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Patient controlled analgesia (PCA)
Author(s) -
Gordh T.
Publication year - 1993
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1993.tb03658.x
Subject(s) - anesthesiology , medicine , university hospital , pain medicine , citation , intensive care , intensive care unit , library science , family medicine , anesthesia , intensive care medicine , computer science
Twenty years ago, Marks and Sachar pointed out that 32 % of postoperative patients experienced severe distress, despite the analgesic regimen. Another 41 % were in moderate distress. Chart review showed significant undertreatment with narcotics (1). Since this study it has been more or less universally accepted that postoperative patients are inadequately treated for their pain. Later reviews of the literature confirm this picture, suggesting that the situation has improved very little even today (2). The traditional pain therapy after surgery consists of an intramuscular dose of an opioid, which is supposed to last for 3-4hours. The opioids are actually very effective against postoperative pain, so why is their effect not as good as we expect? This is explained by a logistics problem the drug is not in the right place at the right time due to administrative delays (maybe on the shelf and not in the patient) and problems with pharmacokineticsand pharmacodynamicsas well. Intramuscular injection of a standard dose of an opioid gives a delayed effect due to the relatively slow absorption, and the the given dose may have been too low. Intermittent injections give unstable plasma concentrations, and thereby only intermittent pain relief. To obtain any analgesia at all following a certain nociceptive input, the plasma concentration of opioids must exceed a minimal effective analgesic concentration (MEAC) (3). The MEAC-level may vary four-fold between individuals, and is not correlated to sex,height or weight. The explanation of the variation in MEAC seems to be pharmacodynamic rather than pharmacokinetic. The ideal situation is to maintain the opioid concentration above the individual MEAC and below the level causing side effects. Conventional intramuscular injections cannot fulfill this goal. On the other hand, we must not forget that about 50% of the postoperative patients are satisfied with its effects, and this routinemethod will probably remain as the cornerstone of postop analgesia even in the future. If combined with quality assurance in the shape of a regular assessment of pain it will probably work even better (4). Nevertheless, many patients will require something more advanced to get good analgesia in the postop period.