tokens: Rv was 7 . 7 + / - 1 . 4 mmHg . ml - 1 . min . 100 g - 1 and Cv was 0 . 59 + / - 0 . 25 ml / mmHg , tau v calculated from the product of Rv and Cv was 4 . 20 + / - 1 . 58 s and from the ratio of delta V to delta Q was 4 . 95 + / - 1 . 53 s ( P = NS ) at a mean Pel of 17 . 6 + / - 3 . 7 mmHg . delta V was also produced by changing Pv ; the average tau v ( 1 . 95 + / - 0 . 37 s ) , was shorter than that with changes in flow .