The gestational age significantly affects peripheral perfusion index value in low‐altitude areas

Abstract

Newborn infants, especially those in the neonatal intensive care unit, tend to go through a transition period in early life including complex perfusion changes. Haemodynamic monitoring allows for early detection of diseases, thus improving outcomes and can be life-saving. A reliable modality of hemodynamic monitoring requires early, direct, non-invasive and continuous detection of irreversible damage caused by insufficient tissue perfusion and oxygenation. PPI has been embedded in the latest generation of pulse oximeters, which obtain data via a sensor attached to infants' palm or sole and emit 940 nm near-infrared light. Different tissues and blood vessels absorb different amounts of light, with the amount of light absorbed by pulsatile tissues-dynamic changes of arterial blood flow, and non-pulsatile tissues-venous blood, muscle and other tissues, being detected. The amount of light absorbed by non-pulsatile tissue is constant. PPI is the percentage of the former to the latter. 1 It reflects the real-time change of peripheral blood flow and is an evaluation of pulse intensity at specific monitoring sites. 2 In the newborn population, GA has a great impact on physiology. The early postnatal PPI values of newborns at different GAs may also be different. 1 Therefore, the range and thresholds of PPI values for detecting diseases in newborns should be modified according to different GA. 1 In addition, studies which investigated PPI were previously conducted at sea level but lacked data from other altitudes. 3