Venous assessment using air plethysmography: a comparison with clinical examination, ambulatory venous pressure measurement and duplex scanning

Air plethysmography was compared with clinical assessment, ambulatory venous pressure measurement and duplex ultrasonography in 103 unselected limbs with venous disease and ten normal control limbs without such disease. Measurements of venous function obtained by air plethysmography showed considerable overlap between groups of limbs classified on the basis of clinical condition or by the presence of popliteal incompetence detected by duplex scanning. The measurement of venous refilling time using air plethysmography correlated poorly with that obtained by venous cannulation (rs = 0.58). The residual volume fraction did not correlate with ambulatory venous pressure measurement (rs = 0.04). Air plethysmography was not found to be as useful as previously reported. The residual volume fraction should not be accepted as a substitute for ambulatory venous pressure measurement, which remains the 'gold standard' test of venous function.