Anesthesia and analgesia
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Anesthesia and analgesia · Aug 1996
Comparative StudyIn vivo imaging of human limbic responses to nitrous oxide inhalation.
Human behavioral studies have shown that nitrous oxide, in subanesthetic concentrations, impairs psychomotor function, cognitive performance, and learning and memory processes. However, the cerebral mechanisms of such effects remain unknown. Positron emission tomography (PET) was used to map the brain areas associated with nitrous oxide effects. ⋯ Nitrous oxide inhalation was associated with significant activation in the anterior cingulate cortex, a limbic area known to mediate psychomotor and cognitive processes. Deactivation was found in the posterior cingulate, hippocampus, parahippocampal gyrus, and visual association cortices in both hemispheres; the former two regions are known to mediate learning and memory. These areas identified by PET in vivo may provide the neuroanatomical basis for the behavioral responses associated with subanesthetic nitrous oxide inhalation.
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Anesthesia and analgesia · Aug 1996
Clinical Trial Controlled Clinical TrialAlfentanil dose-response relationships for relief of postoperative pain.
The aim of this study was to characterize within-patient alfentanil dose-response curves for the relief of spontaneous postoperative pain and to test the closeness of relationships 1) between pain intensity and alfentanil analgesic requirements, and 2) between alfentanil requirements for analgesic and nonanalgesic (sedative and miotic) effects. The effects of alfentanil were studied in 23 patients after elective abdominal surgery. During a 40- to 60-min testing session, the patient received two intravenous (i.v.) injections of saline (placebo) and up to six 3-micrograms/kg increments of alfentanil at 5-min intervals. ⋯ A strong correlation was found between interpatient variabilities in the analgesic and sedative effects of alfentanil (r = 0.75, P < 0.002). At the same time, the relationship between alfentanil requirements for pain relief and that for pupil constriction did not demonstrate any significant correlation. The results suggest that, in a population of patients with postoperative pain, the intensity of spontaneous pain cannot be the primary factor determining the dose of alfentanil necessary for its relief.
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Anesthesia and analgesia · Aug 1996
Multicenter StudyPercutaneous injuries in anesthesia personnel.
Anesthesia personnel are at risk for occupationally acquired blood-borne infections from human immunodeficiency virus, hepatitis viruses, and others after percutaneous exposures to infected blood or body fluids. The risk is greater after an infected, blood-contaminated, percutaneous injury, especially from a hollow-bore blood-filled needle, than from other types of exposures. Few data are available on the specific occupational hazards to anesthesia personnel from needles and other sharp devices. ⋯ Most CPI occurred between steps of a multistep procedure (8%), were recapping related (13%), or occurred at other times after use (41%). No CPI were reported from use of needlestick-prevention safety devices. The devices and mechanisms of injury identified in this study provide specific data that may lead to prevention strategies to reduce the risk of PI.
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Anesthesia and analgesia · Aug 1996
Carbon dioxide elimination measures resolution of experimental pulmonary embolus in dogs.
Patients with severe pulmonary embolism can suffer progressive hypercapnia refractory to supramaximal mechanical ventilation, and may require open-thoracic or transvenous emergency embolectomy in addition to anticoagulation and/or thrombolysis. The functional recovery of gas exchange would be signaled by an increase in pulmonary CO2 elimination and decrease in CO2 retention; such data could guide the course of operative embolectomy. Accordingly, we studied five chloralose-urethane anesthetized, mechanically ventilated dogs with open thoraces in which the right pulmonary arteries (RPAs) were reversibly occluded with cloth snares. ⋯ QT did not significantly change. We conclude that intraoperative measurement of VCO2,br should immediately detect and follow the resolution of CO2 retention in the lung and peripheral tissues after RPA reperfusion. PETCO2 could not detect the decrease of VCO2,br back to baseline because PETCO2 does not measure exhaled volume or the PCO2 waveform.
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Anesthesia and analgesia · Aug 1996
Comparative StudyHydroxyethyl starch solution attenuates blood-brain barrier disruption caused by intracarotid injection of hyperosmolar mannitol in rats.
This study was performed to investigate whether a fraction of hydroxyethyl starch macromolecules, prepared from pentastarch and known as "Hes-Pz," with molecular weights of 100,000-1,000,000, protects against blood-brain barrier (BBB) disruption due to intracarotid injection of hyperosmolar mannitol. Rats were anesthetized with isoflurane, and retrograde catheterization of a unilateral eternal carotid artery was performed. Except for the Control group (n = 8), hemodilution was performed using lactated Ringer's solution LR group, n = 7), 6% hetastarch (HES group, n = 7), or 6% HES-Pz (HES-Pz group, n = 8) to reduce the hematocrit to about 23%. ⋯ Ki was similar in the CC in all four groups. The Ki in the IC was significantly lower in the HES-Pz(6.4 +/- 3.5 microL.g-1.min-1) than in the Control, HES, or LR group (16.3 +/- 6.1, 19.0 +/- 12.9, 17.9 +/- 10.8 microL.g-1.min-1, respectively). Our data suggest that HES-Pz significantly attenuates disruption of the BBB caused by an injection of hyperosmolar mannitol.