Investigation of cerebrospinal fluid transition of magnesium sulphate administred through epidural catheter in rabbits

SUMMARY:INVESTIGATION OF CEREBROSPINAL FLUID TRANSITION OFMAGNESIUM SULPHATE ADMINISTERED THROUGH EPIDURALCATHETER IN RABBITSDr. Halil Can Canatan, Anesthesiology and Reanimation Department, Medical Facultyof Dokuz Eylul University, İzmir / TurkeyObjective:This study was designed to investigate the ability of MgSO4, administered invarious doses by epidural catheter, to pass cerebrospinal fluid and evaluate motor block effectof MgSO4 in rabbits.Methods:18 rabbits weighing 2000 to 3000 g were chosen for the study. The subjects wereanesthetized using ketamin for placement of caudal epidural catheter by subcutaneous tunneltechnique. The catheter was fixed to the subjects' back. The subjects were randomized to 3groups each consisting of 6 rabbits.Group 150 (n= 6): 150 mg/mL MgSO4 was administered to all subjects in the group by usingepidural catheter and then the catheter was flushed using 0.20 mL of saline. Group 300 (n=6): 300 mg/mL MgSO4 was administered to all subjects by epidural catheter and then thecatheter was flushed with 0.20 mL of saline. Group 450 (n=6): 450 mg/mL MgSO4 wasadministered to all subjects by epidural catheter and then the catheter was flushed with 0.20mL of saline. Rabbits' ear arteries were cannulated for arterial blood samples. 0.1 mLcerecrospinal fluid sample was taken from cisterna magna using insuline injector passingthrough atlantooccipital ligament. The motor block was scored using Drummond Moorescale.After administration of drug through epidural catheter motor block evaluated and CSFand arterial blood samples were taken at 0., 240., 360. and 480. minutes. Mg2+ level wasmeasured with Stat Profile M device. Pharmacokinetic parameters were also calculated andstatistically evaluated.Results: In our study, spinal CSF ionized magnesium levels were increased compared tobasal Mg2+ levels in each group respectively as follows; 25% for 150 mg, 60% for 300 mg,and 127% for 450 mg. Moreover the arterial ionized Mg2+ levels were shown to increase by13% for 150 mg, 87% for 300 mg, 200% for 450 mg compared to basal Mg2+ levels in eachgroup, respectively. 450 mg Mg2+ sulphate administered epidurally generated motor block.Conclusion: This study has established that epidural administration of MgSO4 increases thespinal cerebrospinal fluid ionized Mg2+ concentration, epidural MgSO4 passes throughsystemic blood circulation and epidural administration of 450 mg MgSO4 generates motorblock.Key words: Epidural, magnesium sulphate, cerebrospinal fluid, blood-brain barrier.