating that the subarachnoid space is unobstructed; if the carotid artery is compressed, it cannot be When the pressure of the cerebrospinal fluid is raised, the obstruction test is positive, indicating that the subarachnoid space is completely blocked. If it rises slowly after applying pressure, it will slowly fall after relaxation, indicating incomplete obstruction. but. Those with increased intracranial pressure are forbidden to do this test. 6. Remove the pressure measuring tube and collect 2~5ml of cerebrospinal fluid for examination. If it is needed for cultivation, use sterile tube to keep the specimen. 7. After the operation, insert the needle core and pull out the puncture needle together, cover the sterile gauze, and fix it with tape. 8, go to the pillow for 4 to 6 hours, so as not to cause postoperative low intracranial pressure headache. Not suitable for the crowd 1. If there is obvious papilledema or cerebral palsy, contraindications are contraindicated. 2. Patients who are in shock, exhaustion or endangered state and local skin inflammation, and lesions in the posterior cranial fossa are contraindicated. Adverse reactions and risks If the patient has symptoms such as breathing, pulse, or abnormal color during puncture, stop the operation immediately and deal with it accordingly.

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