The use of a non-invasive neuromonitoring device in the emergency department: comparison with computed tomography results

Computed tomography (CT) is widely used to evaluate emergency department (ED) patients with headache, increasing costs, radiation exposure, and workload. Non-invasive intracranial pressure waveform (ICPW) monitoring has been proposed as an adjunctive triage tool. We assessed its diagnostic performance for identifying abnormal head CT findings in ED patients with red-flag headaches and explored potential resource implications. This retrospective study included 84 patients with red-flag headaches at Hospital Leforte Morumbi, Brazil (June-September 2023). All underwent non-invasive ICPW monitoring (brain4care System) and head CT during the same ED encounter. ICPW was abnormal if P2/P1 ≥ 1.2 or time-to-peak (TTP) ≥ 0.3. Sensitivity, specificity, positive and negative predictive values (PPV, NPV) were calculated against abnormal CT. CT expenditure and ED length of stay were assessed as exploratory outcomes. ICPW showed 90.0% sensitivity, 66.2% specificity, 98.0% NPV, and 26.5% PPV for abnormal CT. Median P2/P1 ratio yielded an ROC AUC of 0.778 (95% CI 0.640-0.900). Forty-nine patients (58.3%) had both normal ICPW and normal CT; their median ED stay was 3.5 h shorter than that of the overall cohort, though causality cannot be inferred. One patient had normal ICPW despite abnormal CT. Hypothetically, the normal examinations represented a projected gross CT expenditure of US$34,300. The high NPV supports further investigation of ICPW as an adjunctive risk-stratification tool, but the retrospective single-center design, small sample, and few abnormal CTs preclude definitive conclusions. ICPW should not replace clinical assessment or neuroimaging; resource implications remain exploratory hypotheses requiring prospective, multicenter validation.