the small dose of ketamine prevents the hemodynamic disturbance in patients who underwent phacoemulsification with topical anesthesia and monitored anesthesia care

background: ketamine is the only anesthetic agent that leads to an increase of blood pressure and heart rate by activation of sympathetic nervous system. however, there is a controversy about this effect of ketamine especially if used in small dosage. we proposed to evaluate the hemodynamic effect of small dose of ketamine during phacoemulsification. methods: one hundred patients of asa physical status i-iii were chosen for this prospective, randomized, double-blind placebo-control study. our patients were assigned randomly to two groups, ketamine group (n=50) and a control group (n=50).  after premedication, 0.15 mg/kg ketamine was injected intravenously in ketamine group. after three minutes phacoemulsification was begun under topical anesthesia. the hemodynamic variables were recorded during the procedure and compared between two groups. results: the systolic, diastolic and mean blood pressure were statistically significantly higher in the ketamine group (p<0.001) during the procedure. the heart rate during operation was higher in the ketamine group compared to control group (p<0.001). 46 (92%) patients in the ketamine group and 38 (76%) patients in the control group were satisfied according to surgeons (p=0. 001). nausea and vomiting occurred at similar rates in each group. also, hallucination and other psychological events did not occur in either of the groups. conclusion : we found that systolic, diastolic, mean arterial blood pressure in patients who received small dose of ketamine were higher during the operation.