[Standards of various national societies and their actual use in practice].
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Austria↗
Biomedical subjects
A M Beaufort
Publications and source records attributed to A M Beaufort.
The influence of hypothermia (surface cooling) on the time-course of action and on the pharmacokinetics of rocuronium in humans.
Hypothermia prolongs the time-course of action of non-depolarizing neuromuscular blocking agents. The mechanism, however, is unknown. We studied the influence of hypothermia (by surface cooling, nasopharyngeal temperature < or = 31 degrees C) on the time-course of action and on the pharmacokinetics of rocuronium in humans. Nineteen neurosurgical patients were divided into hypothermic and normothermic groups. Hypothermia (30.4 +/- 0.8 degrees C (mean +/- SD)) increased the duration of action, temperature dependently, and delayed the recovery. Hypothermia reduced the plasma clearance significantly (2.17 +/- 0.62 vs. 4.26 +/- 0.50 mL kg-1 min-1, P = 0.004), did not change the volume of distribution (224 +/- 64 vs. 232 +/- 60 mL kg-1 min-1, P = 1.0), and prolonged the mean residence time (108 +/- 39 vs. 56 +/- 19 mL kg-1 min-1, P = 0.01). We conclude that hypothermia prolongs the duration of action of rocuronium and delays spontaneous recovery and that altered pharmacokinetics, such as a decreased clearance, play an important role in this.
Androstanols↗
Preliminary investigations of the clinical pharmacology of three short-acting non-depolarizing neuromuscular blocking agents, Org 9453, Org 9489 and Org 9487.
Three muscle relaxants, Org 9453, Org 9489 and Org 9487, short-acting in animals, were investigated to establish their profiles in humans. Potency, time course of action, and pharmacokinetic behaviour were studied in 90 healthy patients during fentanyl/halothane/N2O anaesthesia. Neuromuscular function was monitored mechanomyographically. Plasma and urine concentrations (three patients per compound) were measured by HPLC, and these data were analyzed by iterative linear least square regression analysis. The ED90 values for Org 9453, Org 9489 and Org 9487 were 1.4, 0.45 and 1.15 mg.kg-1 respectively. The onset times of Org 9453 (1.5 mg.kg-1, 1.1 X ED90), Org 9489 (0.9 mg.kg-1, 2 X ED90) and Org 9487 (1.5 mg.kg-1, 1.3 X ED90) were 1.2, 1.6 and 1.5 min, and the durations until 25% twitch recovery were 8.6, 22.0 and 8.9 min, respectively. Clearances of these doses were 6.9, 5.8, and 11.1 ml.kg-1.min-1, and mean residence times 26, 79, and 41 min, respectively. Mean renal excretion (parent compound and metabolites) within 24 hr amounted to 5, 11.3 and 12.2% respectively. No side effects other than a moderate short-lasting decrease of blood pressure and a concomittant increase in heart rate were noted. It is concluded that Org 9453 and Org 9487 are short-acting muscle relaxants in humans.
Adolescent↗
The isolated heart-lung preparation in the cat. An in situ model to study the role of the lungs in the disposition of drugs.
In the search for drugs with an extreme short time course of action, compounds should be developed that are rapidly distributed to and temporarily stored in well-perfused organs. Since the lungs receive the complete cardiac output and have the ability to temporarily store drugs, we have developed an in situ, isolated lung preparation in the cat to study the contribution of the lungs to the disposition of drugs. The cat's own heart perfuses the lung in situ with autologous blood. The circulation between the left ventricle and the right atrium is short-circuited via an aorta-caval shunt. The right forelimb is added to study pharmacodynamics simultaneously (only for muscle relaxants). Validation of the model for 180 min of perfusion showed complete isolation of the organs without major biochemical changes or edema and a stable muscle response. In pilot experiments with two structurally related muscle relaxants, initial muscle relaxation was followed by spontaneous recovery of neuromuscular function and a gradually decreasing plasma concentration, indicating partial disposition by the lungs. This was confirmed by direct concentration measurements in the lung. The present model may provide a powerful experimental tool to elucidate the role of the lungs in the disposition of drugs.
Albumins↗
Innervator NS 252, a new, constant current and programmable peripheral nerve stimulator.
A peripheral nerve stimulator should be able to deliver a constant current to provide supramaximal nerve stimulation even under conditions of increasing resistance. We tested a new programmable peripheral nerve stimulator, the Innervator NS 252. It was able to maintain a constant current of 80 mA up to a resistance of 3.9 kohm. The pulse appearance was correct and there were only small variations in stimulation time intervals. The different type of double burst stimulation and the lack of synchronization with the previously applied stimulus pattern may be regarded as slight disadvantages.
Electric Impedance↗