Der Anaesthesist
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Randomized Controlled Trial Clinical Trial
[Local oxygen supply to the cerebral cortex during thiopental and propofol anesthesia. First results].
Because the brain is highly vulnerable to damage from even a brief imbalance of oxygen delivery and demand, intraoperative disturbances of local oxygen supply must be avoided. Until now, there has been no method allowing fast and reliable intraoperative measurement of the local oxygen supply in the human brain. Intraoperative investigations were therefore performed using the Erlangen micro-lightguide spectrophotometer. ⋯ In all patients receiving propofol anaesthesia higher local SO2 values were found, even if the patients first received thiopentone (values in parenthesis). The mean local SO2 amounted to 65.4% (57.3%) in the propofol group and 38.8% (45.2%) in the thiopentone group. The number of values below 25% SO2 was 5.6% (5.8%) in the propofol group and 18.7% (19.1%) in the thiopentone group.
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Comparative Study
[The effect of changes in lung compliance on ventilation in newborns. Results of animal experiments with two different respirators].
In most ventilators used in anaesthesia tidal volume delivered during mechanical ventilation is different from the tidal volume preset at the respirator on the basis of respirator and circuit compliance and gas compression during inspiration. The error in ventilation due to the compressed volume is especially significant clinically when the tidal volume is very small or when the airway pressure is very high. In newborns and neonates in particular, decreasing lung compliance during a surgical procedure may contribute to marked hypoventilation. ⋯ This reflected by an increase in peak inspiratory pressure and can be corrected by increasing the respiratory rate. In contrast, the CICERO is able to preserve ventilation by an internal correction for gas compression, but it does not guarantee normoventilation in all cases. In neither group does the end-tidal PCO2 reflect the true ventilation during decreasing lung compliance, so that arterial blood gas analysis seems to be mandatory for the diagnosis of hypercapnia in such situations.