Use of the Air Plethysmograph in the Evaluation and Treatment of Patients with Venous Stasis Disease

BACKGROUND Some patients with venous stasis disease require physiologic testing of venous function for complete evaluation prior to and/or after treatment. OBJECTIVE To review basic uses of the air plethysmograph in evaluating patients with venous stasis disease. METHODS The air plethysmograph can be used to quantitate obstruction, reflux, and the effectiveness of the calf muscle pump. RESULTS Significant outflow obstruction is indicated by an outflow fraction of less than 35%. A venous filling index of 2 ml/ second or greater indicates significant reflux. An ejection fraction of less than 40% is associated with poor calf muscle pump function. CONCLUSIONS The air plethysmograph can be used in the evaluation of patients with venous stasis disease to quantify venous abnormalities of obstruction, reflux, and poor muscle calf pump function.