A comparison of the strain-gauge and the Dohn air-filled plethysmographs for blood flow measurements in the human calf.

Blood flow measurements using either a strain gauge plethysmograph or the Dohn air-filled plethysmograph were compared by means of successive measurements in the calf in six normal subjects (12 extremities) and in five patients with arterial insufficiency (nine extremities). Flows were recorded during rest as well as after 5 minutes of ischemia. The strain-gauge plethysmograph tended to give lower values than the Dohn plethysmograph, although at higher flow rates the results were identical. It is concluded that, for most purposes, the Dohn plethysmograph can be replaced by the strain gauge plethysmograph, which is considerably simpler to use.