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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

The laboratory rig used to test the pumping actions of hydrocephalus shunts including model of CSF compensation.
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Figure 1: The laboratory rig used to test the pumping actions of hydrocephalus shunts including model of CSF compensation.

Mentions: To model the cerebrospinal fluid (CSF) space, a wide-necked feeding bottle (270 ml, Boots, UK) was filled with de-aerated de-ionised water to mimic CSF (Fig. 1). A latex membrane (0.14 mm thick, diameter 4 cm) was placed over the top of the bottle and under the cap. A compliant system was created by making a 2 cm diameter hole in the cap. The fluid forced the membrane through the hole and the size of the hole determined the magnitude of the compliance. The model also included a resistance to CSF reabsorption in the form of a lumbar puncture outflow needle, giving a resistance to CSF flow of 7.4 mmHg ml-1min-1, within the 6–10 mmHg range found in humans [13,14]. To mimic CSF production, fluid was infused at a constant rate of 0.3 ml min-1. The shunt to be tested was attached to the model using 10 cm of low resistance tubing, mimicking a ventricular catheter. An outflow of the same tubing (80 cm long and 1.2 mm ID) mimicked the peritoneal catheter.


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)

The laboratory rig used to test the pumping actions of hydrocephalus shunts including model of CSF compensation.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: The laboratory rig used to test the pumping actions of hydrocephalus shunts including model of CSF compensation.
Mentions: To model the cerebrospinal fluid (CSF) space, a wide-necked feeding bottle (270 ml, Boots, UK) was filled with de-aerated de-ionised water to mimic CSF (Fig. 1). A latex membrane (0.14 mm thick, diameter 4 cm) was placed over the top of the bottle and under the cap. A compliant system was created by making a 2 cm diameter hole in the cap. The fluid forced the membrane through the hole and the size of the hole determined the magnitude of the compliance. The model also included a resistance to CSF reabsorption in the form of a lumbar puncture outflow needle, giving a resistance to CSF flow of 7.4 mmHg ml-1min-1, within the 6–10 mmHg range found in humans [13,14]. To mimic CSF production, fluid was infused at a constant rate of 0.3 ml min-1. The shunt to be tested was attached to the model using 10 cm of low resistance tubing, mimicking a ventricular catheter. An outflow of the same tubing (80 cm long and 1.2 mm ID) mimicked the peritoneal catheter.

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