Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of enflurane, halothane, and isoflurane for diagnostic and therapeutic procedures in children with malignancies.
The authors performed a randomized, prospective trial comparing enflurane, halothane, and isoflurane (each administered with nitrous oxide) to establish which inhaled anesthetic produced the fewest complications and the most rapid induction of anesthesia for children undergoing general anesthesia for diagnostic procedures as oncology outpatients. Sixty-six children, ranging from 8 months to 18 years, underwent a total of 124 anesthetics. Induction of anesthesia (time from placement of facemask to beginning of skin preparation) was faster with halothane (2.7 +/- 1.0 min, mean +/- SD, n = 46) than with enflurane (3.2 +/- 0.8 min, n = 43) or isoflurane (3.3 +/- 1.2 min, n = 35). ⋯ During the maintenance of, emergence from, and recovery from anesthesia, coughing occurred most frequently with isoflurane. During the recovery period, headache occurred most frequently with halothane (9%); there were no significant differences in the incidence of nausea, vomiting, hunger, or depressed effect. The authors conclude that the rapid induction and minimal airway-related complications associated with halothane anesthesia make it an excellent anesthetic agent for pediatric patients undergoing short diagnostic procedures.
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The comparative effects of low doses (0.03-0.04 mg/kg) of epidural morphine on a nociceptive flexion reflex of the lower limb and on postoperative pain in volunteer patients were studied after orthopedic surgery on one knee. According to the stimulation parameters, it was found that 40-50 min after the injection, morphine produced an increase of 87% and 83% of the reflex threshold and of the threshold of maximal reflex response, respectively, as well as a 80-90% depression of the nociceptive responses when elicited by a constant level of stimulation. Onset of pain relief occurred by the 25th min and increased to a maximum stable level 40-50 min after the injection. These data support the hypothesis that the main site of the pain-relieving effect of epidural morphine is located directly at a spinal level.
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Comparative Study
Inspiratory work with and without continuous positive airway pressure in patients with acute respiratory failure.
To compare the effects of continuous positive airway pressure (CPAP) with those of ambient end-expiratory pressure (T-tube) on lung mechanics and blood gas exchange, transpulmonary pressure (Ptp), tidal volume (VT), respiratory frequency, and arterial oxygen and carbon dioxide tensions were measured in 16 spontaneously breathing patients recovering from acute respiratory failure. These variables were measured during breathing through a T-tube; with 18, 12, and 6 cmH2O CPAP; and again during breathing through a T-tube. During all levels of CPAP, mean effective lung compliance (Ceff) was higher and mean total pulmonary power during inspiration lower than during breathing through a T-tube before CPAP (P less than 0.05). ⋯ The authors conclude that CPAP, when adjusted to the appropriate levels, improves lung mechanics in patients recovering from acute respiratory failure. Continuous positive airway pressure reduces total pulmonary power during inspiration and at the same time improves oxygen and carbon dioxide exchange. In these respects, it is preferable to breathing through a T-tube without CPAP.
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The effects on fertility and reproductive wastage of 110 female Swiss/Webster mice and postnatal survival of their offspring were examined after exposure to either air, 0.4% isoflurane, or 0.1% isoflurane. Treatments were for 4 h daily for 2 weeks before and during pregnancy. ⋯ The lack of toxicity of isoflurane is consistent with the results of other reproductive studies in animals that have examined chronic intermittent exposure to subanesthetic concentrations of halothane, enflurane, methoxyflurane, and nitrous oxide. They suggest that these and lower (trace) levels of anesthetic gases may not be the cause of the harmful reproductive effects said to occur in operating room personnel.