Evaluation of endothelial function using finger plethysmography

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.

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.

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.

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.