[The use of remifentanil in critically ill patients. Clinical findings and early experience].

OBJECTIVES: It was the aim of this investigation to report our initial clinical experience on the use of remifentanil in critically ill patients undergoing mechanical ventilation. Additionally, we hypothesized that even under intensive care conditions remifentanil might facilitate a temporally predictable and "programmed" tracheal extubation.
METHODS: Remifentanil was used for analgesia and sedation of mechanically ventilated patients who were admitted to the ICU following major noncardiac surgery or who had to be ventilated due to respiratory failure. The infusion was started with 0.15 microg/kg/min and then adapted in steps of 0.05 microg/kg/min according to clinical needs. After admission to the ICU the depth of sedation was adjusted to a Ramsay score level of 4 (sleeping patient, immediately arousable) and then targeted at a level of 2-3 (patient awake, co-operative and tranquil or responding to command only). In case of sufficient pain relief but inadequate sedation patients could receive bolus doses of midazolam (1-3 mg) or an infusion of clonidine (0.5 microg/kg/h), the latter especially in case of shivering or hypertension. Prior to extubation bolus doses of piritramide (3-5 mg) and a non-opioid analgesic (metamizol or propacetamol) could be used for postoperative pain relief. Data are presented as mean+/-SD.
RESULTS: A total of 46 patients were studied, aged 62.8+/-15.4 yr with a mean APACHE II score of 19.2 points. The duration of remifentanil infusion ranged up to 78 h with a mean of 9. 8 h. The mean infusion rate was 0.14+/-0.08 microg/kg/min during ongoing analgesia and sedation and 0.10+/-0.08 microg/kg/min immediately before its discontinuance. Additional sedatives were necessary in 63% of all patients. Emergence was rapid in the majority of cases: 67% of all patients could safely be extubated within 15 min after termination of remifentanil, and a total of 87% were extubated within 45 min. A development of tolerance was not observed during the study period.
CONCLUSIONS: Remifentanil appeared to be suitable for analgesia and sedation of critically ill patients undergoing mechanical ventilation: Even under intensive care conditions recovery was rapid in the majority of cases, and in two thirds of all patients tracheal extubation was temporally predictable and could be timed within 15 min. These results are best explained by the metabolism and offset of action of remifentanil obviously unaffected in the ICU area. However, for fast emergence the cautious use of additional sedatives is crucial.