Anesthesiology
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A case report of soda-lime dust contamination of the breathing circuit of an anesthesia machine causing bronchospasm in a patient is presented. Various factors in absorber design and increased dusting of soda lime due to high-flow techniques and lack of wetting are described. A modification of the Fraser-Sweatman absorber leading the fresh gas into an area free of dust accumulation has resulted in near-complete elimination of the problem.
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Comparative Study Clinical Trial Controlled Clinical Trial
Relative analgesic potencies of morphine and hydromorphone in postoperative pain.
Because of discrepancies in the estimates of the relative analgesic potencies of hydromorphone and morphine, the drugs were compared in two four-point, double-blind bioassays. In the first study, hydromorphone, 1 and 2 mg, was compared with morphine, 5 and 10 mg, in 31 postoperative patients; in the second, hydromorphone, 0.5 and 1 mg, was compared with morphine, 5 and 10 mg, in 112 postoperative patients. Subjective responses to nurse-observer questions were used to quantitate analgesia for postoperative pain. Hydromorphone is more potent than commonly believed: approximately 0.9 to 1.2 mg is equianalgesic with 10 mg of morphine, with a similar incidence of side effects.
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Two important measures may be derived from patient responses to a range of anesthetic doses. The AD50, corresponding to MAC, estimates the median anesthetic concentration--that dose where half the patients are anesthetized and half are not. The AD95 approaches the theoretical "minimum" anesthetic concentration by estimating the dose that anesthetizes 95 per cent of a patient population. ⋯ Recomputed from available data , the AD50's of nine inhaled anesthetics proved to be numerically identical to their MAC values. The AD95's of nine inhaled anesthetics proved to be numerically identical to their MAC values. The AD95's were 5 to 40 per cent greater than the AD50's.)Key workd: Potency, anesthetic, MAC, AD50, AD95; Pharmacology, dose-response curves.)