Camera-based Monitoring of Heart Rate Variability for Preterm Infants in Neonatal Intensive Care Unit

Advancements in video health monitoring opened up new opportunities for contactless infant monitoring in the Neonatal Intensive Care Unit (NICU). Several studies have demonstrated the potential of heart rate variability (HRV) as an early warning measure for acute illnesses, such as late-onset sepsis and bradycardia. Conventional HRV analysis typically relies on electrocardiography (ECG) or contact photoplethysmography (contact-PPG) that may damage infants’ fragile skin. This study aims to investigate the feasibility of camera-PPG based HRV measurement for preterm infants in NICU, i.e. an important vital sign that was less studied in this scenario. A clinical study was conducted in two hospitals involving 41 infants, focused on comparing the HRV parameters obtained from camera-PPG and contact-PPG with the reference of ECG. Results show that camera-HRV has similar performance as contact-HRV in cases without motion distortions, and it has smaller errors and better robustness in the presence of motion distortions. Strong correlations can be observed between camera-PPG, contactPPG and ECG in several HRV parameters (Mean IBI, SDNN, LF, VLF, and SD2), though the performance on short-term variability parameters need to be improved further. The findings suggest that camera-PPG could be a promising tool for motionrobust HRV estimation in NICU, offering a potential surrogate for contact-PPG in early-warning of deteriorations of preterm infants.