Does Dextrose Affect Analgesia or the Side Effects of Intrathecal Sufentanil?

Effects of intrathecal and i.v. small-dose sufentanil on the median effective dose of intrathecal bupivacaine for Caesarean section

BACKGROUND

Spinal anaesthesia with bupivacaine combined with sufentanil has been widely used for Caesarean section. However, the main site of action (spinal vs central) of intrathecal (IT) sufentanil is controversial. The aim of this study was to examine the predominant mechanism of action of IT, small-dose sufentanil when added to bupivacaine for Caesarean section, by comparing the effects of IT and i.v. sufentanil 2.5 microg on the median effective dose (ED50) of bupivacaine.

METHODS

Ninety parturients undergoing elective Caesarean section with a combined spinal-epidural technique were enrolled into this prospective, double-blind, up-down sequential allocation study. According to the up-down sequential allocation, parturients received varying doses of bupivacaine alone (C group) or co-administered with i.v. sufentanil 2.5 microg group (IVS group; n = 30) or IT sufentanil 2.5 microg group (ITS group; n = 30). The possible maternal or neonatal adverse effects were also recorded.

RESULTS

The ED(50) of bupivacaine was 6.3 mg (95% CI 6.2-6.5) in the C group, 5.2 mg (95% CI 5.1-5.4) in the IVS group, and 3.0 mg (95% CI 2.9-3.1) in the ITS group. The ED50 in the ITS group was significantly lower as compared with the other two groups (P < 0.0005). With the exception of pruritus that exclusively occurred in the ITS group (P = 0.011, compared with the other two groups), no significant differences among groups were observed regarding the frequencies of the maternal or neonatal adverse effects.

CONCLUSIONS

Compared with an equal dose of sufentanil i.v., intrathecally administered sufentanil 2.5 microg has a significant local anaesthetic-sparing effect via a predominantly spinal mechanism for Caesarean section.

Intrathecal plainvs hyperbaric bupivacaine for labour analgesia: efficacy and side effects

PURPOSE

Baricity is an important determinant of block characteristics of the spinal component of a combined spinal epidural (CSE) for labour analgesia. This study compares the analgesic efficacy and side effects of intrathecally administered plain and hyperbaric bupivacaine (both with fentanyl) during active labour.

METHODS

Sixty-two women in active labour (cervical dilatation >or=5 cm and pain score > 5) were randomized in a prospective, single-blinded fashion to receive 2.5 mg of either hyperbaric or plain bupivacaine both combined with 15 microg of fentanyl as the spinal component of a CSE. The primary outcome was failure of satisfactory analgesia within ten minutes of the intrathecal injection as defined by a verbal pain score > 3. Secondary outcomes included need for rescue analgesia, hypotension, respiratory depression, nausea and vomiting, pruritus and sustained fetal bradycardia.

RESULTS

Sixty patients were analyzed. The failure rates were 20% in the hyperbaric group vs 0% in the plain group (P=0.024). The plain solution provided faster onset, higher sensory levels and less motor block at all times during the first 30 min. The incidence of both pruritus and sustained fetal bradycardia was 33% in the plain group and 10% in the hyperbaric group (P=0.03).

CONCLUSION

A plain rather than hyperbaric solution of bupivacaine 2.5 mg with fentanyl 15 microg provides a faster onset of analgesia, higher sensory levels and less motor block, while demonstrating an increased incidence of pruritus and sustained fetal bradycardia.

Hyperbaric bupivacaine 2.5 mg prolongs analgesia compared with plain bupivacaine when added to intrathecal fentanyl 25 microg in advanced labor

We investigated the effect of sequential administration of intrathecal (IT) hyperbaric bupivacaine (after the initial administration of IT hypobaric fentanyl) on the duration of spinal analgesia. Thirty-seven nulliparous parturients with a cervical dilation >/= 5 cm were randomized to receive either IT fentanyl 25 micro g and plain bupivacaine 2.5 mg (group P; n = 19) or IT fentanyl 25 micro g and hyperbaric (with 8% glucose) bupivacaine 2.5 mg (group H; n = 18). The two components of the IT injectate were administered sequentially (fentanyl 25 micro g diluted in 2 mL of normal saline, immediately followed by 0.5 mL of 0.5% bupivacaine). Patients were then positioned with their torso elevated at 30 degrees for 30 min. Pain scores using 0-100 visual analog scales were collected before combined spinal/epidural analgesia and at 5, 15, and 30 min after the block. Patients in Group H had a longer median duration of analgesia (122 min; range, 80-210 min) than Group P (95 min; range, 75-125 min) (P < 0.01). Group H also had a more limited dermatomal spread (median highest sensory level of T8 versus T4 in group P; P < 0.05). The side-effect profile was similar. Under these circumstances, hyperbaric bupivacaine conferred an increased duration of IT analgesia compared with plain bupivacaine.

Fetal bradycardia due to intrathecal opioids for labour analgesia: a systematic review

OBJECTIVE

To evaluate fetal and maternal adverse effects of intrathecal opioid analgesia during labour.

DATA SOURCES

A systematic search was performed, in Medline, Embase, the Cochrane Library, bibliographies, and personal contact with authors, in any language, up to February 2001.

STUDY

selection Full reports on randomised comparisons of any analgesia with intrathecal opioid (experimental group) with any non-intrathecal opioid regimen (control group) during labour.

DATA EXTRACTION

Dichotomous data from 24 trials (3513 women).

RESULTS

With intrathecal opioids, there was a significant increase in the risk of fetal bradycardia: odds ratio 1.8 (95% confidence interval 1.0 to 3.1), number-needed-to-harm 28. The risk of caesarean section due to fetal heart rate abnormalities was similar (6.0% versus 7.8%). The incidence of pruritus was significantly higher with intrathecal opioids: relative risk 29.6 (95% CI 13.6 to 64.6), number-needed-to-harm 1.7.

CONCLUSIONS

Intrathecal opioids for labour increase the risk of fetal bradycardia and maternal pruritus. The risk of subsequent caesarean section is not increased.

Addition of bupivacaine 1.25 mg to fentanyl confers no advantage over fentanyl alone for intrathecal analgesia in early labour

PURPOSE

a) To evaluate the effect of adding 1.25 mg of bupivacaine to intrathecal fentanyl on the duration of analgesia in an Asian population and b) to examine if the baricity of the local anesthetic at this dose has any bearing on the duration and quality of block.

METHODS

Forty-eight parturients in early labour received combined spinal epidural (CSE) analgesia to evaluate a) the effect of adding 1.25 mg of bupivacaine to intrathecal (IT) fentanyl 25 microg on the duration of analgesia and b) the effect of baricity of intrathecal local anesthetic on the duration and quality of the block. Patients were randomly allocated to receive: IT fentanyl 25 microg plus normal saline (Group f, n=16), IT fentanyl 25 microg plus plain bupivacaine 1.25 mg (Group f+pb, n=16) and IT fentanyl 25 microg plus heavy bupivacaine 1.25 mg (Group f+hb, n=16). The two components of the IT injectate (total of 2.25 mL) were given sequentially.

RESULTS

Group f+hb had the lowest sensory dermatomal block (T7 vs T4 (Group f), T5 (Group f+pb), P <0.01). There were no differences in the duration of analgesia and incidence of side effects among the groups.

CONCLUSION

We found no advantage of adding 1.25 mg bupivacaine to fentanyl 25 microg. At this dose, the baricity of bupivacaine has no effect on the duration of analgesia.

Addition of dextrose 3.5% to intrathecal sufentanil for labour analgesia reduces pruritus

PURPOSE

To determine whether the addition of a low concentration (3.5%) of dextrose would minimize pruritus while maintaining the quality of analgesia.

METHODS

In a double blind study 48 parturients in early labour were randomized to one of two study groups: dextrose (Dex, n = 24; 10 microg sufentanil in dextrose 3.5%), or normal saline (NS, n = 24; 10 microg sufentanil in normal saline). Parturients received the study drug as the intrathecal injection of the combined spinal-epidural (CSE) technique for labour analgesia. Duration and degree of analgesia were measured until epidural analgesia was initiated or delivery of the baby. The intensity and distribution (above T6, T6-L1, and below L1) of pruritus were measured at five minute intervals during first 25 min after injection.

RESULTS

Quality and duration of analgesia did not differ between groups, but the overall incidence of pruritus was less in the Dex group (88% vs 42%, P = 0.001). Within each region, the incidence of pruritus was less in the Dex group. In patients who had pruritus, for the Dex group, the incidence of pruritus in the upper region (>T6) was lower than the NS group. There was no difference in the lower regions.

CONCLUSION

The addition of dextrose 3.5% to intrathecal sufentanil reduced the incidence of pruritus without affecting the duration or quality of analgesia in parturients in early labour. The distribution of pruritus in the Dex group was limited to below T6 suggesting that pruritus to intrathecal sufentanil is mediated at the spinal level.