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[Patient-controlled administration of alfentanil during interventional measures--an alternative to general anesthesia].

OBJECTIVE
In 360 patients undergoing extracorporal shock wave lithotripsy (ESWL) the effects of an opioid analgesia with alfentanil (Rapifen) were investigated.


METHODS
Starting with an intravenous bolus injection of 30 micrograms/kg repetitive injections of 15 micrograms/kg were administered when pain recurred. In 12 patients arterial blood samples were taken to determine alfentanil serum concentrations and blood gases. The pharmacokinetics of alfentanil were described by an open two-compartment model.


RESULTS
In spite of multiple applications of the opioid no relevant cumulation could be seen. Although the patients received 3 l/min of oxygen via nasal tube, a significant decrease in paO2 was observed. pH was decreased and there was a significantly increased paCO2. No significant changes in arterial blood pressure were observed. Two patients developed rigidity of the chest wall.


CONCLUSION
For short operations with only mild noxious stimuli opioid analgesia with alfentanil is a suitable procedure if applied by an experienced anaesthesiologist.