Which administration route of fentanyl better enhances the spread of spinal anaesthesia: intravenous, intrathecal or both?
To enhance the spread of spinal anaesthesia, fentanyl may be administered intrathecally (i.t.) or intravenously (i.v.). The purpose of this prospective study was to investigate the effects of fentanyl administered i.v., i.t. or concurrently by both i.v. and spinal routes on the spread of spinal anaesthesia. Methods:
Sixty patients were randomly assigned to one of three groups. In Groups I and II, spinal anaesthesia was performed with plain bupivacaine 10 mg plus 20 µg fentanyl and in Group III with 10 mg of plain bupivacaine. The level of first peak sensory block was marked. In addition, fentanyl 50 µg was administered i.v. in Groups II and III or by saline in Group I after the sensory blockade reached the highest dermatomal level. Ten minutes after i.v. administration, the level of the second peak sensory block was marked. The distance between the first- and second-highest levels of sensory block was measured. Results:
The distance between the first- and second-highest level of sensory block was significantly different for the three groups: Group II (5.8 ± 2.6 cm) > Group III (2.9 ± 2.1 cm) > Group I (−0.15 ± 1.7 cm). The peak dermatomal level of spinal block was significantly higher in Group II [T4 (T3–T7)] than in Group I [T6 (T4–T9)] and Group III [T6 (T4-T8)]. In Groups I and II the sensory block regressed to S2 for a longer period of time than it did in Group III. Conclusion:
Both the spinal and systemic administration of fentanyl enhanced the spread of spinal anaesthesia. The co-administration of spinal and i.v. fentanyl produced a greater increase in the cephalad spread of spinal block.