I. Definition and classification of cancer pain
Cancer pain refers to the pain directly caused by cancer or cancer-related lesions and anti-cancer treatment. Cancer pain is often chronic and is a common symptom of cancer patients.
The direct causes of cancer pain can be divided into three main categories:
1.Somatic pain: bone metastasis
2. Visceral pain: pain caused by invasion, compression, pulling and pressure increase of visceral tumor
3.Nerve pain: such as pain caused by tumor invasion to the arm or lumbar plexus.
Current situation of cancer pain
According to the survey of World Health Organization, there are 10 million new cancer patients in the world every year, and 30% to 50% of these patients have different degrees of pain. The pain treatment committee of the Chinese Medical Association Anesthesiology Branch announced that 51%-62% of the 7 million cancer patients in China have different degrees of pain, and 30% of them have unbearable and severe pain.
III. Principles of drug treatment for cancer pain
Drug analgesic treatment is the main treatment method for cancer pain, and the ideal control of cancer pain needs to follow the WHO three-step analgesic principle.
1.Orally administered drugs.
Advantages: simple, economic and convenient; regular absorption of drugs, easy to control the dose; precise efficacy and high safety; easy to adjust the dose; when oral opioids are taken, the absorption is slow, especially oral controlled-release morphine blood concentration is smooth and the peak is low, which does not produce euphoria and is not easy to produce addiction and drug dependence.
2.Take the drug on time.
According to the half-life of the drug and the time of action, the drug is given regularly. To ensure that the next dose should be given before the pain-relieving effect of the previous dose disappears.
3. Give the drug according to the step
If the patient is already in severe pain at the time of consultation, he should use severe analgesics directly. The first and second step drugs have a maximum limit of analgesic effect when they are used, i.e. there is a ceiling effect. Therefore, after the regular use of first and second-order drugs, if the pain cannot be controlled, the dosage should not be increased, switched or combined with analgesic drugs of the same order, and a higher-order analgesic drug should be chosen.
If the regular dose of pain control is not effective, the dose of morphine can be gradually increased until the pain is completely controlled, instead of using several drugs in rotation or adding another similar drug.
4.Dose individualization
The pain threshold and sensitivity to narcotic analgesic drugs vary greatly among patients; the same patient’s pain level also changes in different stages of cancer, so there is no standard amount of opioid drugs; the clinic should always increase or decrease and adjust the dose of analgesic drugs according to the patient’s pain condition, and any dose that can relieve pain is the correct dose.
Fourth, opioid treatment of adverse reactions to deal with
1, the principle of handling constipation:
Give laxatives in advance: hemp nut lozenges, fruit guide tablets, rhubarb soda, lactulose, poo nai tong, etc.. Can also be given along with the whole. In addition, can apply senna for indirect impact.
2.The principle of handling nausea and vomiting
Opioids should be applied in small doses and antiemetics should be given in advance before using opioids. 30-50% of patients may have nausea and vomiting in the first 2-3 days,
However, after 3-5 days, it will be tolerated, so that patients can be prepared. Severe nausea and vomiting after two weeks of medication should not be related to opioids.
3.Treatment of urinary retention
Induction by running water, hot water in the perineum, and massage in the bladder area can be used to promote urination. If the effect is not good, the catheter can be left in place, but the retention time should not be too long, usually not more than a week, to avoid urinary tract infection.
4.Over-sedation
Clinical manifestations: sleepiness and drowsiness. Therefore, the drug should start with a small dose and gradually increase the dose. When excessive sedation occurs, reduce the drug dose, also can add stimulants, such as taking coffee, strong tea, if necessary, can be slowly pushed through the vein naloxone.
5.Respiratory depression
General oral opioids rarely occur respiratory depression. The principles of rescue treatment for respiratory depression are as follows: establish a clear airway, assist or control ventilation; respiratory resuscitation; use opioid antagonists.
V. New advances in cancer pain treatment
The pain of some patients with advanced cancer pain is so stubborn that even after the analgesia of the three steps of drugs, the pain still cannot be effectively controlled, and some patients cannot be effectively analgesic according to the three-step analgesic program because they cannot tolerate the side effects of opioids. The main minimally invasive surgical treatments in pain department include nerve block and destruction, spinal cord electrical stimulation therapy, and programmable morphine pump implantation techniques, which are accepted by the majority of cancer pain patients for their better efficacy, smaller drug doses, and minimal side effects. With the improvement of people’s demand for quality of life and the society’s emphasis on cancer pain, many domestic hospitals’ pain departments have standardized cancer pain wards, which are very helpful to improve the quality of life of patients with advanced tumor and increase their survival rate.