Previous study showed that different volume of injections (1.0 ml/kg vs. 1.5 ml/kg) during caudal anesthesia showed siginifiant increase of optic nerve sheath diameter in group of high volumes. Increase of ICP can result in harmful effect including reduced cerebral flow and oxygen saturation. Also, increase of ICP can cause headache, syncope and transient loss of visual acuity. The proven and valid method of measuring ICP indirectly is using optic nerve sheath diameter. This study was designed to examine the changes of optic nerve sheath diameter and cerebral oxygenation when equal volume of contrast medium or normal saline was injected in epidural space.
One method of indirect measurement of intracranial pressure is using optic nerve sheath diameter. There is no study whether equal volume of contrast medium injection has any increasing effect of optic nerve sheath diameter.~This study is designed to measure the changes of optic nerve sheath diameter and cerebral oxygenation when equal volume of contrast medium or normal saline was injected in epidural space.