European journal of anaesthesiology
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The influence of several intravenous anaesthetics on the heart was assessed using the isolated rat heart-lung preparation. Each group received 10(-3)mol litre-1 and 10(-4)mol liter-1 of ketamine, 6 micrograms ml-1 and 60 micrograms ml-1 of midazolam, 6 micrograms ml-1 and 60 micrograms ml-1 of diazepam or 0.6 micrograms ml-1 and 6 micrograms ml-1 of flunitrazepam. Systolic blood pressure in rats receiving high doses of midazolam, diazepam and ketamine were higher than that in the control group. ⋯ None of the intravenous anaesthetics, even in doses which were 100 times greater than therapeutic doses, showed any depressant effects in this preparation. Moreover, it is surprising that midazolam and diazepam produced direct increases in myocardial contractility. These results suggest that the cardiodepressant effects of intravenous anaesthetics may be due to their effects on the central nervous system.
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Randomized Controlled Trial Clinical Trial
Thiopentone, thiopentone/ketamine, and ketamine for induction of anaesthesia in caesarean section.
Seventy-five healthy patients were randomly allocated to receive thiopentone, thiopentone/ketamine or ketamine for induction of anaesthesia for elective Caesarean section. Thiopentone resulted in the most pronounced and ketamine in the smallest drop in blood pressure, while the combination induced only moderate haemodynamic changes. ⋯ The muscle tone of neonates in the thiopentone group was more reduced than in neonates in the other two groups. Infants delivered after uterine incision-to-delivery intervals exceeding 3 min more often had Apgar scores < 7 than those delivered in less than 3 min.
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The time profile of the neuromuscular block produced by a single bolus administration of vecuronium was simulated by a new model for the access of the relaxant to the receptors on the motor end plates. The receptors were assumed to be kinetically a part of the interstitial space of the muscle. ⋯ The model describes well the time lag needed to reach the peak submaximal block, its magnitude, as well as the time course of recovery from the maximal block. The limits of the model, evident in less than optimal simulation of the neuromuscular block by two doses of vecuronium in rapid succession, were attributed to the inadequate description of the vecuronium concentrations in plasma immediately after the bolus injection.
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Auditory continuous reaction time was studied in three treatment groups. Twenty opioid naive patients received intramuscular morphine 0.15 mg kg-1 bodyweight for premedication. Thirty-one cancer patients were treated with oral opioids, 180 mg morphine per 24 h (median). ⋯ The reaction time was measured using 152 auditory signals and summarized as 10%, 50% and 90% percentiles. Analysing reaction time distributions, the opioid naive patients showed the greatest difference to the control group in the shortest reaction times while chronic opioid users showed the greatest difference for the longest reaction times. There seems to be a qualitative difference in reaction time distribution, between opioid naive individuals treated with single dose morphine and cancer patients in long-term treatment.
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Biphasic Positive Airway Pressure (BIPAP) can be described as pressure controlled ventilation in a system allowing unrestricted spontaneous breathing at any moment of the ventilatory cycle. It can also be described as a Continuous Positive Airway Pressure (CPAP) system with a time-cycled change of the applied CPAP level. As with a pressure controlled, time-cycled mode, the duration of each phase (T(high), T(low)) as well as the corresponding pressure levels (P(high), P(low)) can be adjusted independently. ⋯ Furthermore, spontaneous breathing of the patient does not necessitate any switching of the mode of ventilation. The transition from controlled to augmented ventilation is smooth. BIPAP enables the therapist to let the patient breathe freely even under the most invasive ventilation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)