Der Anaesthesist
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Randomized Controlled Trial Clinical Trial
[The interaction of nitrous oxide and enflurane on the EEG median of 2-3 Hz is additive, but weaker than at 1.0 MAC].
The aim of this study was to quantify the interaction of enflurane and nitrous oxide at a constant median EEG frequency. ⋯ The interaction of enflurane and nitrous oxide in the dose range from 0 to 75 vol.-% on median EEG frequency is compatible with additivity. The potency of nitrous oxide as a substitute for enflurane is less than might be expected when adding up the MAC values.
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Randomized Controlled Trial Clinical Trial
[Perioperative physiological and cognitive functions following oral premedication with 3.75 mg midazolam in operations with retrobulbar anesthesia].
The number of surgical procedures performed as day surgery has significantly increased in recent years. Therefore, a safe and short postoperative recovery period has become increasingly important. The aim of the present study was to investigate perioperative cognitive and physiological function after oral premedication with low-dose midazolam (3.75 mg), especially during the postoperative period. ⋯ Oral administration of low-dose midazolam (0.049 +/- mg/kg) seems to be appropriate for premedication before ambulatory surgical procedures in elderly patients. In the interest of patient safety, standardised oral premedication with 3.75 mg midazolam may not be sufficient for some of the patients.
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Randomized Controlled Trial Clinical Trial
[The effect of a heat and moisture exchanger (HME) on bronchial mucus transport in a closed inhalation anesthesia system].
The administration of dry anaesthetic gases for ventilation leads to morphological changes of the tracheobronchial epithelium that may cause postoperative pulmonary complications. Therefore, additional humidification with a heat and moisture exchanger (HME) is suggested for ventilation during anaesthesia, particularly when using semi-open breathing systems. Recommendations concerning the use of a HME in the semi-closed system are controversial. There are no data in the literature as to whether a HME improves mucociliary transport under these conditions. We therefore studied bronchial mucus transport velocity (BTV) with and without the use of a HME in the semi-closed circle system in humans. ⋯ BTV does not improve with the use of a HME in the semi-closed circle system with a fresh gas flow of 31. With modern anaesthesia machines lower fresh gas flows should be administered, whereby the humidity and temperature of the inspired gases are further increased.
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Heated humidifiers (HH) as well as heat and moisture exchangers (HME) are commonly used in intubated patients as air-conditioning devices to raise the moisture content of the air, thus preventing mucosal damage and heat loss resulting from ventilation with dry inspired gases. In contrary to HME, HH are able to add heat and moisture to the inspired air in surplus, which is often stressed as an advantage in warming hypothermic patients or reducing major heat losses, e.g., during long operations. The impact of air conditioning on the energy balance of man was calculated comparing HME and HH. ⋯ The water content in the inspired and expired air is the most important parameter for estimating pulmonary heat loss in mechanically ventilated patients. In adults (minute volume approximately 71/min) the main fraction of pulmonary heat loss results from water evaporation from the airways (approximately 6 kcal/h), whereas the heat loss due to convection is negligible (approximately 1.2 kcal/h). In intubated patients ventilated with dry air, the heat loss increases to approximately 8 kcal/h due to greater water evaporation from the airways. Both HME and HH are able to reduce the pulmonary heat loss to 1-2 kcal/h. In normothermic as well as hypothermic patients, HH do not offer significant advantages in heat balance compared to effective HME. In conclusion, air conditioning in intubated patients is neither a powerful too for maintaining body temperature during long-lasting anaesthesia nor a sufficient method of warming hypothermic patients in intensive care units.