Reproducibility of the Pleth Variability Index in premature infants.

The aim was to assess the reproducibility of the Pleth Variability Index (PVI), developed for non-invasive monitoring of peripheral perfusion, in preterm neonates below 32 weeks of gestational age. Three PVI measurements were consecutively performed in stable, comfortable preterm neonates in the first 48 h of life. On each occasion, pulse oximeter sensors were attached to two different limbs for 5 min. Reproducibility was assessed with the intra-class correlation coefficient (ICC) and Bland-Altman analysis. A total of 25 preterm neonates were included. Inter-limb comparison showed fair to moderate ICC's with 95%-confidence intervals (95%-CI). Left hand-right hand ICC = 0.498, 95%-CI (0.119-0.753); right foot-right hand ICC = 0.314 (-0.088-0.644); right foot-left foot ICC = 0.315 (-0.089-0.628). Intra-limb comparison showed fair to moderate ICC for right foot-right foot ICC = 0.380 (-0.014-0.677); and good ICC for right hand-right hand ICC = 0.646 (0.194-0.852). Bland-Altman plots showed moderate reproducibility of measurements between different limbs and of the same limb in consecutive time periods, with large biases and wide limits of agreement. The findings from this study indicate that PVI measurement is poorly reproducible when measured on different limbs and on the same limb in stable and comfortable preterm neonates.

Pregnancy at high altitude in the Andes leads to increased total vessel density in healthy newborns.

The developing human fetus is able to cope with the physiological reduction in oxygen supply occurring in utero. However, it is not known if microvascularization of the fetus is augmented when pregnancy occurs at high altitude. Fifty-three healthy term newborns in Puno, Peru (3,840 m) were compared with sea-level controls. Pre- and postductal arterial oxygen saturation (SpO2) was determined. Cerebral and calf muscle regional tissue oxygenation was measured using near infrared spectroscopy (NIRS). Skin microcirculation was noninvasively measured using incident dark field imaging. Pre- and postductal SpO2 in Peruvian babies was 88.1 and 88.4%, respectively, which was 10.4 and 9.7% lower than in newborns at sea level (P < 0.001). Cerebral and regional oxygen saturation was significantly lower in the Peruvian newborns (cerebral: 71.0 vs. 74.9%; regional: 68.5 vs. 76.0%, P < 0.001). Transcutaneously measured total vessel density in the Peruvian newborns was 14% higher than that in the newborns born at sea level (29.7 vs. 26.0 mm/mm(2); P ≤ 0.001). This study demonstrates that microvascular vessel density in neonates born to mothers living at high altitude is higher than that in neonates born at sea level.

Adaptation of the Cutaneous Microcirculation in Preterm Neonates.

OBJECTIVE: Transition from fetal to neonatal circulation is characterized by multiple hemodynamic changes. The role of the microcirculation in this process is underexposed. Visualizing the cutaneous microcirculation can help us understand peripheral perfusion in a noninvasive manner. METHODS: Cutaneous microcirculation of term and preterm infants born below 32 weeks of GA was measured in the first month of life using IDF imaging. Linear mixed modeling was used to identify clinical variables which influence the cutaneous microcirculation. RESULTS: Sixty preterm and 33 term infants were included. TVD of preterm infants significantly decreased in the first month of life (31.7 mm/mm(2)  day 1 vs 27.9 mm/mm(2)  day 28), but remained significantly higher compared to TVD of term infants on day 1 (25.8 mm/mm(2) ). Besides postnatal age, no clinical variables were associated with TVD. Infants born SGA had significantly higher TVD values directly after birth than those born appropriate for GA (35.4 mm/mm(2) vs 31.6 mm/mm(2) ; p = 0.015). CONCLUSIONS: TVD decreases in the first month after birth and is higher in preterm infants compared to those born term. Differences in antenatal oxygen exposure might explain the adaptation of the microcirculation.

Reproducibility of microvascular vessel density analysis in Sidestream dark-field-derived images of healthy term newborns.

OBJECTIVE: Microcirculatory visualization has already been used to investigate buccal and cutaneous microcirculatory alterations in neonates. Still, the reproducibility of these microvascular measurements has never been studied in (premature) neonates. This study aimed to determine the reproducibility of microvascular vessel density in cutaneous and buccal SDF clips in one-day-old term newborns. METHODS: Buccal and cutaneous microcirculations were measured using SDF imaging. Vessel density was independently assessed by two investigators. Reproducibility was assessed from the ICC and Bland-Altman analysis. RESULTS: Reproducibility of vessel density assessment in the buccal area was good, with ICCs for total and PVD of 0.93 (0.88-0.97) and 0.93 (95% CI 0.85-0.97), respectively, and a near zero bias and acceptable limits of agreement in the Bland-Altman analysis. Reproducibility of assessment of the cutaneous microcirculation was poor with ICCs for total and PVD of 0.31 (0-0.70) and 0.37 (0-0.74), respectively, and large biases (3.09 and 2.53) in the Bland-Altman analysis. CONCLUSIONS: Evaluation of buccal microvascular vessel density in SDF-derived images in term newborns is reproducible in contrary to the cutaneous vessel density.