Validity of single-point assessments for determining leg pulse wave velocity in sitting and supine positions

There has been a great deal of interest into the effects of prolonged sitting on lower limb vascular function. However, most studies use flow-mediated dilation which is technically challenging. A simpler technique is pulse wave velocity (PWV) which can be estimated at any single arterial site of interest using a number of different calculations (Bramwell-hill [PWV_BH ], β-stiffness index [PWV_β ] and blood flow [PWV_BF ]). Findings from this technique would be better inferred if they compare to a standard criterion 2-point PWV assessment. The current study used ultrasound to determine which estimation of single-point PWV is most valid. The criterion was traditional ECG-gated 2-point (superficial femoral [SF]-posterior tibialis [PT]) PWV. Single-point estimates were calculated at the SF and PT arteries in both supine and seated positions. Single-point PWV was considered valid if the aSEE was <1.0 m·s. Findings show that for both postural positions, the absolute standard error of estimates (aSEE) criterion of <1.0 m·s was not achieved in either the PT or SF arteries using any of the single-point PWV calculations. However, single-point calculations consistently demonstrated the lowest error at the SF artery using PWV_β in both supine (SF aSEE = 1.7 vs. PT 2.7 m·s) and seated (SF aSEE = 1.5 vs. PT 3.0 m·s) positions. All single-point ΔPWV (supine - seated) calculations were higher in sitting, with PWV_β having the closest agreement (ΔSF aSEE 1.7 m·s) to the 2-point criterion. Single-point PWV calculations do not directly reflect regional 2-point PWV. However, they are sensitive to change when moving from supine to seated positions.