[Postoperative pain.].
A short survey about the different methods available for producing postoperative analgesia is given, the goal being to make it clear to the clinician that there are quite a number of techniques to be used although the everyday clinical practice often sticks to simple and not too effective methods of pain treatment following surgery. Initially presenting short informations about the neurophysiology of pain and the pathogenesis and causes of postoperative pain two main groups of producing analgesia are then discussed.Thefirst group deals with the systemic use of analgesics be it nonnarcotic analgesic antipyretics or narcotic analgesics (opioids). As for the first subgroup the peripheral action of these drugs (metamizol, acetylsalicylic acid, paracetamol) is brought about by blocking the synthesis of prostaglandins. These substances can only be used for very moderate postoperative pain f.i. following head and neck surgery. The strong acting opioids belong to the second subgroup. Recent informations on receptor sites in the brain and cord and the subgrouping of the receptors throws new light on the understanding of the different effects of these drugs and on the pathomechanisms of agonistic, antagonistic and mixed activities. The clinically used opioids then are mentioned (morphine, fentanyl, methadon, pethidin, piritramide, tilidin, buprenorphin and pentazocine) and dosage, duration of action, antagonisms and untoward side effects are presented. Stress is laid on the recent development of patient-controlled analgesia with all its advantages. Thesecond main group of methods for postoperative analgesia consists of regional anesthesia techniques as there are brachial plexus block, intercostal block and the continuous epidural analgesia using both local anesthetics and spinal opioids. The brachial plexus block in continuous form is absolutely able to prevent pain after operations in the shoulder-arm-region and can be prolonged even for weeks using catheter techniques. The intercostal block on the other hand practically can be performed only as single injection technique being relatively simple however from the technical point of view. The catheter epidural analgesia is the most important method within this group. In comparison to the centrally acting opioids the epidural technique brings some distinct advantages especially in the cardiorespiratory risk case. Choosing between "top up"-technique and continuous infusion of the local anaesthetic depends on the individual circumstances the latter method apparently giving a more steady level of analgesia. The spinal opioid techniques finally gain more and more importance during the last years. They present clear advantages over the local anesthetic methods as there are the long lasting analgesia and the selective blockade of pain not touching motor and sympathetic nerve fibers. A delayed respiratory depression however might be a serious danger showing an incidence of 0,3% in the epidural and some 10% in the subarachnoid route. Aiming to inform the clinician once again about the vast field of possibilities available to make the postoperative course painfree it is hoped that this important task in the postoperative period will be handled with more consequence and effectivity in the future.
Bergmann
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H
Bereich Linz, Ludwig Boltzmann-Institut für experimentelle Anaesthesiologie und intensivmedizinische Forschung Wien Linz, Krankenhausstraße 9, A-4020, Linz.