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Laboratory study on "intracranial hypotension" created by pumping the chamber of a hydrocephalus shunt.

Bromby A, Czosnyka Z, Allin D, Richards HK, Pickard JD, Czosnyka M - Cerebrospinal Fluid Res (2007)

Bottom Line: All models were able to produce negative pressures ranging from -11.5 mmHg (Orbis-Sigma valve) to -233.1 mmHg (Sinu-Shunt).The number of pumps required reaching these levels ranged from 21 (PS Medical LP Reservoir) to 315 (Codman Hakim-Programmable).The maximum pressure change per pump ranged from 0.39 mmHg (Orbis-Sigma valve) to 23.1 (PS Medical LP Reservoir).

View Article: PubMed Central - HTML - PubMed

Affiliation: Academic Neurosurgical Unit, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK. apb49@cam.ac.uk <apb49@cam.ac.uk>

ABSTRACT

Background: It has been reported that pumping a shunt in situ may precipitate a proximal occlusion, and/or lead to ventricular over-drainage, particularly in the context of small ventricles. In the laboratory we measured the effect of pumping the pre-chamber of hydrocephalus shunts on intracranial hypotension.

Materials and methods: A simple physical model of the CSF space in a hydrocephalic patient was constructed with appropriate compliance, CSF production and circulation. This was used to test eleven different hydrocephalus shunts. The lowest pressure obtained, the number of pumps needed to reach this pressure, and the maximum pressure change with a single pump, were recorded.

Results: All models were able to produce negative pressures ranging from -11.5 mmHg (Orbis-Sigma valve) to -233.1 mmHg (Sinu-Shunt). The number of pumps required reaching these levels ranged from 21 (PS Medical LP Reservoir) to 315 (Codman Hakim-Programmable). The maximum pressure change per pump ranged from 0.39 mmHg (Orbis-Sigma valve) to 23.1 (PS Medical LP Reservoir).

Conclusion: Patients, carers and professionals should be warned that 'pumping' a shunt's pre-chamber may cause a large change in intracranial pressure and predispose the patient to ventricular catheter obstruction or other complications.

No MeSH data available.


Related in: MedlinePlus

Bar chart showing the pressures for the various valves at which the asymptote was achieved by continuously pumping the reservoirs.
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Figure 4: Bar chart showing the pressures for the various valves at which the asymptote was achieved by continuously pumping the reservoirs.

Mentions: The lowest pressures obtained at the asymptotes following continuous pumping of the valve reservoirs revealed a range of differences between the shunts (Fig. 4). All shunts were capable of creating negative pressures. The shunt able to achieve the lowest negative pressure was the Sinu-Shunt (-233.1 mmHg). The shunt that achieved the least negative pressure was the Orbis-Sigma valve (-11.5 mmHg). These values are significantly different (P < 0.05 One-way ANOVA on Ranks). The Codman Non-Programmable Valve produced a significantly lower pressure when using the large pumping chamber (regular Codman-Hakim valve) compared to a smaller pre-chamber (pediatric micro valve) (P < 0.001 One-way ANOVA and Tukey's test). There was no difference in performance between configurations of the Strata valve or between the different flow control models.


Laboratory study on "intracranial hypotension" created by pumping the chamber of a hydrocephalus shunt.

Bromby A, Czosnyka Z, Allin D, Richards HK, Pickard JD, Czosnyka M - Cerebrospinal Fluid Res (2007)

Bar chart showing the pressures for the various valves at which the asymptote was achieved by continuously pumping the reservoirs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1851975&req=5

Figure 4: Bar chart showing the pressures for the various valves at which the asymptote was achieved by continuously pumping the reservoirs.
Mentions: The lowest pressures obtained at the asymptotes following continuous pumping of the valve reservoirs revealed a range of differences between the shunts (Fig. 4). All shunts were capable of creating negative pressures. The shunt able to achieve the lowest negative pressure was the Sinu-Shunt (-233.1 mmHg). The shunt that achieved the least negative pressure was the Orbis-Sigma valve (-11.5 mmHg). These values are significantly different (P < 0.05 One-way ANOVA on Ranks). The Codman Non-Programmable Valve produced a significantly lower pressure when using the large pumping chamber (regular Codman-Hakim valve) compared to a smaller pre-chamber (pediatric micro valve) (P < 0.001 One-way ANOVA and Tukey's test). There was no difference in performance between configurations of the Strata valve or between the different flow control models.

Bottom Line: All models were able to produce negative pressures ranging from -11.5 mmHg (Orbis-Sigma valve) to -233.1 mmHg (Sinu-Shunt).The number of pumps required reaching these levels ranged from 21 (PS Medical LP Reservoir) to 315 (Codman Hakim-Programmable).The maximum pressure change per pump ranged from 0.39 mmHg (Orbis-Sigma valve) to 23.1 (PS Medical LP Reservoir).

View Article: PubMed Central - HTML - PubMed

Affiliation: Academic Neurosurgical Unit, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK. apb49@cam.ac.uk <apb49@cam.ac.uk>

ABSTRACT

Background: It has been reported that pumping a shunt in situ may precipitate a proximal occlusion, and/or lead to ventricular over-drainage, particularly in the context of small ventricles. In the laboratory we measured the effect of pumping the pre-chamber of hydrocephalus shunts on intracranial hypotension.

Materials and methods: A simple physical model of the CSF space in a hydrocephalic patient was constructed with appropriate compliance, CSF production and circulation. This was used to test eleven different hydrocephalus shunts. The lowest pressure obtained, the number of pumps needed to reach this pressure, and the maximum pressure change with a single pump, were recorded.

Results: All models were able to produce negative pressures ranging from -11.5 mmHg (Orbis-Sigma valve) to -233.1 mmHg (Sinu-Shunt). The number of pumps required reaching these levels ranged from 21 (PS Medical LP Reservoir) to 315 (Codman Hakim-Programmable). The maximum pressure change per pump ranged from 0.39 mmHg (Orbis-Sigma valve) to 23.1 (PS Medical LP Reservoir).

Conclusion: Patients, carers and professionals should be warned that 'pumping' a shunt's pre-chamber may cause a large change in intracranial pressure and predispose the patient to ventricular catheter obstruction or other complications.

No MeSH data available.


Related in: MedlinePlus