It is reported that optic nerve sheath diameter increases when higher volume of medication is injected during epidural anesthesia.

This study is designed to compare the optic nerve sheath diameter using 10cc of nomal saline of different speed (3cc/sec vs. 1cc/sec).

It is known that insufficient intraoperative or postoperative management can lengthen the hospital stay with unwanted complications. Therefore, active and proper management using continuous thoracic epidural catheterization is suggested good option to prevent such potential complication.

According to previous study, injection of different volume of local anesthetics (1.0 ml/kg vs. 1.5 ml/kg) during caudal anesthesia, high volume of local anesthetics resulted in significant increase of intracranial pressure (ICP). Increase of ICP can reduce regional cerebral flow and oxygen saturation causing the safety of patients. In addition, increase of ICP can result in headache, syncope, and transient loss of visual acuity.

Although it is very invasive method, ICP can be measured directly at the brain parenchyme. Among methods to measure the ICP indirectly, measurement of optic nerve sheath diameter using ultrasound is known to reflect the degree of ICP. It is reported that optic nerve sheath diameter increases when higher volume of medication is injected during epidural anesthesia.

This study is designed to compare the optic nerve sheath diameter using 10cc of nomal saline of different speed (3cc/sec vs. 1cc/sec).

Inclusion Criteria:

• lung cancer
• liver cancer
• stomach cancer
• pancreas cancer

Exclusion Criteria:

• coagulopathy
• infection
• previous spine fusion at thoracic level
• previous brain surgery