Der Anaesthesist
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Randomized Controlled Trial Comparative Study Clinical Trial
[Studies using S-(+)-ketamine on probands. Computerized EEG-analysis and transcranial Doppler ultrasonography].
It has been shown in the recent literature that the anaesthetic potency of the ketamine isomer S(+)-ketamine is twice that of the racemic mixture used in clinical practice. METHODS. With approval of the local ethics committee, we investigated the effects of a bolus injection of 2 mg/kg racemic ketamine or 1 mg/kg S(+)-ketamine, respectively, on the electroencephalogram (EEG) and transcranial Doppler sonography (TCD) of the middle cerebral artery in ten healthy volunteers by means of a randomised, double-blind, cross-over design. ⋯ However, the relative lower proportion of slow EEG activity at the end of the study might indicate a better recovery of cortical function following S(+)-ketamine than after racemic ketamine. Assuming a close relationship between cerebral blood flow velocity and cerebral blood flow, our TCD results suggest that both racemic ketamine and S(+)-ketamine will considerably increase cerebral blood flow in spontaneously breathing volunteers. Such an effect has been observed by others and, at least partly, can be explained by a concomitant increase in arterial carbon dioxide partial pressure.
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Randomized Controlled Trial Clinical Trial
[Cerebral effects of ketanserin. The influence on hemodynamics and brain metabolism].
Ketanserin, a 5HT2- and alpha 1-receptor antagonist, decreases blood pressure by decreasing systemic vascular resistance without causing reflex cardiac stimulation, while cardiac output remains unchanged. To date, little is known about the effects of ketanserin on cerebral haemodynamics and cerebral metabolism. According to a recently published study, ketanserin seems not to impair cerebral blood flow autoregulation in man. ⋯ As CO2-responsiveness with ketanserin was higher in group 1 but lower in group 2 than without ketanserin, the direction in which ventilation was changed rather than ketanserin was responsible for these changes in CO2-responsiveness. Neither during normocapnia nor during hypocapnia did ketanserin have any effects on cerebral metabolic activity. Thus, it can be concluded that ketanserin does not impair CBF regulation and metabolism and that cerebral vascular responsiveness to hypocapnia is preserved.
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Randomized Controlled Trial Comparative Study Clinical Trial
[Ketamine racemate or S-(+)-ketamine and midazolam. The effect on vigilance, efficacy and subjective findings].
Ketamine is a racemic mixture containing equal amounts of optical isomers that have almost identical pharmacokinetic properties but different pharmacodynamic effects. The S-(+)-isomer of ketamine has about twice the anaesthetic and analgesic potency of the racemic ketamine preparation and is judged to induce less psychic emergence reactions and to be followed by a more rapid recovery of vigilance. The present study was designed to assess whether the S-(+)-isomer of ketamine is superior to the racemic mixture in cardiovascular characteristics, emergence reactions and cognitive functions, and whether side effects may be reduced or prevented by administration of midazolam prior to injection of S-(+)-ketamine. ⋯ The clinical use of S-(+)-ketamine therefore seems to be justified. Premedication with benzodiazepines, e.g. midazolam, is essential. The dose to be administered, however, should be carefully selected in order not to abolish the positive effect of S-(+)-ketamine on vigilance by the sedative effects of the benzodiazepine.
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PEEP has become a widely used ventilatory technique. The beneficial effects of PEEP were first described in asphyctic neonates, and it was later used in the treatment of cardiogenic pulmonary edema. Since the 1970s PEEP has been well established for the treatment of ARDS; the technique is also used for scoring the degree of severity of ARDS. ⋯ PEEP should be used in cardiogenic pulmonary edema as well as in ARDS; there are few contraindications. To choose the individual level of PEEP, PEEP should be titrated in 3- to 5-cm increments and its effects on haemodynamic function, pulmonary gas exchange and respiratory mechanics taken into account. In this article the effects of PEEP, its use and abuse are reviewed from a practical point of view.
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Being advanced in years is not in itself a high risk in anaesthesia; however, altered pharmacokinetics and pharmacodynamics, mental dysfunction and the administration of anaesthetics complicate the postoperative period. In order to examine the problem of sedation in elderly patients, we studied the effects and side effects of continuous peridural anaesthesia for abdominal surgery. METHODS. ⋯ CONCLUSIONS. If carried out by an experienced physician, continuous peridural anaesthesia can be an alternative method in abdominal surgery for elderly patients. We see advantages in the minimal disturbance of pulmonary and mental function, in the minimal amount of sedation required and in the successful postoperative pain therapy.