Cutaneous microcirculation in preterm neonates: Comparison between sidestream darkfield (SDF) and incident darkfield (IDF) imaging

Background and aims: The Cytocam is a new generation Incident darkfield imaging (IDF) based handheld microscope for bedside visualization and quantification of microcirculatory alterations. The Cytocam may be viewed as a technolocigal successor of the sidestream darkfield imaging (SDF) device, currently the most used device for microcirculatory measurements. Aims: The purpose of this study is to validate its use in transcutaneous microcirculatory measurements in preterm neonates. We hypothesized that IDF imaging produces higher quality images in preterm neonates resulting in a higher computed vessel density. Methods: After written informed consent was obtained, skin microcirculation was consecutively measured on the inner upper arm with de SDF and IDF device. Images were exported and analyzed offline using existing software (AVA 3.0). Vessel density and perfusion was calculated using the De Backer Score (DBS) and proportion of perfused vessels (PPV). Results: were analyzed using the Wilcoxon signed ranks test. Results: In a heterogeneous group of sixteen preterm neonates (median GA 29 weeks, range 24 - 33,4) IDF imaging visualized 11% more vessels resulting in a significantly higher vessel density (DBS 16,0/mm vs. 14,3/ mm, p-value= 0.001). The perfusion of vessels could be determined more accurately in the IDF images, resulting in a significant lower PPV (88,6% vs. 94,0%, p-value= 0.003). Conclusions: IDF imaging of the cutaneous microcirculation in preterm neonates shows a higher vessel density and lower perfusion compared to the existing SDF device. With the additional technical features, the IDF Cytocam hand microscope promises to be a usefull clinical tool in the monitoring of the hemodynamically comporimised critically ill neonates.