Assessment of laser Doppler perfusion imager’s in vivo reliability: Can it be used for a prospective analysis?

The aim of this study was to assess the reliability of the laser Doppler perfusion imager (Lisca PIM 1.0; Lisca development, Linkoping, Sweden) for longitudinal analysis. We measured the skin blood flow under a biological zero condition at the forearm level in 84 patients enrolled in a 12 week prospective interventional trial. Since the biological zero is the background reading registered by the laser when blood flow has been occluded, any fluctuation of the measurements obtained under this condition can be attributable to the laser scanner’s variability rather than biological variation. After the blood flow of the arm was occluded and arrested by a pressure cuff, blood perfusion readings were taken before and after the iontophoresis of a 1% acetylcholine chloride solution and a 1% sodium nitroprusside solution at the beginning of the study and during the two follow-up visits. A total of 927 biological zero readings were recorded throughout the study. The coefficient of variation of these measurements was 15.7%±8.5%. We conclude that laser Doppler perfusion imaging is a reliable and reproducible technique to assess the skin blood flow for prospective study since the variability of the measurements depending on the instrument itself is low.