Prediction of Intraventricular Hemorrhage Using Echocardiography and Near Infrared Spectroscopy

Overview

Moderate-severe intraventricular hemorrhage (msIVH, Grades II-IV) is a significant neurological complication among extremely low gestational age neonates (ELGANs, \<=27+6 weeks) and is associated with long-term neuro-disabilities. In Canada, msIVH affects \~25-30% of the 1300 ELGANs born annually, with little change in incidence over last decade. Typically, it occurs between days 2-7 of age, providing a finite window of opportunity. Instituting therapies at the population level, however, exposes many low-risk infants to side effects, adversely affecting risk-benefit profile and requiring large sample sizes in trials. A targeted preventative approach, though ideal, is currently challenged by our inability to reliably identify at-risk ELGANs early after birth. Near-infrared spectroscopy (NIRS) has emerged as a promising non-invasive bedside neuromonitoring tool. Pilot studies using NIRS, including ours, found lower cerebral saturations (CrSO2) and greater periods of altered cerebral autoregulation in infants who later developed msIVH. However, a systematic planned investigation is needed to establish the predictive characteristics of NIRS-derived markers, using clinically translatable methods (cumulative burden over time-period vs. single time-point values) and identify their relative performance at different time-points during transition. Further, incorporating echocardiographic (ECHO) hemodynamic markers, known to be associated with msIVH, may allow for the establishment of robust multi-model prediction models and the gain of mechanistic hemodynamic insights to inform future management. Hence, our objective is to investigate the utility of multi-modal assessment using NIRS and ECHO for early identification of ELGANs at risk of msIVH, and generate clinically applicable predictive model(s).

The overall objective is to conduct a large, adequately powered prospective cohort study to investigate the utility of combined hemodynamic assessment using NIRS and ECHO for early identification of ELGANs at risk of developing moderate-severe IVH, and to establish clinically translatable prediction models. The specific primary aim is to examine the discriminating characteristics of NIRS-derived parameters (CrSO2 and cerebral oxygenation index \[COIx, values \>0.5 indicate altered cerebral autoregulation\]) at 12, 18, 24, 30, 36, 42 and 48 hours of age, individually and in combination, for identifying ELGANs who subsequently develop moderate-severe IVH. The postnatal age where NIRS may best identify at-risk ELGANs is unknown and identifying these infants early within 48 hours of age may maximize its impact for employing neuroprotective strategies. The secondary aims are: 1. To examine if adding ECHO parameters of systemic blood flow (left ventricular output \[LVO\], superior vena cava \[SVC\] flow and PDA size) and patient demographics can improve the discriminating characteristics of NIRS and generate relevant clinical prediction models. 2. To gain mechanistic insights into pathophysiology of moderate-severe IVH, by examining associations between significant abnormalities on NIRS, as identified and ECHO markers which may impact cerebral perfusion and oxygen delivery (PDA and its size, LVO, right ventricular output and left ventricular ejection fraction). This will be novel information as potential mechanisms governing low CrSO2 or altered autoregulation in ELGANs are not known and can potentially inform future clinical preventative strategies and help design interventional trials.