Article
The intraperitoneal pressure as a counterforce to CSF diversion in ventriculoperitoneal shunting: Absolute values and correlations with body measurements in mobile subjects.
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Published: | June 2, 2015 |
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Objective: In ventricluoperitoneal shunting, the intraperitoneal pressure (IPP) counteracts the drainage of the cerebrospinal fluid (CSF) into the peritoneal cavity. Animal studies suggest an intrinsic IPP exceeding the intraperitoneal hydrostatic pressure. No data are available on the intrinsic IPP in mobile humans, which has to be corrected for the hydrostatic pressure.
Method: We measured the IPP indirectly (intravesical pressure) in two body positions (supine/upright). Measurements were referenced against the highest point of the peritoneal cavity, which was estimated by ultrasound of the subcutaneous tissue in the supine position, and accepted to match the height of the xiphoid in the upright position. To evaluate the hydrostatic character of the IPP, measurements were repeated with an altered reference height (-10 cm). Pressure data were given in cmH2O, and analyzed using Student's t-test and Pearson's correlation coefficient.
Results: We included 20 subjects (12 male; 8 female) with a mean age of 60 years, a mean body mass index (BMI; kg/m2) of 32.6 (± 7.7) and a mean abdominal girth of 112 (± 17.7) cm. The IPP was measured in the supine position as mean 3.6 (± 2.4) cmH2O, and 3.4 (± 5.5) cmH2O in the upright position (p=0.9). The mean difference to IPP values obtained in a vertical distance of -10cm was 9.1 (± 1.5) cmH2O. A positive correlation was found between the BMI and the IPP (R=0.8; p<0.001).
Conclusions: Our results support the existence of an intrinsic IPP exceeding the intraperitoneal hydrostatic pressure. The IPP increases according to the hydrostatic force. The correlation of the IPP with the BMI might help to select appropriate shunt valve settings in the future.