(840) TCD Is a Reliable Screening Tool for Decreased Cerebral Blood Flow in Pediatric Neurocritical Care

Introduction: Transcranial doppler (TCD) provides a noninvasive means to detect decreased cerebral blood flow (CBF) using the Lindegaard ratio (LR); with LR > 3 being suggestive of vasospasm in adults with subarachnoid hemorrhage. Although LR > 3 is similarly applied in children as an indicator of decreased CBF, there are no formal assessments. Our goal was to determine if the LR > 3 could be used as an indicator of decreased cerebral blood flow in children with critical neurological conditions.

Methods: Children admitted to the PICU from 1/2020 to 5/2022 with a primary neurological diagnosis and had at least one TCD were included in this retrospective study. TCDs without reported LR, children on ECMO or admitted to the cardiac ICU were excluded. We collected demographics, primary diagnosis, time to TCD from admission, and LR values from TCD. Digital subtraction angiogram (DSA) or CT angiography (CTA) were the gold standard. We calculated sensitivity, specificity, positive and negative predictive values (PPV, NPV) of LR > 3 as an indicator of decreased CBF as compared to the gold standard. Results were reported in count (%) and median [IQR].

Results: 83 patients (mean age 6.6 +/- 7 years; male 53%) and 314 TCDs were included; with a median of 3.8 [1-4] TCDs per patient. The median time to first TCD was 2.5 [1.6-4.6] days after admission. 79 (25%) TCDs from 23 children had LR > 3, with a median of 4.4 [2.6-7.6] days from admission. Ruptured AVM (7, 30%) and CNS infection (7, 30%) were the most common diagnoses associated with LR > 3. Patients with traumatic brain injury or post-cardiac arrest did not have TCDs with LR > 3. Compared to the gold standard (DSA=23, CTA=13), LR > 3 had a specificity of 79% (15/19) and sensitivity of 65% (11/17) and associated PPV of 73% and NPV of 71%.

Conclusions: TCD can serve as a screening modality for decreased CBF in a variety of critical pediatric neurological conditions. LR > 3 can also be used as a cut-off value in children. CNS infection may be at risk for CBF changes; therefore, routine TCD monitoring should be considered.