Analyse der In-vitro-Funktion verschiedener Anti-Siphon-Ventile in Kombination mit verschiedenen Differenzdruckventilen mit und ohne Bewegung

In vitro performance of six combinations of adjustable differential pressure valves and fixed anti siphon devices with and without vertical motion

by Pauline Röhrig
Doctoral thesis
Date of Examination:2025-01-15
Date of issue:2024-12-13
Advisor:Prof. Dr. Veit Rohde
Referee:Prof. Dr. Veit Rohde
Referee:Prof. Dr. Bernhard Reuß
Persistent Address: http://dx.doi.org/10.53846/goediss-10902

 

 

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Abstract

English

Shunt therapy using adjustable differential pressure valves combined with anti-siphon devices (ASDs) is a well-established approach for treating normal pressure hydrocephalus but continues to pose risks of severe complications, such as overdrainage. This study is aimed to analyze the flow characteristics of 3 commercial differential pressure valves paired with 2 different ASDs under static and dynamic conditions. The differential pressure valves proGAV 2.0 [PG], CertasPlus [CP], and HakimMedos [HM] were evaluated in combination with the gravity-regulated ASD (ShuntAssistant [SA]) and the flow-regulated ASD (SiphonGuard [SG]. Flow data was recorded at differential pressures ranging from 4 to 40 cmH₂O in both stationary setups and during vertical oscillations at frequencies of 2, 3, and 4 Hz. Additionally, the impact of inclination angles (90° vs. 60°) on flow rates was assessed. Results demonstrated that combinations with the gravity-regulated ASD allowed no or minimal flow at low differential pressures in static conditions, while a linear increase in flow occurred at higher pressures. Dynamic testing revealed significant flow increases for these combinations, proportional to oscillation frequency. In contrast, combinations with flow-regulated ASDs exhibited lower flow rates overall, and movement did not increase flow. Instead, the characteristic biphasic flow curve observed under static conditions was eliminated during motion. The distinct flow characteristics of the ASDs highlight the critical importance of selecting appropriate valve combinations for clinical applications. The findings provide valuable insights into tailoring shunt systems to individual patient needs and mitigating complications associated with movement. Further studies should build upon these results to optimize shunt systems and reduce the incidence of overdrainage in clinical practice.
Keywords: hydrocephalus