This study evaluates a new, non-invasive device (Boppli™) that continuously measures blood pressure in newborn infants. The study compares Boppli measurements to standard blood pressure cuff measurements to determine how well the device works and whether it improves identification of high blood pressure in infants in the neonatal intensive care unit (NICU). The study also includes follow-up through 1 year of age to understand longer-term outcomes.

High blood pressure in newborn infants (neonatal hypertension) is increasingly recognized but remains difficult to diagnose. There is no single standard definition, and current blood pressure measurements rely on intermittent cuff-based methods. These cuff measurements can be affected by infant movement, agitation, and measurement technique, which may lead to inaccurate classification of blood pressure.

The Boppli™ device is a non-invasive monitoring system that uses a soft band placed on the infant to continuously measure blood pressure using pulse wave signals. Unlike standard cuffs, the device does not inflate and may reduce measurement-related variability.

This is a prospective observational study conducted in infants admitted to the NICU who are less than 5 kg and are at risk for high blood pressure or have clinical concern for elevated blood pressure. The study does not change clinical care, and Boppli measurements will not be used for medical decision-making.

The study has three parts:

Part 1: Feasibility and Comparison of Measurements Infants will wear the Boppli device for up to 72 hours while standard blood pressure cuff measurements are collected as part of routine care. Measurements from the two methods will be compared to evaluate how closely they agree. The study will also assess how easy the device is to use and how well it is tolerated by infants, families, and clinical staff.

Part 2: Effect of Cuff Measurements on Blood Pressure Infants will continue Boppli monitoring for 72 hours. Blood pressure cuff measurements will be obtained during the first 24 hours, stopped during the second 24 hours, and resumed during the third 24 hours. This design allows the study team to evaluate whether cuff measurements themselves affect blood pressure readings. The ability of the Boppli device to identify high blood pressure will be compared to cuff-based definitions.

Part 3: Follow-up After Hospital Discharge (Exploratory) Infants with concern for high blood pressure during hospitalization will be followed through 1 year of age. Blood pressure, growth, and clinical outcomes will be collected from routine clinic visits or study visits. This part of the study will evaluate whether early blood pressure findings persist and whether infants require treatment.

The main outcome of the study is whether the Boppli device can be used successfully in the NICU and how well its measurements agree with standard cuff measurements. Additional outcomes include how accurately the device identifies high blood pressure and whether cuff measurements influence blood pressure readings. Longer-term outcomes will describe blood pressure patterns and clinical care during infancy.

This study is considered minimal risk. The device is non-invasive, and participation will not affect the medical care infants receive.

Inclusion Criteria:

• Admitted to the neonatal intensive care unit (NICU)
• Age 0 to 9 months at time of enrollment
• Weight less than 5 kg
• At risk for elevated blood pressure or with clinical concern for hypertension, -including but not limited to:
• History of acute kidney injury or kidney disease
• History of extracorporeal membrane oxygenation (ECMO)
• Parent or legal guardian able to provide informed consent

Exclusion Criteria:

• Currently receiving extracorporeal membrane oxygenation (ECMO)
• Currently receiving any form of extracorporeal dialysis (e.g., continuous renal -replacement therapy)
• Presence of a ventricular assist device
• Congenital anomalies or clinical conditions that prevent placement of the Boppli™ device
• For Part 2 only: infants not expected to survive hospitalization

Care teams and providers will be aware of the infant's participation, as the Boppli device will be visible. However, as the Boppli measurements will not be used to impact clinical care, the device screen will be covered to minimize distraction. Nursing staff will periodically confirm proper connection and functioning of the device, without removing the screen cover except as necessary. The devices waveform is visible to ensure measurements are taken.