The Negative Effects of Patient Controlled Sedation Using Midazolam for Cataract Surgery under Retrobulbar Block / 대한마취과학회지

ABSTRACT

BACKGROUND: Careful sedation is needed for cataract operation that requires absolute cooperation of elderly patients. Patient-controlled sedation (PCS) allows patients themselves change the dose of sedatives along with their need. The goal of this study was to find out midazolam PCS could achieve an adequate sedation without complications during cataract surgery and the differences of patients who needed PCS or not. METHODS: PCS with midazolam was applied to 33 patients undergoing cataract surgery using retrobulbar block (midazolam, bolus 0.5 mg, lock out interval 3 minutes, 1 hour limit 4.5 mg). PCS pump was given to patients 30 min before retrobular block. And patients themselves decided to use or not to use PCS after full explanation on PCS. Sedation score, visual analogue scale of anxiety, cognitive function, side effects and satisfaction of PCS were measured. RESULTS: PCS users were 22 (67%). Mean midazolam dosage of PCS users was 2.03 mg. Preoperative and intraoperative anxiety score were 40.2 mm and 13.0 mm in PCS users and 15.5 mm and 21.8 mm in non-users. The difference between PCS users and non-users was only preoperative anxiety levels. Age, sex, weight, education levels, previous cataract surgery, preoperative desired sedation levels did not influence on the PCS using. There was positive correlation of midazolam doses with only preoperative anxiety levels. 76% of surgeons and 85% of patients were satisfied with PCS but 7 patients showed involuntary movement. Cognitive functions and discharge time were not influenced by PCS. CONCLUSIONS: Although patients and surgeons were satisfied with the midazolam PCS, 33% of patients did not need PCS and deep sedation with involuntary movement that could bring surgical complications was resulted in some PCS users. We conclude that PCS for cataract surgery would be safer when it is administered under careful supervision of anesthesiologist.