Evaluation of endothelial function using finger plethysmography

BACKGROUND: The aims of this study were to establish the optimum duration of blood flow occlusion to obtain maximal response and to compare the response after lower-arm and upper-arm occlusion. METHODS: Pulse wave amplitude was analysed using a novel finger plethysmograph (EndoPat; Itamar). For measuring reactive hyperaemic index (RHI) induced by forearm cuff occlusion, 30 healthy subjects were examined at different days in a random order of four cuff occlusion times (1.5, 3, 5 and 8 min). RHI induced by 5 min upper-arm cuff occlusion was also measured in 20 subjects. RESULTS: Average RHI was lower with 1.5 and 3 min forearm occlusion compared with 8 min forearm occlusion (P = 0.002 and P = 0.024). There was no significant difference between values of 5 min and 8 min forearm occlusion and between 5 min forearm and 5 min upper-arm occlusion (P = 0.1). All subjects reported less discomfort after forearm occlusion compared with upper-arm occlusion. CONCLUSION: Maximum response was reached after 5 min of blood flow occlusion and therefore this occlusion time is recommended. The response after forearm and upper-arm occlusion did not differ significantly. Forearm occlusion might be preferred as this caused less discomfort.