Infrared optoelectronic volumetry, the ideal way to measure limb volume

Objectives: The aim of the study was to compare a novel infrared optoelectronic system (Perometer) of limb volume measurement with water displacement and two indirect measurement techniques. Design: A prospective experimental study. Methods: In 10 healthy male volunteers (20 limbs) we compared limb volume measurements obtained by water displacement, infrared perometry, the disc model method and the frustrum method. In a further 17 patients with swollen limbs due to lymphatic (9 limbs) or venous (11 limbs) disease, perometry was compared to the disc model method and the frustrum method only. Results: In normal limbs, mean ± S.D. limb volume using water displacement was 1802 ± 268 ml. Perometer values agreed almost exactly (1809 ± 262 ml, r = 0.97, variation ± 7% by limits of agreement) but both the disc (1923 ± 306 ml, r = 0.90, variation ± 14%) and frustrum (1905 ± 372 ml, r = 0.72, variation a 28%) methods significantly overestimated limb volumes (p < 0.05 (ANOVA, Fisher's Least Significant Difference). In diseased limbs perometer, disc method and frustrum method results were 2415 ± 995 ml, 2494 ± 969 ml, and 2413 ± 870 ml representing variation of ± 17% and ± 23% for disc method and frustrum method respectively compared to perometry. Conclusions: Perometry is a novel, extremely accurate and easy method for assessing limb volume. It provides more accurate results than traditional indirect measurement of limb volume and potentially is a very useful clinical and research tool.