Epidural analgesia in veterinary critical care

Effect of body position on cranial migration of epidurally injected methylene blue in recumbent dogs

“…It has been shown that epidural cranial migration may be affected by gravity because the caudally located thoracic and cranially located lumbar vertebrae, especially T13, are higher than other vertebrae when an animal is in sternal recumbency. 2,7 Gravity may have an effect not only on epidural cranial migration but also on concentration of the local anesthetic at the site of interest, as indicated by faster onset and greater duration of action. 14 The gravity effect may be used to influence the distribution of analgesia by placing the patient on the affected side for 15 to 20 minutes after the epidural injection.…”

“…14 The gravity effect may be used to influence the distribution of analgesia by placing the patient on the affected side for 15 to 20 minutes after the epidural injection. 1,2,7 However, surgical procedures frequently require the affected leg to be on the nondependent side, forcing the patient to be turned after some time has passed and potentially affecting the migration of the epidural injectate.…”

Myoclonus and hyperalgesia following intended epidural morphine administration in a dog

“…Epidurals are usually performed at the lumbosacral space in dogs as this provides the largest area for access to the epidural space (Valverde 2008). Lumbosacral intrathecal injections can be performed but it is recommended to reduce the dose of drug given to a quarter to a half of that normally given epidurally (Wetmore and Glowaski 2000). It is possible in this case the injection may have been intrathecal rather than epidural, and the caudal position of the spinal cord meant that accidental penetration into the subarachnoid space would have been possible.…”

Distribution of new methylene blue injected into the lumbosacral epidural space in cats

“…There is a potential effect of gravity on solution distribution because the caudal thoracic and cranial lumbar vertebrae, especially the 13th thoracic vertebra, are higher than other portions when animals are in sternal recumbency. This effect may be used to influence the distribution of analgesia by placing the patient on the affected side for 15–20 minutes after injection (Pascoe 1997; Wetmore & Glowaski 2000; Jones 2001). However, in sternal recumbency, height difference between the caudal thoracic and lumbosacral space may represent an obstacle to cranial migration of solution, i.e.…”