Transcutaneous Bilirubinometry in Preterm and Term Newborn Infants before and during Phototherapy.

INTRODUCTION: To evaluate the accuracy of transcutaneous bilirubin measurement in a large population of newborn infants, before and during the phototherapy. PATIENTS AND METHODS: A single Bilicheck instrument was used for transcutaneous measurements. A photo-opaque patch was positioned over the measurement site prior to starting phototherapy. Transcutaneous bilirubinometry was conducted on an unpatched area of the forehead skin and on the nearby site covered by the photo-opaque patch. Readings were obtained from patched and unpatched areas and simultaneous total serum bilirubin concentrations were compared. RESULTS: We studied 134 term and 36 preterm newborns. Pre-phototherapy measurements showed a strong correlation (r: 0.929, P < 0.001, Limit of agreement: -1.8 to 3.1) between Bilicheck and serum bilirubin readings. Post-phototherapy correlation between Bilicheck and serum bilirubin readings was (r: 0.921, P < 0.001, LOA: -1.8 to 2.8) among term and (r: 0.887, P = 0.001, LOA: -1.4 to 2.7) among preterm neonates in patched areas. These correlations were (r: 0.666, P < 0.001, LOA: -1.7 to 7.3) among term and (r: 0.756, P < 0.001, LOA: -0.5 to 5.3) preterm neonates post-phototherapy in unpatched areas. CONCLUSION: BiliCheck can be safely used for the evaluation of bilirubin levels in preterm and term newborn infants under phototherapy. BiliCheck is slightly less reliable among preterm newborns.

Laser-heated emissive plasma probe.

Emissive probes are standard tools in laboratory plasmas for the direct determination of the plasma potential. Usually they consist of a loop of refractory wire heated by an electric current until sufficient electron emission. Recently emissive probes were used also for measuring the radial fluctuation-induced particle flux and other essential parameters of edge turbulence in magnetized toroidal hot plasmas [R. Schrittwieser et al., Plasma Phys. Controlled Fusion 50, 055004 (2008)]. We have developed and investigated various types of emissive probes, which were heated by a focused infrared laser beam. Such a probe has several advantages: higher probe temperature without evaporation or melting and thus higher emissivity and longer lifetime, no deformation of the probe in a magnetic field, no potential drop along the probe wire, and faster time response. The probes are heated by an infrared diode laser with 808 nm wavelength and an output power up to 50 W. One probe was mounted together with the lens system on a radially movable probe shaft, and radial profiles of the plasma potential and of its oscillations were measured in a linear helicon discharge.