Innovative Application of Point of Care Ultrasound in Assessing Ventriculo-Peritoneal Shunt Patency

Current techniques to detect obstruction of ventriculo-peritoneal (VP) shunts are costly, invasive, and time-consuming. This study examines the efficacy of using point-of-care ultrasound (POCUS) to identify shunt nonpatency.

We conducted a single-center observational cohort study on patients with medium-pressure VP shunts for hydrocephalus. POCUS was used to evaluate shunt patency, and the results were compared with computed tomography/MRI/trans-fontanelle ultrasound evaluations for hydrocephalus.

Among the 39 patients studied, 17.9% had shunt obstructions. Patients with obstructed shunts, on comparison with patent shunts, had higher optic nerve sheath diameter (ONSD): 4.3 ± 0.2 mm vs 4.1 ± 0.2 mm (P = .014), with an area under the curve (AUC) of 0.750 (95% CI 0.531-0.969), lower cerebrospinal fluid (CSF) flow velocity: distal to the chamber: 3.1 ± 2.9 cm/s vs 9.8 ± 3.1 cm/s (P = .000), with an AUC of 0.915 (95% CI 0.825-1.000) and proximal to the chamber: 3.3 ± 3.1 cm/s vs 8.9 ± 2.7 cm/s (P = .000), with an AUC of 0.906 (95% CI 0.810-1.000), and absence of free fluid in the peritoneal space (P = .000). Using the cutoff values obtained from the AUC analysis, raised ONSD ≥4.25 mm, CSF flow distal to the chamber ≤6.15 cm/s, CSF flow proximal ≤6.85 cm/s, and absence of free fluid in the peritoneal cavity predicted shunt nonpatency with 100% sensitivity and 100% negative predictive value (NPV, odds ratio 1.583 [95% CI 1.123-2.232, P = .003]). Even when excluding raised ONSD, the sensitivity and NPV remained 100% (odds ratio 1.875 [95% CI 1.168-3.010, P = .000]).

Our study supports the novel use of POCUS for detecting sonological signs of VP shunt nonfunction with very high sensitivity and NPV. This technique is quick, safe, and cost-effective, making it an excellent option for outpatient surveillance of VP shunt obstruction.