Distribution of Methylene Blue after Injection into the Epidural Space of Anaesthetized Pregnant and Non-Pregnant Sheep

Abstract

The aim of the study was to determine the distribution of different volumes of methylene blue solution injected into the epidural space in anaesthetized pregnant and non-pregnant sheep, to evaluate its cranial distribution and to compare between them. Fifteen pregnant and fifteen non-pregnant sheep were included in the study. Sheep were anaesthetized and received 0.05, 0.1, or 0.2 mL/kg of a lumbosacral epidural solution containing 0.12% methylene blue in 0.9% saline. Thirty minutes after the epidural injection, the ewes were euthanized. The extension of the dye within the epidural space was measured, and the correlation between the volume of the dye injected and the number of stained vertebrae was evaluated. The cranial migration of the dye between pregnant and non-pregnant sheep was also compared. The results show that the volume of methylene blue injected epidurally into pregnant and non-pregnant sheep correlated directly with its cephalic distribution into the epidural space; and a volume of 0.1 mL/kg or 0.2 mL/kg stained up to the first lumbar segment in pregnant and non-pregnant sheep, respectively. Also, the results suggest that the volume of drugs administered into the epidural space of pregnant sheep should be half the volume that would be used in non-pregnant sheep.

Discogenic Back Pain: Literature Review of Definition, Diagnosis, and Treatment

“…Methylene blue has been tried for intradiscal injection, to chemically ablate nerve endings . Methylene blue injection into the epidural space has been tried in animal models, but not introduced for human use because of its potential neurotoxic effects . Current spinal or intradiscal injections and procedures have no demonstrated effects on IVD regeneration, and are not able to completely stop the progression of the degeneration cascade.…”

NIR fluorescent small molecules for intraoperative imaging

“…MB, perhaps the second most widely researched compound in image-guided surgery not because of its NIR fluorescence but its color staining properties 48,49 unfortunately suffers from nondependable optical properties. [50][51][52][53][54][55][56][57] The absorption and fluorescence characteristics are at appropriate wavelengths during in vitro experimentation; however, the redox state of the compound allows for the reduction of the central imine to the corresponding amine which destroys the NIR fluorescence of the compound. These nonoptimum properties along with low extinction coefficient and nonamenability to the addition of a targeting ligand limit the overall utility of this particular contrast agent.…”