Blood pressure in neonatology

Blood pressure (BP) assessment in the NICU remains controversial because both measurement reliability and the physiological meaning of a given value are context dependent. Systolic, diastolic and mean blood pressure should be put into context. Similarly, method of evaluation (invasive or non-invasive) and location of evaluation should be considered. Oscillometric readings are influenced by cuff size, measurement site and infant activity, while invasive measurements require appropriate transducer positioning and assessment of waveform quality. The commonly used definition of hypotension as mean blood pressure (MBP, in mmHg) below gestational age (GA, in weeks) is a pragmatic convention with limited validation as a threshold for circulatory compromise or treatment benefit. MBP reflects the interaction between systemic blood flow and vascular resistance: low pressure may coexist with adequate flow when resistance is low, whereas vasoconstriction can preserve apparently normal pressure despite reduced flow and impaired tissue perfusion, as occurs in compensated shock. Consequently, an MBP above GA does not exclude inadequate oxygen delivery, and an MBP below GA does not establish it. This distinction is particularly relevant during neonatal transition, when placental separation, falling pulmonary vascular resistance, changing ventricular loading conditions and persistent fetal shunts rapidly alter the relationship between pressure, ventricular output and effective systemic flow. A fixed GA-based threshold also overlooks postnatal age, individual autoregulatory capacity and the influence of local vascular resistance and venous pressure on organ perfusion. Oxygen delivery additionally depends on haemoglobin concentration and arterial oxygen saturation relative to metabolic demand. BP should therefore be interpreted alongside its trajectory, clinical perfusion findings, biochemical trends and targeted echocardiographic assessment where available. Treatment should address the underlying physiological disturbance and support adequate tissue perfusion, since increasing MBP alone does not establish that flow or oxygen delivery has improved.

Mean blood pressure (MBP) represents the arterial pressure averaged over a cardiac cycle, corresponding to the area under the arterial pressure waveform divided by the cycle duration. It therefore depends on the systolic pressure profile, the rate and extent of diastolic pressure decay, and the relative durations of systole and diastole, reflecting the combined effects of ventricular ejection, arterial compliance and vascular resistance.

Populational-based blood pressure by EPIQ-CNN

Blood Pressure Values by Gestational Age (at birth) for Day One of Age

Blood Pressure Values by Corrected Post Conceptional Age - To be used after Day 1 of life

Erasmus MC Blood Pressure Reference Values

Calculator here: https://neopeds.academy/bp/ 

Treatment of “isolated hypotension” of the very low birth weight (VLBW) infant is controversial as some studies indicate increase intraventricular hemorrhage (IVH) and no change in mortality (Dempsey et al. 2009). HIP trial (Dempsey et al. 2021) did not show any difference with the use dopamine but was terminated prematurely. As such, to avoid iatrogenic and without any indication that this leads to tissue ischemia, we do not recommend active interventions, but rather watchful assessments of ongoing perfusion.

Reference commentary on neonatal BP: https://ronlitman.substack.com/p/blood-pressure-in-neonates-what-is