The “Charge Efficiency Factor” compensates for the capacity (Ah) losses during charging. A setting of 100% means that there are no losses. The SmartShunt can also be connected to any device in the GX family including the Colour Control GX and the new Cerbo GX using an optional VE.Direct cable. This provides the GX device with battery data for system control – and there’s no need to find room for a BMV display.

The shunt is fitted in-line with theleisure/house battery's negative cable, the starter/auxiliary battery's negative cable is connected to the shunt's output and fused +ve supplies are takenfrom each battery into the shunt's 2 inputs. As an alternative to monitoringthe voltage of a2nd battery, the shunt's2nd/auxiliary inputcan be used for temperature monitoring (requires optional temperature sensor) or midpoint monitoring. The information from the SmartShunt can also be displayed on a GX device by connecting with a VE.Direct cable.Siphon resistive devices. (a) Membranous devices include a pressure sensitive membranous compartment. (b) Gravitational mechanisms include a mass-spring system that reacts to gravity and regulates the opening of a valve.

Hydrocephalus shunt technology: 20 years of experience from the cambridge shunt evaluation laboratory. J Neurosurg. 2014; 120( 3):697–707. [ PubMed] [ Google Scholar] The Codman Hakim Programmable Valve (CHPV), also known as the programmable Medos shunt, is a double spring ball valve, where the inlet valve controls the total pressure [ 13]. This specific section consists of a synthetic ruby ball depressed in the valve seat by a 316L flat stainless-steel spring. Opening pressure of the valve is adjusted by raising the spring on a spiral polyethersulfone staircase using the magnetic field from an external handheld apparatus [ 14]. The CHPV has a range of 30 to 200 mm H 2O, with incremental steps of 10 mm H 2O. To confirm the valve setting, plain skull radiography may be needed after shunt pressure adjustment. The Codman Hakim valve can withstand up to a 3 Tesla magnetic field, although the valve must be immediately readjusted after exposure to such a field to avoid complications such as a changed shunt setting from the magnetic interference or permanent disability of the valve [ 13]. In one documented study, the Medos valve behaved very well with one-third of the valves remaining fixed after being exposed to an external magnetic field of 1.5T from an MRI [ 15]. Despite this, the study conducted still found causes of concern as in 11 of 15 occasions, when valves were set to a starting value of 200 mm H 2O, the magnetic field induced by the MRI caused the flat spring of the valve to move across the top of the cam and fall to a level below 30 mm H 2O. A drastic reduction in the pressure setting from 200 mm H 2O to 30 mm H 2O could lead to siphoning of CSF and deleterious effects on the patient, such as subdural hematomas. One of the five Medos valves tested was no longer programmable after four test runs in the MRI. Attempts to reprogram the valve were conducted after 12 hours and 30 days, both of which failed to resolve the issue. The Strata valve also uses a ball and a magnetic rotor, as has been detailed for the Medos valve. With the Strata, there are only five adjustable pressure settings, and a setting is selected depending on the specific needs of the patient. The Strata solution includes preoperative and postoperative adjustment tools. With the locator tool and the indicator tool, both preoperative and postoperative tools follow the mechanism detailed in Figure 2. The postoperative tools, named StrataVarius, includes a digital display to allow noninvasive measurement of pressure. The Strata is approved for MRI usage, but patients must seek readjustment immediately after imaging to ensure valve pressure invariability.Transcutaneous pressure-adjustable valves and magnetic resonance imaging: an ex vivo examination of the codman-medos programmable valve and the sophy adjustable pressure valve. Neurosurgery. 1997; 40( 5):1050–8. [ PubMed] [ Google Scholar] A zero current calibration is (almost) never needed. Only perform this procedure in case the battery monitor shows a current while you are absolutely sure that there is no actual current flowing. The only way to be sure is to physically disconnect all wires and cables connected to the SYSTEM MINUS side of the shunt. Do this by unscrewing the shunt bolt and removing all cables and wires from that side of the shunt. The alternative, switching loads or chargers off, is NOT accurate enough as this does not eliminate small standby currents. Closing This parameter is used to tell the battery monitor how big the battery is. This setting should already have been done during the initial installation. The setting is the battery capacity in Amp hours (Ah). Evaluation of CSF flow in shunts using a non-invasive thermal technique. Cerebrospinal Fluid Res. 2009; 6 S1:S41. [ Google Scholar]