Preemptive analgesia--treating postoperative pain by preventing the establishment of central sensitization.
Severe dull pain on the side of tourniquet application and marked rises in blood pressure and heart rate associated with that pain are often observed even under adequate regional analgesia. The purpose of this study was to evaluate the effect of epidural fentanyl on the suppression of tourniquet pain during orthopedic surgical procedures. Forty-five patients undergoing orthopedic surgery of the lower extremities with a tourniquet were maintained by continuous epidural anesthesia with 2% lidocaine through an epidural indwelling polyethylene catheter (L3–4). The patients were randomly allocated to the following three groups: epidural fentanyl (100μg) (epidural group,n=15); intravenous fentanyl (100μg) (intravenous group,n=15); control (no fentanyl) (control group,n=15). The epidural or intravenous fentanyl was administered at the time of the second lidocaine injection. The severity of tourniquet pain based on the patient's level of complaint and the total dose of supplemental analgesics requested in the epidural group were significantly lower than those in the control group. Blood pressure during tourniquet application in the epidural group was more stable than in the other two groups. No severe side-effects were observed in any patient. Prophylactic epidural administration of fentanyl might be useful in the suppression of tourniquet pain.