Inline flow sensor for ventriculoperitoneal shunts: Experimental evaluation in swine

Shunts are commonly employed to treat hydrocephalus, a severe central nervous disease caused by the buildup of cerebrospinal fluid in the brain. These shunts divert excessive cerebrospinal fluid from brain ventricles to other body cavities, thereby relieving the symptoms. However, these shunts are highly prone to failure due to obstruction from cellular debris, leading to cerebrospinal fluid accumulation in the brain and exacerbation of neurological symptoms. Therefore, there is a clinical need for a reliable, non-invasive method of monitoring shunt performance. Recently, a simple inline flow sensor was reported for monitoring ventriculoperitoneal shunting of cerebrospinal fluid in hydrocephalus treatment. The present work aimed to evaluate performance of the device in an animal model of hydrocephalus. Sensor-equipped shunt tubes were placed in anesthetized, juvenile swine. The flows reported by the sensor were compared with gravimetric flow measurements. Robust correlations (r ≈ 0.87-0.96) between the gravimetric and sensor-reported flows were obtained in 4 of the 6 experiments. The mean slope of the linear relationship of the gravimetrically determined vs. sensor flow rates was 0.98 ± 0.09 in the 6 experiments, indicating the sensor accurately reported shunt flows up to 35 ml/h. The sensor responded immediately to abrupt flow changes following cerebroventricular fluid injections. Minor hardware problems were identified and corrected. These experiments provide practical guidance for future preclinical testing of the device.