A RAT MODEL OF CHRONIC LUMBAR EPIDURAL CATHETERIZATION

Authors
Citation
T. Nishiyama, A RAT MODEL OF CHRONIC LUMBAR EPIDURAL CATHETERIZATION, Canadian journal of anaesthesia, 45(9), 1998, pp. 907-912
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Anesthesiology
ISSN journal
0832-610X
Volume
45
Issue
9
Year of publication
1998
Pages
907 - 912
Database
ISI
SICI code
0832-610X(1998)45:9<907:ARMOCL>2.0.ZU;2-O
Abstract
Purpose: There are no rodent models of chronic epidural catheterisatio n which can induce clinically relevant analgesic effects of morphine ( potency ratio of intrathecal:epidural = 10 to 30:1). The purpose of th is study was to investigate a new rat model of chronic epidural cathet erisation by comparing the analgesic effect of epidural and intratheca l morphine. Methods: In Sprague-Dawley rats, for epidural catheterisat ion, a skin incision and muscle dissection were made at T-13 level in the midline. The intervertebral ligament was cut to insert an epidural catheter (polyethylene tube; outer diameter 0.14 mm) 2 cm caudally. T he distal end of the catheter (0.61 mm) was passed sc to exit in the d orsal neck area. For intrathecal catheterisation, the atlanto-occipita l membrane was incised to insert a catheter (0.61 mm) 8.5 an caudally. The effects of morphine (1, 3, 10, 30, or 100 mu g.10 mu l(-1) intrat hecally, and 30, 100, or 300 mu g.5, 10, or 20 mu l(-1) epidurally) on thermal escape latency were investigated by a hot box test. Behaviour and motor function were also tested. Results: A volume of 20 mu l ind uced greater analgesic effect than 5 and 10 mu l epidural administrati on. The ED50 of epidural morphine (94.1 mu g) was 30 times more than t hat of intrathecal morphine (3.1 mu g). Conclusion: A new rat model of chronic epidural catheterisation is described, which provides a simil ar analgesic epidural:intrathecal potency ratio for morphine to that i n humans when morphine is administered in a volume of 20 mu l.