I. Three-step treatment of drugs First step: non-opioid analgesics, mainly non-steroidal anti-inflammatory analgesics, such as aspirin, anti-inflammatory pain, etc. Second ladder: weak opioid drugs, such as codeine, chimantin, etc. Third order: strong opioids, such as morphine, oxycodone, etc. Drug therapy, especially oral drug therapy, is an important approach in pain management, and others include transdermal patches and intravenous administration. Rational and comprehensive pharmacological treatment can provide pain relief for most patients. However, 10-20% of patients with intractable pain do not respond well to these delivery methods and require interventional therapy. And the use of high doses of analgesic drugs can produce serious and intolerable side effects, such as nausea and vomiting, nephrotoxicity, neuropsychotoxicity such as drowsiness and delirium, which hinder the application of traditional route drugs. Nerve destructive therapy Nerve destructive therapy is effective for pain caused by tumor invasion of nerves, but because cancer pain is not simply caused by invasion of nerves, and because pain caused by tumor metastasis is generally diffuse, therefore, nerve destructive therapy alone is not effective, and often needs to be used together with drugs. Epidural drug delivery therapy reduces the amount of drugs and is more effective for pain in limited areas. However, because the epidural drug diffusion is relatively limited, the effect on a wide range of pain may not be particularly satisfactory, and the epidural catheter is easily blocked, which also limits the further application of epidural drug delivery. Intrathecal drug infusion therapy Intrathecal drug infusion therapy injects drugs directly into the subarachnoid space and acts on the corresponding sites of the spinal cord, thus greatly reducing the amount of drugs. Take morphine as an example, if the patient takes 300mg of morphine orally every day, only 1mg is needed intrathecally. Because the dosage of the drug is greatly reduced, the side effects are fewer and milder, and even if they occur, they disappear quickly after a short period of adaptation. SynchroMed intrathecal infusion system has a very precise flow rate, the lowest flow rate of the pumps currently used in China can reach 0.048ml/day, and there are various adjustable modes, which can be given to different infusion modes according to the patient’s pain condition, so as to achieve the maximum pain relief with the minimum amount of medicine. It is a fully implantable programmable computerized infusion pump in the true sense of the word, as it can be adjusted outside the body with a programmable controller. The disadvantage of intrathecal drug infusion therapy is that it is more expensive and requires replacement of the subcutaneous implanted drug pump after about 6-7 years of use.