Smartphone pupillometry to predict hematoma expansion in Hemorrhagic stroke patients: A protocol for prospective cohort study

Introduction: Hematoma expansion is a main cause of early worsening after spontaneous intracerebral hemorrhage (ICH). Many hospitals in low income countries have no invasive pressure monitoring and no automated pupillometer. Staff use the Glasgow Coma Scale (GCS) and a penlight to check the pupils, and pupil changes seen with a penlight usually come late. The speed of pupil constriction may change earlier, and smartphones record video fast enough to measure it. Methods and analysis: This will be a single-centre prospective cohort study of 120 adults with ICH on non-contrast computed tomography (NCCT) who arrive within 24 hours of symptom onset. At admission and every 6 hours until 48 hours, we will record a 6 second smartphone video of each eye reacting to a flash, using an eyecup that blocks ward light. Open-source software will measure the pupil diameter in every frame. The main measure is constriction velocity (CV). The primary outcome is hematoma expansion (an increase of more than 6 mL or more than 33%) on NCCT at 24 hours. Secondary outcomes are a fall of 2 or more GCS points within 48 hours and in-hospital death. The primary analysis estimates the area under the receiver operating characteristic curve for the percentage fall in CV from each patient's first recording. Ethics and dissemination: Patients or their legal representatives will give written consent. Results will be submitted to a peer-reviewed journal, and the analysis code will be made public.