Metoprolol, fentanyl and stress response to microlaryngoscopy. Effects on arterial pressure, heart rate and plasma concentrations of catecholamines, ACTH and cortisol
Forty patients undergoing microlaryngoscopy were anaesthetized with thiopentone and nitrous oxide. Twenty patients received metoprolol 200 mg in a slow-release tablet once daily for 4 days up to, and including, the morning of operation, and lOmgi.v. shortly before induction of anaesthesia. The other patients received placebo tablets and physiological saline i. v., instead-Both groups of 20 patients were further subdivided, half of the patients receiving fentanyl 1.0-1.5mg during anaesthesia, the effect of which was antagonized by naloxone at the end of the procedure. The other patients received saline i.v. instead of fentanyl or naloxone. Metopropolol decreased heart rate and the general level of arterial pressure during anaesthesia, but did not affect the fluctuations in pressure. Arterial plasma noradrenaline concentrations during microjaryngoscopy were >nlmnr<-H by metoprolol, in comparison with placebo, the reverse being the case for cortisol concentrations. Fentanyl decreased arterial pressure and plasma ACTH and cortisol concentrations regardless of whether the patient had received metoprolol. Plasma adrenaline and noradrenaline concentrations were decreased by fentanyl in the patients receiving metoprolol
