Correlation of O2C-device with cutometer and scar scales in evaluation of burn scars: a retrospective cohort study of scar elasticity and perfusion

Introduction: The O2C device (LEA Medizintechnik GmbH, Giessen, Germany), approved in 2002, provides non-invasive monitoring of microcirculatory parameters in tissues and organs. The measurement principle is a combination of laser Doppler spectroscopy to determine blood flow and velocity with white light spectroscopy to determine oxygen saturation and hemoglobin amount. Blood flow, one of the four microcirculatory parameters measured by the O2C device, has been used to assess burn scars und has been found to be higher in hypertrophic scars. However, limited research exists on the O2C device’s role in evaluating burn scars. Purpose: The purpose of this secondary analysis is to quantify and investigate the correlation between the measurements with O2C-Device and those with Cutometer and scar scale scores in the evaluation of burn scars. Methods: We conducted a secondary analysis of the patient cohort described in our previous retrospective clinical study. This study examined the elasticity and perfusion of burn scars after autologous split-thickness skin grafting or the application of the temporary wound dressing Suprathel at least one year after treatment. A total of 80 patients (72.3% male) with a mean age of 47.6 (+- 16.3) years, treated between 2013 and 2018, were enrolled between March and December 2019. Pearson’s correlation coefficient, canonical correlations, and stepwise regression analysis were used to assess relationships between measurements with O2C-Device and those with Cutometer and scar scale scores. Results: Statistical analysis revealed a lack of correlation between measurements obtained with the O2C device and those from the Cutometer and scar scale scores in the evaluation of burn scars, with a maximum Pearson’s correlation coefficient of r = 0.43. Among the microcirculatory parameters, only weak correlations were found, with the exception of blood flow and velocity. Sensitivity analyses confirmed that the observed correlations were not influenced by age, sex, scar location, or smoking. Conclusion: Our analysis showed a lack of correlation between measurements obtained with the O2C device and those from the Cutometer and scar scale scores in the evaluation of burn scars. The O2C device provides objective, reproducible measurements of microcirculation and perfusion in burn scars, offering valuable data for evaluating scar healing and functionality. The O2C device may potentially serve as an additional tool to provide more information in the assessment of burn scars. However, the clinical relevance of this information needs to be investigated in future research projects. Abbreviations: AU, Arbitrary units (chosen arbitrarily by the developer of the device); Fig., Figure; LDI, Laser Doppler perfusion imaging; LSPI, Laser speckle perfusion imaging; log, Natural logarithm; logit, logit transformation; lr, log ratio; Mean, Arithmetic mean; n, Absolute value of a number; OSAS, Observer Scar Assessment Scale; POSAS, Patient and Observer Scar Assessment Scale; PSAS, Patient Scar Assessment Scale; Q-Q plot, quantile–quantile plot; r, Correlation coefficient; rHb, Relative Hemoglobin amount; SD, Standard deviation; SO2, Oxygen Saturation of Hemoglobin SO2 (%); STSG, Split-thickness skin graft; Tab., Table; VSS, Vancouver Scar Scale.