Orthogonal Polarization Spectral Imaging (OPS) Measurements of Microcirculatory Changes in Term Newborns with Suspected Infection

The early diagnosis of neonatal infection remains a challenge. Recent studies using Optical Polarized Spectral (OPS) imaging techniques, have reported microcirculatory alterations in adult patients with severe sepsis and septic shock. The objective of this study was to compare microcirculatory flow and vascular density between healthy controls and sick newborns with neonatal infection. OPS images were obtained prospectively from the vascular bed of ear conch and upper arm of 47 newborns on their 1st, 2nd and 3rd day of life. Infection was defined as IL-6 >50pg /mL and CRP >0,5 mg /dL. OPS sequences were analyzed off-line, blinded to clinical status of the infant with a semi-quantitative method based on the works of Sakr (46) and Boerma (47). Flow was examined differentiating between no flow, intermittent, sluggish and continuous flow. All vessels that did not have a continuous flow were classified as pathologic and their percentage was determined. Vascular density of the sequences was also calculated. Sixteen infants developed an infection. Most episodes of infection were not severe. Microcirculatory data was analyzed and tested with a non parametric test. The images obtained from ear showed a better image quality and an easier performan¬ce than those from upper arm in term newborns (infection: 32%, 95% confidence interval [19-44] vs. healthy: 10% [6-13]; p= 0.0003). Despite a tendency to higher percent of impaired flow, the microcirculatory flow in arm did not reach a statistical significance when comparing both groups (infection: 19% [16-25] vs. healthy: 13% [10-11]; p= non significant). A trend to lower vascular density was observed in the sequences obtained from ear in the infected group but not in those obtained from arm. Both places did not show a statistical difference. It can be concluded that ear conch is a better site to study the microcirculation in term newborns than the arm. In the ear conch even in infants with mild to moderate signs of infection, microcirculatory flow is impaired in a large proportion of vessels early in the course of disease. Since these changes can be easily recognized at the external ear, an on-line evaluation of microcirculatory flow could be an important screening tool for infection in the future