[The behavior of the stress hormones cortisol, somatotropin (STH) and prolactin during anesthesia induction with midazolam-alfentanil in comparison with thiopental].

In the present study, not only circulatory parameters but also serum concentrations of the stress hormones cortisol, Somatotropin and prolactin after endotracheal intubation were determined during narcosis. In 19 patients undergoing neurosurgical vertebra disc operations, general anaesthesia was induced with midazolam and alfentanil, while a control group of 8 patients was given thiopentone. The stress hormones were determined by radioimmunoassay immediately prior to and 1, 3 and 6 minutes after intubation. The induction of anaesthesia with the combination midazolam-alfentanil resulted in considerably fewer alterations of hemodynamic parameters such as arterial blood pressure and heart rate than the induction with thiopentone in both groups could be observed. A direct effect of thiopentone and midazolam on prolactin release could be excluded in a comparative study in which comparable amounts of these substances were administered without intubation. After alfentanil a slight, insignificant rise in the prolactin level occurred. Evaluation of such a short stimulus as endotracheal intubation by so-called stress hormones has not yet been satisfactorily achieved.