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.

[Histological study on gland tissue in the median region of the lingual root--morphology of the foramen cecum and posterior lingual gland]

The lingual root is an area where the thyroid gland develops and small salivary glands composed of both serous and mucous glands are distributed in the submucosa. In this paper the foramen cecum and mucous glands at the root of the tongue were histologically investigated in serial sagittal sections of the medial portion of the lingual root. The materials were obtained from 59 autopsied cases, excluding the cases with metabolic disease, brain tumor and neck tumor in whom the original disease might exert direct or indirect effects to the gland tissue. The frontal end was determined to be the line which connects the right and left palatoglossal arch junctions with the tongue, and the rear end the line of transition of the vallecula to the epiglottis. The specimen was cut in half along the median lingual sulcus and median glossoepiglottic fold. Each serial section of 4 microns in thickness was cut from the median plain to the lateral and stained with Hematoxylin-Eosin or Pas-Alcian blue at pH 2.5. The results of the study were summarized as follows. 1) The foramen cecum was histopathologically confirmed in 12 cases out of 59 (20%). The ratio of the detection did not show any difference between both sexes and in the groups of different age. 2) The mucous gland opening into the mucosal epithelium, which were located at the side of the lingual apex from the Ebner's gland or serous gland, were detected in 45 out of 59 (76%).(ABSTRACT TRUNCATED AT 250 WORDS)