Venous occlusion plethysmography shows stronger short-term than one-week reliability for assessing forearm venous outflow, with measurements influenced by vessel length and gender.
Same-day venous occlusion plethysmography yields higher reliability than weekly intervals; leaves open optimal protocols for longitudinal venous research.
The venous system has been, to a large extent, underinvestigated in its role concerning cardiovascular disease. The success of systemic investigation of venous function hinges on the availability of valid techniques. An important characteristic of the validity of a measurement technique is its reliability. PURPOSE: The aim of this study was to test short-term and long-term reliability of venous outflow (VO) indices using the venous occlusion plethysmography technique. A secondary purpose was to compare venous measures to age, gender and various anthropometrical measures. METHODS: The study group consisted of apparently healthy males and females, aged 18 to 80 years. Venous indices were measured on two occasions (1 week apart), at rest and following 5 min of upper arm occlusion. Venous outflow measures were calculated fom the plethysmographic curve at the time .5 (VO.5), 2 (VO2) and the time interval between .5–2 seconds (VO.5–2). Venous capacitance (VC) was calculated by measuring the distance in mm from baseline to the maximum height of the inflow curve and dividing this distance by the height of the calibration mark. RESULTS: Intraclass correlation coefficient (ICC) revealed higher within-day reliability than one-week reliability for markers: ICC's = .931 vs. .622, .948 vs. .709, .965 vs. .518 and .971 vs. .431 for VC, VO.5, VO2 and VO.5–2, respectively. There was also good one-week reliability for these measures following occlusion (ICC's = .562, .701, .646 and .639) for all indices. Pearson correlation revealed associations between VO.5 and VO2 with arm length (R= −.344, p < .09; R= −.430, p < .03), respectively. Age was associated with VO.5–2 (R= −.340, p < .10). In addition, there were gender differences in VC (p < .009). Finally, a stepwise regression analysis was performed showing significant perdictive value of venous measures with arm length (F= 4.979, p < .03) and gender (F= 7.862, p < .01) CONCLUSION: Short-term VO measures showed stronger reliability than long-term measures. Additionally, it appears that vessel length and gender have an important influence on venous outflow.
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Ortego et al. (2002) studied this question.
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