Profiling oxygenation and microcirculation in healthy newborns at high altitude in the Andes reveals an increase in total vessel density: EAPS-0567

Background and aims: The developing human fetus copes well with the physiological reduction in oxygen supply in utero. The fetus of a pregnant woman residing at high altitude successfully adapts to greater hypoxic exposure compared to a fetus growing at sea level.
Methods: Fifty-three healthy term newborns in Puno, Peru (3840m above sea level) were studied within 24 hours after birth. Pre- and post-ductal arterial oxygen saturation (SpO2) were determined. Cerebral tissue and calf mus-
cle regional SO2 (rSO2) using near infrared spectroscopy (NIRS) were measured. Skin microcirculation using incident dark field (IDF) imaging (CytoCam®) were measured in this group and in a Dutch control group of 33 healthy term infants born at sea level.
Results: Pre- and post-ductal SpO2 in babies born at high altitude was 88.1% and
88.4%, being respectively 10.4% and 9.7% lower than newborns at sealevel (p<0.001). Cerebral and calf muscle rSO2 was significantly lower in
high altitude babies (cerebral 71.0 % vs. 74.9%; calf muscle 68.5% vs. 76.0%, p<0.001). Total vessel density (TVD) in high altitude newborns was 14% higher compared to babies born at sea level (29.7 vs. 26.0 mm/mm2; p≤ 0.001). Morphometric analysis of the microcirculation revealed that this difference was due to a significant increase in vessels with a diameter ≤20 μm. This increase in TVD was independent on the new-borns’ ancestry being either Andean, mixed or non-Andean.
Conclusions: Our data show that microvascular density is elevated in neonates born to mothers living at high altitude compared to babies born at sea level, independent of the neonates’ ethnicity.