Back a bazillion years ago when I was writing the original manual for the Parks Flo-Lab I had the same question. Here is the answer that I found:

Cuff and Limb Circumference

Although von Recklinghausen recognized as early as 1901, the importance of an optimal cuff/limb circumference relationship, it is only recently that attention has begun to be given to this commonly neglected source of error. Alexander and coworkers, 1977, analyzed this relationship from a mathematical as well as an experimental viewpoint. They confirmed the empirically established recommendation - 1.2 x arm-circumference width - of the American Heart Association Committee, 1939, 1967. In addition, they concluded that it is preferable to encircle the arm completely with the bladder rather than only partially.

Finally, they concluded that once the 1.2 x arm-circumference width is reached, no additional error is introduced when the width is increased.

At the other end of the cuff-size spectrum are the bladder sizes used in the measurement of toe and digital pressures. On the basis of his studies in 1971 and 1972, Gundersen recommends a toe cuff size of 2.4 cm, although this width may make it difficult to accommodate the cuff and the sensor on some toes. Various authors recommend cuff sizes between 20 and 24 mm. The 24 mm cuff is recommended for the great toe, and for all other toes a 20 mm width is suggested.

Noninvasive Diagnostics in Vascular Disease, Fronek, 1989, pg. 4

Hope that helps.

John Logan RVT
Technical Director
Noninvasive Vascular Laboratory
Johns Hopkins Bayview Med Ctr
410-550-6608

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