An examination of safety on laparoscopic surgery in patients with ventriculoperitoneal shunt by a CO2 reflux experiment.

When a patient with a ventriculoperitoneal shunt (VPS) undergoes laparoscopic surgery, there is the concern about possible problems with the shunt due to increased intra-abdominal pressure. We conducted a simplified reflux experiment on VPS valves to demonstrate safety. Each of five different VPS valves was connected via tubes to a glass vessel of our own making. Carbon-dioxide gas was consecutively insufflated into the vessel at 3-25 mm Hg pressure to determine whether reflux occurred when the valves and tubes were empty (opened test) and when filled with physiologic saline (closed test). Reflux occurred for two of five valves at an insufflation pressure of 5 mm Hg or more in the opened test, while not for any valves until 25 mm Hg in the closed test. In clinical settings, there would be no possibility of reflux under the pneumoperitoneum in VPS systems draining cerebrospinal fluid. Laparoscopic surgery in patients with VPS would be performed safely if characteristics of VPS valves are taken advantage of.