ertent changes in position were immediately corrected. Post-operative course was uneventful without complications.

II.. Case 2
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A 43-year-old man was operated for posterior fossa huge hemangioblastoma in sitting position ([Fig. 3a](#F3){ref-type="fig"}). Various body positions were displayed numerically ([Fig. 3b](#F3){ref-type="fig"}) or in schematic images ([Fig. 3d](#F3){ref-type="fig"}). Monitoring of the table was performed throughout the operation and displayed as a line chart (a part of the line chart is shown in [Fig. 3c](#F3){ref-type="fig"}). The head position in relation to the heart was constantly observed and head position would be changed accordingly to prevent air embolism. The head height ranged from 117 cm to 158 cm, and the height-difference between head and heart position ranged from 27 cm to 31 cm during the operation. No complications happened and the patient made a full recovery from the operation.

III.. Case 3
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A 17-year-old boy with rapid regrowth of pineal immature teratoma was treated by two-staged right and left paramedian transtentorial and supracerebellar approaches in sitting position. At the first stage, the height difference between head and heart was 31 cm, and small amount of air emboli was detected during craniotomy procedure ([Fig. 4](#F4){ref-type="fig"}, the position is depicted in green color). Using this position as a reference, we performed the second stage operation successfully in a better position and without any complications (the difference between head and heart position was reduced to 25 cm). No air emboli were detected during the second operation.

Discussion
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As physiologic parameters such as blood pressure, heart rate, central venous pressure, and oxygen saturation are monitored continuously during surgery, we believe that monitoring of body positions is also essential. Patient position is important for surgeons, anesthesiologists, nurses, and other members of the operating team. Monitoring patient position is currently used 