High inter- and intra-observer agreement for measuring tissue oxygenation of the plantar surface of the foot in healthy participants with the Hyperview®: A pilot study.

OBJECTIVES

The Hyperview® is a novel camera that applies hyperspectral imaging to project local concentrations of oxyhaemoglobin (OXY), deoxyhaemoglobin (DEOXY) and O-saturation (O2-SAT) in a map. In this pilot validation study, we assessed inter - and intra-observer agreement for measuring OXY, DEOXY and O2-SAT in healthy participants.

METHODS

The plantar region of the right foot was assessed with the Hyperview® in 50 healthy participants. Two consecutive pictures were taken by the same observer, followed by two images by a second observer. Measurements were performed without and with standardization (a static device for both the foot and the Hyperview camera). Inter- and intra-observer agreements were expressed as Intraclass Correlation coefficients (ICC) with their 95% confidence interval (CI). A score <0.40 indicates poor agreement, 0.40-0.59 fair, 0.60-0.74 good and 0.75-1.00 excellent agreement. Bland and Altman plots were also generated.

RESULTS

Without standardization, the ICC values between the observers for OXY, DEOXY and O2-SAT ranged from 0.70 to 0.83. The intra-observer agreement of both observers ranged from 0.36 to 0.83. With standardization, the ICC values between the observers ranged from 0.80 to 0.82 and intra-observer agreement varied from 0.75 to 0.92. Four Bland and Altman plots were generated of the measurements of OXY by observers 1 and 2.

CONCLUSIONS

When standardization is used, the Hyperview® camera is a reliable device with excellent intra- and inter-observer agreements for the assessment of OXY, DEOXY and O-SAT. In future research, the inter- and intra-observer agreements of the camera should be investigated in patients with diabetes and/or peripheral arterial disease.