Der Anaesthesist
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Almost all patients treated with opioids suffer from constipation. Numerous laxatives are used to overcome the problem, but none has yet been found to yield favourable results in all patients. Several studies have attempted to reverse opioid-induced constipation by the use of oral naloxone. Experiments carried out in rats showed that morphine-induced constipation is reduced by oral naloxone without impairment of antinociception [4]. However, evaluation of clinical studies reveals that there is uncertainty about the dosage regimen (the daily dose of naloxone ranged from 0.5% to about 60% that of morphine) and a lack of larger numbers of patients studied. ⋯ The medical history of the 3 patients in whom naloxone failed to abolish constipation revealed neurological disturbances. Treatment of these patients included the use of neuroleptics, antiemetics, and other drugs. In this context, it should be noted that oral naloxone can be expected to abolish only opioid-induced constipation. In conclusion, it was found that the treatment of opioid-induced constipation by administration of oral naloxone produced positive results. A controlled study will show, whether the side effects can be minimized by reducing the naloxone dose.
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Closed-system anaesthesia provides the best prerequisites for optimal warming and humidification of anaesthetic gases. The PhysioFlex anaesthesia machine fascilitates quantitative closed-system anaesthesia. Furthermore, its design may improve the climatization of the anaesthetic gases by revolving the system volume at 70 l/min, using a small soda-lime canister to allow optimal usage of the heat and moisture generated by CO2 absorption and by integrating all system components in thermally isolating housing. To determine the capacity of the PhysioFlex to climatize anaesthetic gases, we evaluated the heat and humidity profile at four characteristic places in the anaesthetic circuit under standardised conditions in a model. ⋯ With the PhysioFlex anaesthesia machine employing closed-system conditions, minimal climatization of anaesthetic gases was reached within 10 min. After a period of 120 min, the anaesthetic gases were nearly climatized to the extent recommended for long-term respiratory therapy. To date, no comparable temperature and humidity level has been reported with conventional anaesthesia machines. The time course of the gradient between M1 and M2 may give an opportunity for further optimising the system in reducing heat loss after the soda-lime canister, the active heat and moisture source in the circuit. At about 32 degrees C, the temperature in the soda-lime canister is 10-15 degrees C less than in conventional anaesthesia machines. Thus, the use of thermally instable volatile anaesthetics in the PhysioFlex under closed-system conditions may be less critical than in conventional anaesthesia machines under minimal-flow conditions.