Turkish Journal of Medical Sciences

Abstract: Aim: The aim of this study was to determine the effects of low and moderate doses of dexmedetomidine infusions by evaluating hemodynamic and neuroendocrine responses in patients undergoing elective transurethral surgery. Materials and Methods: Fifty patients were randomly allocated to receive 0.45 (Group 1) or 0.6 (Group 2) µg kg^-1 hr^-1 dexmedetomidine infusion 10 minutes before induction of anesthesia. Heart rate, blood pressures, ETCO2 and peripheral oxygen saturation values and parameters of non-invasive cardiac output were monitored. Measurement times were baseline (I), after dexmedetomidine infusion (II), after thiopental induction (III), after intubation (IV) and at 10-minute intervals during desflurane anesthesia. Anesthesia (2L min^-1 50% N₂O+O₂) was maintained with 4-6% desflurane corresponding to a bispectral index (BIS) value of 40-60. Venous blood samples were collected prior to intubation (I), at the 30^th min intraoperatively (II) and after extubation (III) to determine plasma adrenaline and noradrenaline levels. Chi-square, Student's t-test and repeated measures of variance were used for statistical analysis. Results: Two different doses of dexmedetomidine infusion produced similar hemodynamic effects. The cardiovascular and neuroendocrine parameters were suppressed more in Group 2 than in Group 1. Conclusions: These findings suggest that intraoperative 0.45 and 0.6 µg kg^-1 hr^-1 doses of dexmedetomidine result in similar intubation, recovery and hemodynamic responses. Cardiovascular and neuroendocrine parameters were suppressed more by the moderate dose of dexmedetomidine.

Key Words: Alpha-2 agonist, dexmedetomidine, autonomic nervous system, catecholamine, neuroendocrine response