Best practice & research. Clinical anaesthesiology
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Best Pract Res Clin Anaesthesiol · Dec 2002
ReviewEpidural and intrathecal analgesia for cancer pain.
The three-step analgesic ladder approach developed by the World Health Organization works well in treating the vast majority (70-90%) of patients suffering from pain related to cancer. In those patients who do not get pain relief by this three-step approach, intraspinal agents can be a fourth step in managing pain of malignant origin. ⋯ Many non-opioid agents have also been used intraspinally either alone or in combination with opioids in the treatment of intractable cancer pain. This chapter summarizes the clinical use of these agents with some practical points.
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Systemic administration of analgesic drugs is still the most widely used method for providing pain relief in acute painful situations. Opioids may be selected on the basis of their physicochemical characteristics and their diffusion index to the brain. But in clinical practice, their very steep concentration-analgesic effect relationship remains a critical aspect of opioid therapy. ⋯ CSIs may be beneficial in patients in whom post-operative bleeding is a major surgical risk as the effects of NSAIDs on coagulation may last for days. Finally, low-dose ketamine infusions remain a worthwhile addition to opioid therapy. Analgesic concentrations of ketamine are 1/5th to 1/10th the anaesthetic concentration and exert significant inhibition on N-methyl-d-aspartate (NMDA) receptor activation.
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Best Pract Res Clin Anaesthesiol · Dec 2002
ReviewEffect of post-operative analgesia on patient morbidity.
The pathophysiology that commonly follows surgery results in detrimental physiological effects and may be associated with post-operative mortality and morbidity. The use of post-operative epidural analgesia, but not systemic opioids, may attenuate some of these adverse physiological effects and result in a decrease in patient-related morbidity post-operatively. Randomized trials suggest that the perioperative use of epidural analgesia may facilitate return of gastrointestinal function, attenuate hypercoagulable events and diminish post-operative pulmonary complications. A multimodal approach incorporating the use of epidural analgesia to control perioperative pathophysiology will facilitate the patient's recovery.
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Diagnostic blocks are used to obtain information about the source of a patient's pain. As such they differ in principle and in practice from regional anaesthetic blocks. In order to be valid, diagnostic blocks must be precise and target-specific. ⋯ This warns that sympathetic blocks must be controlled in each and every case lest false conclusions be drawn about the response. Medial branch blocks of the lumbar and of the cervical dorsal rami have been extensively investigated in order to establish their validity, diagnostic utility and therapeutic utility. They provide an example and benchmark for how diagnostic blocks can and should be validated.
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To implement a successful acute pain service the following factors are the most important for success: anaesthesiologist-supervised pain nurses and an ongoing educational programme for patients and all health personnel involved in the care of surgical patients. The benefits in increased patient satisfaction and improved outcome after surgery will far outweigh the costs of running an acute pain service that raises standards of pain management throughout the hospital. Optimal use of basic pharmacological analgesia will improve relief of post-operative pain for most surgical patients. ⋯ Chronic pain is common after surgery. Better acute pain relief may reduce this distressing long-term complication of surgery. Research into the long-term effects of optimal neuraxial analgesia and drugs that dampen glutamatergic hyperphenomena (hyperalgesia/allodynia) are urgently needed to verify whether these approaches can reduce the problem of intractable chronic post-operative pain.