Anesthesiology
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The radioactive microsphere technique was used to determine the distribution of cardiac output and regional blood flow in rhesus monkeys before and 10,20,40, and 80 minutes after induction of spinal anesthesia. Five monkeys were studied during low spinal anesthesia (sensory level T10) and five other monkeys were studied during high spinal anesthesia (sensory level T1). Each monkey served as its own control. ⋯ Blood flows to heart, brain, and lower extremity during T1 spinal anesthesia showed only non-significant changes. Vascular resistance in the lower extremity was significantly reduced during both levels of spinal anesthesia, indicating arteriolar dilatation. Also, during both levels of anesthesia, the lungs received an increased proportion of the radioactive microspheres, suggesting increased peripheral arteriovenous shunting of microspheres due to the arteriolar dilatation.
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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.