Endothelial function can be assessed by measuring pulsatile changes in the fingers after occlusion of the upper arm using the Endo-PAT 2000 device, presented as Reactive Hyperaemia Index (RHI). A RHI value below 1.67 is suggested to indicate endothelial dysfunction. The aim of this study was to explore endothelial function, by measuring RHI, in young healthy subjects.Design and method:
Subjects aged 18 to 30 years, participating in the ongoing Malmö Offspring Study, were eligible for the study. A total of 186 subjects (105 females, mean age 24.4 years) were included in the analysis. The subjects were in a relaxed supine position, with their index or middle fingers placed in pneumo-electric tubes and the arms comfortably resting on arm supports keeping the fingers free from disturbances. Arterial pulsatile volume changes were recorded from the fingers on both arms before, during and after 5 minutes occlusion of the upper arm of the non-dominant arm. RHI was calculated as a post-occlusion to pre-occlusion ratio of the signal amplitudes.Results:
The mean RHI was 1.81 ± 0.55, with a range of 0.74 – 3.81 (Figure 1). In a univariate correlation analysis, RHI was inversely associated with waist circumference (Figure 2) and in females also with HDL cholesterol. Waist and height were associated with RHI in a linear regression model including age, sex, height, waist, LDL-C, HDL-C, triglycerides, smoking and physical activity.Results:
Figure 1. RHI in quartiles of age (range 18–30 years)Conclusions:
In all, 47% of young healthy subjects had RHI below the cut-off value of 1.67, a threshold generally used to define endothelial dysfunction. The reason for this is unknown but could be influenced by vasospasm phenomenon. Subjects with higher waist circumference showed lower values of RHI. A cut-off value for RHI of 1.67 for diagnosis of endothelial dysfunction is probably not applicable in young subject below the age of 30.