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The cardiovascular actions of three concentrations of desflurane (formerly I-653), a new inhalation anesthetic, were examined in 12 unrnedicated normocapnic, normothermic male volunteers. We compared the effects of 0.83, 1.24, and 1.66 MAC desflurane with measurements obtained while the same men were conscious. Desflurane caused a dose-dependent increase in right-heart filling pressure and a decrease in systemic vascular resistance and mean systemic arterial blood pressure. As measured by echocardiography, left ventricular end-diastolic area did not change except for a small increase at 1.66 MAC desflurane, and systolic wall stress was less at all concentrations of desflurane than during the conscious state. Desflurane did not change cardiac index or left ventricular ejection fraction. Heart rate did not change at 0.83 MAC, but progressively increased with deeper desflurane anesthesia. Stroke volume index was less at all concentrations of desflurane than while the men were conscious, but desflurane did not alter the velocity of ventricular circumferential fiber shortening. Mixed venous blood Po, and oxyhemoglobin saturation were higher during all concentrations of desflurane anesthesia than during the conscious state. No volunteer developed a metabolic acidosis. We conclude that desflurane with controlled ventilation and constant Paco, causes cardiovascular depression, as indicated by the increased cardiac filling pressure and decreased stroke volume index and by no change in the velocity of circumferential fiber shortening in the presence of decreased systolic wall stress. However, cardiac output is well maintained, and heart rate does not increase at light levels of anesthesia. The cardiovascular actions of 0.83 and 1.66 MAC desflurane were also reexamined in 6 of the 12 men during the seventh hour of anesthesia. Prolonged desflurane anesthesia resulted in lesser cardiovascular depression than was evidenced during the first 90 min. The measures of cardiac filling (central venous pressure and left ventricular enddiastolic cross-sectional area) did not differ between the early and late periods of anesthesia. Systemic vascular resistance decreased further during the late period, but systolic wall stress did not differ between the two time periods. During the seventh hour of desflurane anesthesia, heart rate and cardiac index were higher at both anesthetic concentrations than during the first 90 min of anesthesia. Left ventricular ejection fraction and velocity of fiber shortening did not change with duration of desflurane anesthesia. Oxygen consumption, oxygen transport, the ratio of the two, mixed venous Po,, and mixed venous oxyhemoglobin saturation (Sod increased late in the anesthetic in comparison with the first 90 min. (Anesth Analg 1991;7314>56) esflurane (formerly 1-653) is a new inhaled anesthetic, structurally similar to isoflurane, D but with advantageous lower blood (1) and tissue (2) solubilities, and little or no metabolism (3-5). The cardiovascular effects of desflurane in ~~ ~ ~~swine do not differ...

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Intravenous infusion of morphine sulfate in rats for 24 hours produced marked opioid dependence, manifested by a series of well-documented signs appearing after injection of the opiate antagonist naloxone. Treatment of rats with naloxonazine significantly reduced the analgesia associated with the morphine infusions for more than 24 hours. Furthermore, 14 of 16 withdrawal signs observed in naloxonazine-treated rats were virtually identical to those in rats that received morphine alone. These results raise the possibility that different receptor mechanisms mediate morphine analgesia and many of the withdrawal signs associated with morphine dependence.

The low solubility of sevoflurane in blood suggests that this agent should enter and leave the body more rapidly than isoflurane. However, the closeness of sevoflurane and isoflurane tissue/blood partition coefficients suggests that the rates of equilibration with and elimination from tissues should be similar. We tested both predictions, comparing sevoflurane with isoflurane and nitrous oxide in seven volunteers. We measured the rate at which the alveolar (end-tidal) (FA) concentration of nitrous oxide increased toward an inspired (FI) concentration of 65%-70%, then measured the concurrent rise in FA and mixed expired concentrations (FM) of sevoflurane and isoflurane at respective FI values of 1.0% sevoflurane and 0.6% isoflurane for 30 min. Minute ventilation (VE) was measured concurrently with the measurements of anesthetic concentrations. For the potent agents, we also measured VE, FA, and FM for 6-7 days of elimination. FA/FI values at 30 min of administration were as follows: nitrous oxide, 0.986 +/- 0.003 (mean +/- SD); sevoflurane, 0.850 +/- 0.018; and isoflurane, 0.733 +/- 0.027. FA/FA0 (FA0 = the last FA during administration) values after 5 min of elimination were as follows: sevoflurane, 0.157 +/- 0.020; isoflurane, 0.223 +/- 0.024. Recovery (volume of anesthetic recovered during elimination/volume taken up) of sevoflurane (101% +/- 7%) equaled recovery of isoflurane (101% +/- 6%). Time constants for a five-compartment mammillary model for sevoflurane were smaller than those for isoflurane for the lungs but were not different from isoflurane for the other compartments.(ABSTRACT TRUNCATED AT 250 WORDS)

We examine racial and ethnic differences in opioid prescribing and dosing for long bone fractures at emergency department (ED) discharge. Methods:We conducted an electronic health records-based cross-sectional study of adults with long bone fractures who presented to the ED across 22 sites from a health care delivery system (2016 to 2017). We examined differences in opioid prescribing at ED discharge and, among patients with a prescription, differences in opioid dosing (measured as morphine milligram equivalents) by race/ethnicity, using regression modeling with statistical adjustment for patient, fracture, and prescriber characteristics.Results: A total of 11,576 patients with long bone fractures were included in the study; 64.4% were non-Hispanic white; 16.4%, 7.3%, 5.8%, and 5.1%, respectively, were Hispanic, Asian, black, and of other or unknown race; and 65.6% received an opioid at discharge. After adjusting for other factors, rates of opioid prescribing were not different by race/ethnicity; however, among patients with an opioid prescription, total morphine milligram equivalent units prescribed were 4.3%, 6.0%, and 8.1% less for Hispanics, blacks, and Asians relative to non-Hispanic whites. Conclusion:Racial and ethnic minority groups with long bone fractures receive similar frequencies of opioid prescriptions at discharge, with a small potency difference. How this affects pain relief and why it happens is unclear. [Ann Emerg Med.