Effects of shortening distal shunt catheters in children as relates to patient age and valve type: a simulation study with clinical implications.

Objective: In children treated with a ventriculoperitoneal shunt (VPS), the growing body length increases the negative hydrostatic pressure within the shunt. At initial shunt insertion in neonates, infants, and small children, some surgeons traditionally shorten the distal catheter, although full length is generally well tolerated. Authors of this study investigate the effect of shortening distal shunt catheters on intracranial pressure (ICP) and cerebrospinal fluid (CSF) drainage rates in a bench test model set for different ages and with particular valve types.

Methods: Using a hardware-in-the-loop test bench, three different VPS settings were evaluated with both a standard 120-cm-long distal catheter and a short distal catheter (SDC) of 60 cm: a miniNav differential pressure valve with a 10-cmH2O opening pressure (MN10) and adjustable proGAV valves with a 25-cmH2O gravitational unit set at 5-cmH2O (PG5) and 10-cmH2O (PG10) opening pressures. The hardware was adjusted for the body length of 1-, 5-, and 10-year-old children. The software simulated the age-adapted physiological conditions of intracranial and intra-abdominal pressures. All valve and catheter combinations were tested 5 times, each in 1-hour runs in three positions: first horizontal, vertical, and second horizontal. Flow through the VPS and intracranial pressure were measured.

Results: The use of an SDC, as compared to the standard catheter, led to a significant ICP decrease in the vertical position using the PG5 across all age groups, PG10 for 5 year olds, and MN10 for 10 year olds. Using the SDC also resulted in a significantly higher drained CSF volume in the vertical position across all age groups with the MN10 and PG5.

Conclusions: Shortening the distal catheter leads to increased drainage rates with significant ICP decreases in a 1-year-old child model setup. This effect is more pronounced for low opening pressure valves, unprotected valve systems, and model setups for older children. These results suggest that an SDC may promote overdrainage of variable magnitude depending on the age and height of the child and the valve setting. Therefore, an SDC should be avoided.