Dural sinus pressure: various aspects in human brain surgery in children and adults

Abstract

To prevent air embolism and minimize neurosurgical venous hemorrhage, the dural sinus pressure (confluens sinuum pressure, CSP) was examined under various conditions in 47 cases, 11 of whom were children. Either the extracranial (group A) or catheter type (group B) pressure transducer was used. The latter gave approximately 30% higher values than the former. In any surgical position, children showed a tendency toward higher pressure than did adults. This was particularly the case in the sitting position; adults showed negative pressure [-8.6 +/- 2.3 (SD) mmHg, group A], whereas all eight children less than 9 yr of age (group A, 5 cases; group B, 3 cases) showed positive pressure. The youngest with negative CSP in a sitting position was a 9-yr-old boy. When the upper half of the body was raised, the CSP decreased linearly and became zero at approximately 25 degrees. In anteflexion of the neck, the CSP decreased significantly, and even with inclination of the upper half of the body of only 15-20 degrees or more upward, negative pressure was observed in adults. In children, right and left rotation of the neck showed remarkable increase of the CSP. In both supine and sitting positions, CSP was elevated sufficiently by bilateral jugular compression to prevent air embolism. Positive-pressure respiration did not raise the CSP, contrary to widely accepted knowledge. This study was originally performed in relation to brain surgery, but the results also seemed to be valuable in physiology.

A global multiscale mathematical model for the human circulation with emphasis on the venous system

“…The introduction of gravity during postural changes will introduce transient flow acceleration and vessel collapse above the right atrium due to negative transmural pressure . Under these circumstances, the wave speed for veins in the collapse region will certainly lead to transcritical flows and therefore will make the algorithm used to treat junctions unsuitable.…”

“…However, we expect that in the case of respiratory manoeuvres, such as Valsalva and Müller manoeuvres, or other situations such as postural changes and exercise, respiration along with venous tone regulation and muscle compression will play a crucial role in the determination of venous haemodynamics. The introduction of gravity during postural changes will introduce transient flow acceleration and vessel collapse above the right atrium due to negative transmural pressure [95,96]. Under these circumstances, the wave speed for veins in the collapse region will certainly lead to transcritical flows and therefore will make the algorithm used to treat junctions unsuitable.…”

Effects of head down tilt on episcleral venous pressure in a rabbit model

“…A potential recurring challenge to IOP homeostasis is posture change with the consequent gravity-dependent changes in cephalic arterial and venous pressures (Krieglstein et al, 1978; Iwabuchi et al, 1983; Bill, 1984; Iwabuchi et al, 1986; Carlson et al, 1987; Gisolf et al, 2004). In humans in the upright position, blood flowing from the heart to the eye and back experiences the force of gravity such that the cephalic arterial and venous pressures are 10 - 15 mmHg lower than in the supine position (Bill, 1984), yet the IOP increase in going from upright to supine is only a few mmHg, much smaller than the changes in cephalic vascular pressures (Krieglstein et al, 1978; Bill, 1984; Carlson et al, 1987).…”

Possible venous air embolism during open eye surgery in a child

“…7 The lower incidence of VAE, as detected by Doppler ultrasonography in children (9.3-37%) 4,6 compared to adults (7-50%) may be explained in part by the relatively high dural sinus pressure in children compared to adults. 8 It is recognized that an equivalent air bubble size would theoretically have a more profound impact in children. Although the lethal volume of air is estimated to be 200 to 300 mL in adults, 9 a slower rate of air entrainment (0.05 to 0.30 mL·kg -1 ·min -1 ) 10 may be tolerated due to the time constant for gas dissipation via the large surface area of the alveoli.…”

“…Administration of positive end expiratory pressure (PEEP) has been used without convincing evidence of any beneficial effect and should be used only to improve oxygenation. Bilateral compression of the jugular veins significantly increases the sagittal sinus pressure 8 but cannot be recommended as part of the initial treatment of VAE during eye surgery 1 Elevated venous pressure may promote collection of air bubbles in the superior vena cava and even in the internal jugular veins reducing the risk of massive air embolism. 20 This can be accomplished by fluid administration.…”