Articles: pain.
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Acta Anaesthesiol Belg · Jan 1988
Balanced anesthesia and patient-controlled postoperative analgesia with fentanyl: minimum effective concentrations, accumulation and acute tolerance.
Minimum effective fentanyl concentrations (MEC) were determined in 230 ASA I-III patients undergoing a variety of elective surgical procedures under balanced anesthesia, and in 40 patients recovering from comparable operations and anesthesia during postoperative intravenous self-administration of fentanyl (demand dose 34.5 micrograms) by means of the On-Demand Analgesia Computer. Following induction of anesthesia with fentanyl 4 micrograms/kg, repetitive fentanyl reinjections (0.1-0.2 mg) were given intraoperatively whenever systolic blood pressure or pulse rate increased to more than 20% of preinduction values, resulting in an intraoperative fentanyl consumption of 4.2 +/- 1.2 micrograms/kg/h. Duration of postoperative patient-controlled analgesia (PCA) was 20.2 +/- 4.3 h during which time 15.5 +/- 12.9 demands per patient were registered, resulting in a postoperative fentanyl consumption of 0.46 +/- 0.35 micrograms/kg/h. ⋯ Individual MECs increased gradually during anesthesia (mean slope 0.0191 ng/ml/min) but decreased under PCA conditions (-0.0008 ng/ml/min); difference not significant. While the postoperative decrease could be explained by diminishing pain intensity during the observation period, the slight intraoperative increase is discussed as acute tolerance rather than as accumulation. It is concluded that repetitive fentanyl injections as indicated by clinical needs will not lead to relevant accumulation in serum, and that analgesic therapy should be individualized both intra- and postoperatively.
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Clin Exp Hypertens A · Jan 1988
Relationship between pain sensitivity, cardiovascular reactivity to cold pressor test and indexes of activity of the adrenergic and opioid system.
An association between increased blood pressure levels and hypoalgesia has been reported in the experimental animal and in man. The relation between pain perception and cardiovascular function is however still obscure. ⋯ No significant difference was observed between the two groups for casual blood pressure, heart rate and PRA. Compared to subjects with low tolerance to pain, those with high tolerance to pain were significantly older and had: 1) significantly higher levels of diastolic blood pressure and of beta endorphin levels during cold pressor test; 2) significantly higher beta-endorphin levels after cold pressor test; 3) a significantly higher excretion of noradrenaline (but not of adrenaline and dopamine).
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The discovery of opiate receptors and then their endogenous ligands in 1974 (Snyder et al., 1974) has elucidated a vast pharmacology of opiates providing a basis for their diverse clinical applications. With the awareness of quality of life as a primary goal in terminal cancer patients, widespread attention has been drawn to the direct delivery of long-term intraspinal analgesics to cancer patients for who all medical pain control regimens have failed (Coombs & Saunders, 1974). Intraspinal administration of opiates and nonopiate analgesics is not only appealing on theoretical grounds but provides a minimally invasive method to insure otherwise unobtainable pain relief while eliminating obtundation and systemic side-effects associated with conventional therapy (Cobb et al., 1984; Harbaugh et al., 1982; Leavens et al., 1982; Malone et al., 1985; Onofrie et al., 1981; Poletti et al., 1981). Although intraspinal opiates have been used in the treatment of postoperative and benign-pain syndromes (Asari et al., 1981; Cousins & Mather, 1984), in our discussion we review the basic science, current techniques and possible future improvements in spinal analgesia in the control of chronic cancer pain.
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Comparative Study
Receptor organization of opioid and adrenergic regulation of pain.