[The significance of dural sinus pressure in neurological surgery-- correlation with surgical position]

A study was made of the significance of confluens sinus pressure in various surgical positions and of various factors influencing confluens sinus pressure. The following findings were obtained: Confluens sinus pressure in various positions was follows: Reverse jackknife position (supine position with upper and lower halves of the body elevated ca 20 degrees) 1.3 +/- 0.8 (Mean +/- SD) cmH2O Sea lion position (prone position with upper and lower halves of the body elevated ca 10 degrees with neck hyperextended) 2.7 +/- 0.6 cmH2O Prone position 5.8 +/- 0.9 cmH2O Supine position 5.9 +/- 1.7 cmH2O Right lateral position 6.9 +/- 0.7 cmH2O Left lateral position 9.6 +/- 1.2 cmH2O Since confluens sinus pressure is strongly affected by gravity, the determination point, the height of the right atrium, and the central venous pressure were referred to when measuring the surgical position. When the upper half of the body was raised (at angle ranging from--10 degrees to +90 degrees) confluens sinus pressure became zero in adults when the angle was +25 degrees or thereabouts. When the angle was +90 degrees, a marked negative pressure of -12.7 +/- 3.0 cmH2O, was observed, suggesting the danger of air embolism. In 4 children under 6 years of ago, however, negative pressure was not observed even at an angle of +90 degrees, although some changes due to different angles were noted. This suggests some specificity of dural sinus pressure. Intrathoracic negative pressure at inspiration, the contraction of skeletal muscles, and profuse hemorrhage, and sympathetic nervous strain were surmised as other factors influencing dural sinus pressure.