RESUMO
AIM OF INVESTIGATION: We examined whether a pre-emptive analgesic effect could be achieved with ropivacaine, which has less cardiovascular and central nervous system toxicity than bupivacaine, in adults undergoing tonsillectomy. METHODS: The study was carried out in 80 patients in a randomised, double-blind fashion. The patients were randomly assigned to one of four groups. In group I, 3 ml ropivacaine 7.5 mg/ml were injected pre-operatively 5 minutes before the start of OR into each tonsil bed. In group II, 3 ml ropivacaine 7.5 mg/ml were injected post-operatively into each tonsil bed. In group III, 3 ml NaCl were injected pre-operatively 5 minutes before the start of OR into each tonsil bed. In group IV, 3 ml NaCl were injected post-operatively into each tonsil bed. The analgesic effectiveness was measured post-operatively by the use of a visual analogue scale, a numeric rating scale (at rest and during activity) and by measuring the total analgesic consumption (mefenamic acid) in the first 192 hours. In addition the time of first analgesic request was noted. Vital parameters and side-effects were documented. RESULTS: There was no significant difference between the groups in the time of first analgesic request. Likewise, there was no significant difference in the post-operative cumulative analgesic consumption between the four groups. The post-operative administration of ropivacaine resulted in significantly lower pain scores at certain time points compared with the other groups as measured both with the visual analogue scale and the numeric rating scale (at rest). It must be emphasized, that the pain scores both at rest and with exertion remain high and that the net analgesic consumption (per day) remains constant for the first 8 post-operative days. CONCLUSIONS: We could demonstrate no significant pre-emptive analgesic effect with ropivacaine in adults undergoing tonsillectomy in our study. One can, however, recommend the administration of ropivacaine post-operatively after tonsillectomy, since a reduction of pain scores can thereby be achieved. For post-operative analgesia we recommend the combination of a non-opioid analgesic with a weak opioid.
