European journal of anaesthesiology
-
Review
Systemic and specific autonomic reactions in pain: efferent, afferent and endocrine components.
The sympathetic nervous system is hierarchically organized. At the bottom of this organization are the sympathetic pre-post-ganglionic channels which supply the autonomic target organs, at the top the hypothalamus and cortical structures. Each level of this hierarchy contains neuronal programmes which govern the sympathetic activity in a patterned fashion. ⋯ No conclusive experimental evidence exists to show that peripheral nociceptors are controlled by activity in sympathetic post-ganglionic neurones. In certain pathophysiological situations, however, it may happen that activity in sympathetic post-ganglionic neurones, which supply an extremity, leads to excitation of afferent axons, thus establishing a vicious circle between primary afferent neurones, spinal cord and sympathetic outflow. This situation may occur after partial lesions of peripheral nerves in a syndrome which is called 'reflex sympathetic dystrophy'.
-
In the in vivo rat sciatic nerve tibialis muscle preparation the potency and pharmacodynamics of vecuronium, atracurium, pancuronium, tubocurarine and their combinations were studied. Considering the potency only, there was no beneficial difference between the pure compounds and their combinations. As both vecuronium and atracurium are almost free from side-effects individually, a combination of the two relaxants brings no advantage.
-
Etomidate was administered to six healthy volunteers by microprocessor controlled infusions, to generate three cycles of linearly increasing plasma levels, with an anticipated slope of 0.05 microgram ml-1 min-1. The infusions were stopped when a deep hypnotic state was obtained, as indicated by burst suppressions in the EEG. The infusions were restarted when the volunteers were fully orientated to person, place and time. ⋯ Pharmacokinetic analysis gave a volume for the central compartment of 50 +/- 11 litre, an apparent volume of distribution of 252 +/- 51 litre and a total clearance of 1693 +/- 504 ml min-1. Microprocessor controlled infusions can serve as a powerful tool for research in clinical pharmacology. The achievement of linearly increasing plasma levels of etomidate allowed further pharmacokinetic and pharmacodynamic modelling concepts to be realized.
-
General anaesthesia and many types of acute respiratory failure are accompanied by a decrease in functional residual capacity (FRC). This reduction promotes closure of dependent airways and alveolar collapse, thus impeding ventilation of these regions. Perfusion, on the other hand, is forced towards dependent regions by lowered pulmonary vascular pressure and increased alveolar pressure. ⋯ Application of general positive end-expiratory pressure (PEEP) increases FRC and may improve gas exchange but cannot restore V/Q to normal. Differential ventilation, with equal distribution of ventilation between the lungs, and the application of PEEP solely to the dependent lung (selective PEEP) with the patient in the lateral position, improve V/Q matching and gas exchange with less impedance of cardiac output and less danger of barotrauma. This ventilation technique has proved successful in short-term experiments and in a small number of patients treated over several days.
-
Randomized Controlled Trial Clinical Trial Controlled Clinical Trial
Neuromuscular block: atracurium and vecuronium compared and combined.
The neuromuscular blocking action of atracurium and vecuronium acting separately and in combination have been compared using the evoked EMG of the adductor pollicis muscle. Dose response curves have been drawn for the drugs given separately and found to be nonparallel (P less than 0.05). ⋯ The effect on neuromuscular transmission of a combined medication using equipotent doses of atracurium and vecuronium, determined from the dose response plots, was found to be greater than would be expected by addition of their separate actions. The combination of small doses resulted in significant neuromuscular blockade.