Cuff inflation time significantly affects blood flow recorded with venous occlusion plethysmography

Rehan T Junejo,Janice M Marshall,Clare J Ray

doi:10.1007/s00421-018-04056-8

Rehan T Junejo, Janice M Marshall + Show 1 more

Open Access

https://doi.org/10.1007/s00421-018-04056-8

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Abstract

PurposeWe tested whether the values of limb blood flow calculated with strain-gauge venous occlusion plethysmography (VOP) differ when venous occlusion is achieved by automated, or manual inflation, so providing rapid and slower inflation, respectively.MethodIn 9 subjects (20–30 years), we calculated forearm blood flows (FBF) values at rest and following isometric handgrip at 70% maximum voluntary contraction (MVC) when rapid, or slower inflation was used.ResultRapid and slower cuff inflation took 0.23 ± 0.01 (mean ± SEM) and 0.92 ± 0.02 s, respectively, reflecting the range reported in published studies. At rest, FBF calculated from the 1st cardiac cycle after rapid and slower inflation gave similar values: 10.5 ± 1.4 vs. 9.6 ± 1.3 ml dl− 1 min− 1, respectively (P > 0.05). However, immediately post-contraction, FBF was ~ 40% lower with slower inflation: 54.6 ± 5.1 vs. 33.8 ± 4.2 ml dl− 1 min− 1 (P < 0.01). The latter value was similar to that calculated over the 3rd cardiac cycle following rapid inflation: 2nd cardiac cycle: 40.5 ± 4.5; 3rd cycle: 32.6 ± 4.5 ml dl− 1 min− 1. Regression analyses of FBFs recorded at intervals post-contraction showed those calculated over the 1st, 2nd, or 3rd cardiac cycles with rapid inflation correlated well with those from the 1st cardiac cycle with manual inflation (r = 0.79, 0.82, 0.79; P < 0.01). However, only the slope for the 3rd cycle with rapid inflation vs. slower inflation was close to unity (2.07, 1.34, and 0.94, respectively).ConclusionThese findings confirm that the 1st cardiac cycle following venous occlusion should be used when calculating FBF using VOP and, but importantly, indicate that cuff inflation should be almost instantaneous; just ≥ 0.9 s leads to substantial underestimation, especially at high flows.

Highlights

Venous occlusion plethysmography (VOP) is widely used for measuring limb blood flow: it is relatively inexpensive, non-invasive, and apparently simple to use
In view of evidence that forearm blood flows (FBF) should be calculated over the 1st cardiac cycle following cuff inflation, because FBF progressively decreases from the 2nd cardiac cycle onwards (Tschakovsky et al 1995; Wood and Stewart 2010), our primary objective was to compare FBF values calculated from the 1st cardiac cycle following slower and rapid inflation, using manual and automated inflation, respectively, to achieve this
Peak FBF following isometric contraction at 70% maximum voluntary contraction (MVC) was considerably less than that calculated with rapid inflation

Summary

Introduction

Venous occlusion plethysmography (VOP) is widely used for measuring limb blood flow: it is relatively inexpensive, non-invasive, and apparently simple to use. VOP rests on the assumption that when venous outflow is occluded, by inflating a cuff to a pressure higher than venous pressure, limb volume increases at a rate that reflects arterial inflow. Since arterial inflow gradually falls following venous occlusion as the veins fill, it was recommended in an early review (Greenfield et al 1963) and endorsed since (Joyner et al 2001; Wilkinson and Webb 2001) that blood flow be calculated from the initial rate of volume increase, generally over the first few cardiac cycles. VOP measurements were highly reproducible at rest and during reduced or increased blood flow, more reproducible than Doppler ultrasound (Roberts et al 1986; Pallares et al 1994; Thijssen et al 2005; Kooijman et al 2007)

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