[Analgesia-sedation for maxillo-facial surgery with midazolam-pentazocine and miazolam-ketamine. Clinical double-blind study of anxiety, analgesia, sedation and amnesia].

UNLABELLED

Ketamine and midazolam, applied as intravenous medication for conscious sedation in day-case maxillo-facial surgery, has been proven to be superior to pentazocine and midazolam concerning cardiovascular parameters and respiratory depression. The aim of this study was to evaluate the effects of low-dose ketamine/midazolam on anxiety, analgesia, amnesia and subjective feelings. METHODS. 140 out-patients (ASA I) were randomly divided into four groups. The double-blind study was prospective.

CONTROL GROUP

Local anaesthesia (LA), articaine 4% plus epinephrine 1:200,000 (n = 35); test group P/M: LA, additional pentazocine 0.40 mg/kg bw and midazolam 0.075 mg/kg bw i.v. (n = 35); test group K25/M: LA, additionally ketamine 0.25 mg/kg bw and midazolam 0.075 mg/kg bw i.v. (n = 35), test group K50/M: LA, additionally ketamine 0.5 mg/kg bw and midazolam 0.075 mg/kg bw i.v. (n = 35). LA was injected 3 min after application of the systemic medication in the test groups or application of a placebo (saline 0.9%) in the control group. Three further minutes later, operation was started. For evaluation questionnaires, visual analogue scales (VAS) and the state-trait anxiety inventory (STAI) were used. For testing retrograde and anterograde amnesia, acoustic sensations were delivered before application of the systemic medication (a Christmas carol) and during operation (the German national anthem). RESULTS. The control group and the test groups were comparable with regard to biological data, duration of operation, applied dosage of local anaesthetics and actual anxiety before operation. The patients in all test groups rated intraoperative anxiety as mild, in contrast to the control group. Nearly no pain sensation during the operation was remembered in all test groups. Retrograde amnesia was not found in any group. Complete anterograde amnesia was observed in all test groups with respect to the intraoperative sensation, but even in the control group 50% of the patients did not remember having heard the national anthem. As subjective feelings negative criteria were mainly reported in the control group, where as in all test groups positive sensations dominated. Dreams were reported mostly after the higher dosage of ketamine, but no patient experienced any unpleasant dreams. The clinical assessment of the different regimes were excellent for test groups P/M and K50/M, modest for the control group and test group K25/M. Postoperatively, patients of test group P/M were remarkably sedated, but no clinically relevant sedation or motor weakness were observed in the other groups. Postoperative pain sensations were rated more intense in all test groups than in the control group. In test groups P/M and K25/M an increasing pain level was recorded during the postoperative period, with the consequence of a higher demand rate for analgesics. CONCLUSIONS. Dental surgery can be performed safely with low-dose ketamine/midazolam. Compared to pentazocine/midazolam, the higher dosage of ketamine (0.5 mg/kg bw) showed identical results intraoperatively, but was superior during the postoperative period (vigilance), and thus may represent a suitable dosage. The lower dosage of ketamine resulted in worse operating conditions, but a dosage higher than 0.5 mg/kg bw might lead to unconscious sedation and might increase the frequency of unpleasant dreams.