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

Abstract

Objectives

The Hyperview® is a novel camera that applies hyperspectral imaging to project local concentrations of oxyhaemoglobin (OXY), deoxyhaemoglobin (DEOXY) and O₂-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 O₂-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.