Does adding intravenous fentanyl to caudal block in children enhance the efficacy of multimodal analgesia as reflected in the plasma level of catecholamines?

Background and objective: Several studies showed that single analgesic modality management can attenuate perioperative stress, but little is known about the effect of multimodal analgesia on catecholamine responses to surgical trauma in children. Methods: Fifty children (American Society of Anesthesiologists Grade I or II) were randomly allocated to one of two groups: one received general anaesthesia and a caudal block (control group), and one group was given general anaesthesia, caudal block and intravenous (i.v.) fentanyl 2 μg kg^-1 (fentanyl group). Plasma epinephrine and norepinephrine concentrations were measured three times during the perioperative period: at induction time (T₀), at the end of surgery (T ₁) and when the children were fully awake in the postanaesthesia care unit (T₂). Results: There was a significant reduction in the catecholamine levels in the two groups when (T₁) and (T₂) were compared with T₀. When plasma epinephrine levels (at T ₀, T₁ and T₂) between the two groups were compared, a statistically significant reduction at T₂ was obtained in the fentanyl group, when compared with the control group. However, plasma norepinephrine levels showed no statistically significant difference between the two groups (at T₀, T₁ and T₂). Conclusion: These findings suggest that the multimodal analgesic approach of adding i.v. low-dose fentanyl to a caudal block may decrease the plasma epinephrine release in children undergoing inguinal herniotomy.