Comment to: Volume displacements from an incompetent great saphenous vein during a standardised Valsalva manoeuvre, by Lattimer CR, Kalodiki E, Azzam M, Geroulakos G. Acta Phlebologica 2012;13:25-30.

Reflux duration longer than 0.5 s is the cut-off point for the diagnosis of valvular incompetence. It is induced by a calf compression/release maneuvre (CCRM) in a weight-loaded position, with a full venous reservoir. CCRM is a pre-valve challenge test; reflux stops when the reservoir is full. In contrast, a Valsalva maneuvre (VM) is a post-valve challenge test and also a validated technique to induce reflux. It is performed in a supine position, when the venous reservoir is only partially filled. The Authors measured the volume of blood displaced during a standardized VM within an incompetent GSV (18 patients C2, reflux until the popliteal crease). A standard VM was performed by taking a deep breath during 3 s, a strain during the next 3 s, and then a relaxation during the final 3 s. GSV diameters during stain and relaxation were measured just distal to the SFJ. Volume flow in cc/min (time average mean velocity x diameter) multiplied by 3/60 gave volume displacement in 3 s. A median of 25 mL blood was displaced into the GSV over 3 s during straining with only 9 mL blood out of the GSV during the following 3 s of relaxation. As far as the volume is concerned, the different physical properties of foam must be referred to and the displaced foam volumes are likely to be lower. During ultrasound guided foam sclerotherapy (UGFS), VM is unavoidable (leg movements, cough, head lifting, strains, stocking application) and bolus displacement of foam into deep veins, and blood/foam mixing may cause concern over safety and efficacy. Protocols should be formulated to minimize the VM risks (stocking application, avoid standing, talking and coughing soon after the injection). Putting on a below-the-knee stocking before the procedure may be of benefit. This study has also shown that reflux duration following a VM can be determined by the physician and not by the pathology of the disease.